LisaList2

General Category => LisaList2 => Topic started by: AlexTheCat123 on November 02, 2019, 06:17:35 pm

Title: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 02, 2019, 06:17:35 pm
Hello! I just got my first Lisa in the mail (a Lisa 2/5) and it has the usual battery corrosion problem that plaques so many of these machines. I am now trying to clean up the corrosion and I think that I will be able to repair all of the boards except for the motherboard, which is probably beyond repair. Does anyone have a spare motherboard that I can purchase to get my Lisa working?

Thanks!
Alex
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on November 03, 2019, 08:27:06 am
How bad is your current board? What's damaged on it?

There is one on ebay that's listed for parts, but it looks like the CPU and I/O board connectors are messed up. If your connectors and parts are good, you could try that one.  The two memory edge connectors are identical to each, and the CPU and I/O board connectors are also identical to each other (just offset horizontally). So you may be able to use an I/O edge connector for a CPU board connector in another board and vice versa.

The ZIF connectors on the expansion slots are the hardest things to find replacements for, so be careful to save those.

You could also buy a new one from here: http://vintagemicros.com/catalog/brand-apple-lisa-motherboard-lisa-lisa-p-299.html but this looks like a bare board without connectors, chips, or other parts,, so as long as you've got the time to move all the components over, you should be fine.

If by some chance you run across a 2/10 motherboard, you could use the parts from it, but don't use the actual board in a 2/5 as you'll lose the parallel connector (unless you rewrite the chassis with a 2/10 set of data and power cables.)
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 03, 2019, 09:02:53 am
Unfortunately, the connectors for the CPU and I/O boards are damaged, so the board off of eBay will not work. Luckily, the ZIF connectors are fine. All of the ports on the back of the board are rusted as well. I could probably find replacements for these parts, but I do not have the necessary desoldering equipment to get the old ones out of the board. There are just so many pins to desolder and I would probably end up damaging the board with excessive heat. I am tempted to just fire it up in its current condition (after I clean off the corrosion) and see what happens, but I am sort of nervous about doing this. Do you think that this is a good idea or am I likely to further damage it?
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on November 03, 2019, 11:43:09 am
If you give it a good cleaning, and then reflow the solder on the corroded connections with lots of flux before you turn it on, it might be good enough.
Be sure to blow out any cruft from under the chips that are soldered on as well. Heating up corroded pins on chips and reflowing the solder will help too.

If you're creative and handy you might be able to fix the clips on those broken CPU and I/O board connectors on that board. You'd need to figure out what shape they are by extracting one of the old ones, and cutting a new one, then carefully inserting the new one in. Just be careful to not allow it to get loose and short out a pin next to it.


If the corrosion made it all the way inside the traces inside the board, you'd have to to use a VOM set to continuity testing and beep out the connections, should a connection not work, you'd have to add a jumper wire and glue it to the board. But then, over time, it'll just keep eating traces and it will fail again.

You wouldn't need super specialized equipment to desolder, just a desoldering sucker with a soldering iron. There are cheap ones that have both the pump and a soldering iron together like this for under $10: https://www.amazon.com/Velleman-VTDESOL3U-Vacuum-Desoldering-Heater/dp/B00B88FRME/
You'd still be doing it single pin at a time. The only danger is from overheating a pin and lifting a pad, or damaging the pin on the connector, if you're not careful enough.

Give it a shot, if it's already dead, you don't have much to lose.

John used to have the fully populated motherboards over at Vintage Micros, maybe reach out to him and see if he has any left if you don't have the time to invest and just want it to work.

Edit: When my MBP17" died with a GPU failure, I bought one of these for ~$40: https://www.amazon.com/Kohree-Rework-Station-Solder-Digital/dp/B00JVM3WBC/ - it's basically a hot air gun whose temperature you can precisely control. You could use this along with a lot of liquid flux to either reflow solder on the back of the board, or even to help desolder the board. Be careful with it to avoid melting the board or components. I'd look up the temperature of leaded solder, such as is used in the Lisa first and set it to that.

In my case I used this to reflow the GPU in my old 17" macbook pro as I said, so if you've got some old Macs that might have that same issue, it might be worth investing in. Would work on other things where the BGA connectors can fail, like Sony Playstations. I've used this thing 3x already, so it more than paid for itself by getting another 2 years out of an otherwise dead machine.

I'd be careful to not overheat the solder joints if you're just reflowing them with this thing, otherwise, they'd melt and fall through the other side. So you'd want a quick pass once or twice, just enough to make the solder go liquid but not more than that.

I'd practice on some old electronics junk first like old PC boards or radios or whatever that are broken and you don't care about.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 04, 2019, 06:22:28 pm
I have decided to give it a shot, but I may need some help with the component values on the motherboard. A few of the parts are so corroded that I can't read them at all. Can someone tell me the part numbers of Q1, Q2, C12, and the resistor packs that connect to the ports on the back? I ordered some desoldering wick and I will try removing a few of the damaged parts over the next few days.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on November 05, 2019, 10:14:28 am
Take a look here: http://bitsavers.org/pdf/apple/lisa/hardware/lisa-motherboard-enhanced.pdf
It's a bit difficult to read since it's grayscale and hasn't been cleaned up, but zoom in and it is legible.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 05, 2019, 07:16:40 pm
I just desoldered the connector for the I/O board and I found that some of the pads underneath the connector have been corroded away. I also lifted a few pads on the bottom of the board when I was desoldering it. How should I go about repairing this damage or is the board just toast?
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on November 05, 2019, 08:42:12 pm
I just desoldered the connector for the I/O board and I found that some of the pads underneath the connector have been corroded away. I also lifted a few pads on the bottom of the board when I was desoldering it. How should I go about repairing this damage or is the board just toast?

So at this point I'd say, take a deep breath and say "It's a good day to die" like a Klingon, and then accept that this board is dead.
Now that doesn't mean you throw it out, it means you're free to do whatever you need to do to get it working again and, if you can't, you don't worry about being disappointed. However, whether you do get it to work or not, you'll have learned some really neat skills.

It's probably toast for the fully corroded pads as the corrosion will travel through the trace over time. The lifted pads might go back on if you go very gently, and they can be repaired.

You can try reflowing the solder on the corroded pads if enough material is left, then measure connectivity to the other end. If you get near zero ohms, you're fine.  This is a long shot, but a conductive metal paint pen might help, likely it won't.  like this: https://www.amazon.com/Bare-Conductive-Electric-Paint-10ml/dp/B00KBXT6JW/  More likely, if you can follow the trace to the other end, solder a copper wire to it and route it back to the lifted pad then solder the other end of the wire directly to the connector's pin or whatever attaches to the pad you should be good. Be sure to glue that wire down to the board so it won't move.

There are techniques for repairing lifted pads which might help: https://www.instructables.com/id/Repairing-a-Damaged-Pad-on-a-PCB/ - this following video is for SMD so it's going to be a lot easier on the Lisa.  https://www.youtube.com/watch?v=YQdqX0DxBXM - google around some more, you might find better stuff than this.

Assuming you don't give up and make it to the end, once you're done and it works again, you should seal the board with some laquer - possibly krylon spray could work, or nail polish, not sure if you can get proper conformal varnish like this: https://www.amazon.com/MG-Chemicals-422B-340G-Silicone-Conformal/dp/B008O9YGQI/

I do have a similar lisa to fix, like yours, but instead, only on both a CPU and an I/O board: https://lisalist2.com/index.php/topic,18.0.html so yeah I feel your pain.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 06, 2019, 01:27:56 pm
I just looked more closely at the motherboard schematic and it looks like most of the pads that are corroded away connect to the serial ports and the few that do not should be easily repairable. Would it damage anything if I fixed everything but the serial ports and just used the Lisa without them?
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on November 07, 2019, 06:19:17 am
I just looked more closely at the motherboard schematic and it looks like most of the pads that are corroded away connect to the serial ports and the few that do not should be easily repairable. Would it damage anything if I fixed everything but the serial ports and just used the Lisa without them?

Unless you want to use LisaTerm or BLU or Zterm, you should be fine without the serial ports.
That said, BLU is a really useful tool, off the top of my head, I think BLU wants serial port B with hardware handshaking, so if you can fix port B, you'll be in good shape.

You'll want to at least fix the signal ground, RX, and TX lines, though you'll likely need the handshaking lines too.

see: https://www.lammertbies.nl/comm/cable/RS-232.html especially the section that shows a table labeled "DB9 - DB25 conversion" cable with hardware handshaking. The pins on the DB25 side are the ones you care about on port B.

Now, if you have a classic 68k Mac that has a GCR capable floppy drive, even if it's a super drive, you should be able to make Lisa floppies, though one with an 800k floppy drive is preferred due to the head width. And in that case you might not need to use BLU. (Don't bother with USB floppy drives, they're just MFM PC drives only - I think there might have been one that supports GCR, but they're as probably as rare as Lisa 1s.)

You'd transfer disk images to that Mac, and then make the disks on that Mac and insert them into the Lisa.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 07, 2019, 08:28:04 am
I have some old Macs with 800K drives, so making floppies should not be a problem. I will try to get the Lisa working first and then I might try to fix the serial ports if I can get it powering on.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: Lisa2 on November 07, 2019, 12:14:33 pm
Now, if you have a classic 68k Mac that has a GCR capable floppy drive, even if it's a super drive, you should be able to make Lisa floppies, though one with an 800k floppy drive is preferred due to the head width.

Ray, I think you are remembering an issue with PC 5.25" HD drives writing DD formats.

To clarify (not to hijack this thread), the number of tracks (and head width) is the same for the Macintosh DD (800K) and HD (Super) Drives.   Some later mac FDCs had issues writing Lisa disk images in a way that the Lisa's FDC prefered, but the drive itself was never the issue.

Rick
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 09, 2019, 04:28:24 pm
I have cleaned up the corrosion, replaced several corroded parts on the motherboard, and have tested every single connection on the board (which took a very long time) and there is an improvement! The light on the power switch illuminates when I press it and will stay on for a short period of time (maybe about one second), but then turns off again. Is this a common problem and does it narrow down any potential faults with the computer?
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on November 09, 2019, 05:10:07 pm
Quote
I have cleaned up the corrosion, replaced several corroded parts on the motherboard, and have tested every single connection on the board (which took a very long time) and there is an improvement! The light on the power switch illuminates when I press it and will stay on for a short period of time (maybe about one second), but then turns off again. Is this a common problem and does it narrow down any potential faults with the computer?
Yes! That's a great sign!
Most likely your next issue is either 1. the I/O board traces around the COP421, or 2. the power supply is weak and needs new capacitors. 2 (power supply capacitors) is even more strongly indicated if you hear some ticking, though the light on the switch would only stay on while the button is pushed, if it stays on after you let go of this switch, it might not be this, but I'd check the large capacitors in the power supply either way, if you see cracks in the large rectangular yellow ones (if they're yellow and somewhat transparent, they're the original ones, and are likely long dead), and the large cylindrical electrolytics.

I've also seen this caused by the floppy cable inserted backwards in the LisaLite card.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 12, 2019, 07:53:33 pm
I think I'm making progress! I have patched every bad trace that I can find on the I/O board and now the power light will turn on and stay on when I hit the switch. A transistor (Q3 or Q4 I think) let out some magic smoke when I turned it on for the first time, but it seems to be part of the audio amplifier, so I don't think it is necessary, at least for now. If I press the power switch again after turning the computer on, it will turn back off, but only if I let it run for about 20 seconds before trying to power off. There is still nothing on the display, though. I don't even hear the high-pitched whine that CRTs make when they are on, so I suspect that there is something wrong with the circuitry that drives it. Does the CRT turn on when you press the power switch or does it require a signal from a board in the card cage before it energizes? If it requires some sort of signal before it turns on, then I probably have a problem with the CPU or I/O board, but if it turns on with the rest of the computer, then I may have to mess with the video board to make it functional.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on November 13, 2019, 11:00:44 am
I think I'm making progress! I have patched every bad trace that I can find on the I/O board and now the power light will turn on and stay on when I hit the switch.

Woohoo! Congrats!

If I press the power switch again after turning the computer on, it will turn back off, but only if I let it run for about 20 seconds before trying to power off. There is still nothing on the display, though. I don't even hear the high-pitched whine that CRTs make when they are on, so I suspect that there is something wrong with the circuitry that drives it. Does the CRT turn on when you press the power switch or does it require a signal from a board in the card cage before it energizes? If it requires some sort of signal before it turns on, then I probably have a problem with the CPU or I/O board, but if it turns on with the rest of the computer, then I may have to mess with the video board to make it functional.

You might still have power supply issues, wetware RAM may be unreliable, but from what I remember the +/-33V lines are what power the CRT.
If you take the top off and turn the lights off you should see the back of the tube glow a bit where the cables go in. Don't do this just yet, read the rest of this.

I'm assuming you've already played with the brightness and vhold controls in the back of the Lisa?

So the contrast is controlled by a latch on the I/O board attached to one of the VIAs, but if the CPU board is dead or it has no RAM, it won't tell the VIA to set the contrast to a visible setting. So if there's a problem anywhere in that chain, you'll also get a black screen, but it could be lots of other issues from not being able to access RAM, or a dead CPU board or anything else like dirt on the contacts of the motherboard or broken traces between the CPU board, motherboard, or the connector or cable going to the analog board.
So next we'll want to try get some video output, any output, even if it's just turning up the brightness all the way and getting a white glow from the CRT. If you can't get the CRT to light up at all, or glow in the back, could point to the power supply.

If you're getting just one dot on the CRT and nothing more, it could mean that the flyback transformer is dead, or could be the VSROM or associated circuitry on the CPU board.

see: https://lisafaq.sunder.net/single.html#lisafaq-hw-vid_jumpy (https://lisafaq.sunder.net/single.html#lisafaq-hw-vid_jumpy) and especially read the whole video section and pay attention to the safety warnings. I'd suggest wearing insulating gloves when you do that and keeping one hand behind your back. CRTs are very dangerous and they can kill you. If you know all this already, and you seem to, then great, I don't mean to be telling you basic stuff, but I don't want some kid, a few years from now, who never saw a CRT in their life before, reading this forum and then sticking their hand in around a CRT and getting themselves killed.  ;)

Now, the next step would be to either purchase a flat plastic screw driver kit - I mean the blade is made of plastic or other non-conductive material, not just the handle of a screwdriver. You could also use a really small spudger with a flat end, or to cut a plastic knife into the blade of a flat screwdriver.

If you don't feel like cutting a plastic knife yourself, you could buy something like these which are ceramic bladed, but it's a waste of money. ( https://www.amazon.com/REAMTOP-Slotted-Ceramic-Alignment-Screwdriver/dp/B06XGF8Q8Q/ (https://www.amazon.com/REAMTOP-Slotted-Ceramic-Alignment-Screwdriver/dp/B06XGF8Q8Q/) )

The reason you need this tool is that the next step will deal with you opening the top case and poking around the analog video board and should the screwdriver fall in, you don't want it to a) break the CRT or b) short something out, or worse c) electrocute you, so a plastic disposable knife is the best tool for this job, but you'll need to cut the blade into the right size to fit into the trimpots that you can use to adjust the video board controls using diagonal cutters.

Now, after you remove the front face of the Lisa, remove the card cage, and go underneath the top of the Lisa at the top, you'll find some screws. Undo those and you'll be able to remove top of the Lisa's case. You can see this (in reverse) here: https://youtu.be/ZXL2Ku23nSc?t=360 and a better one here: https://youtu.be/0r-zLeYygzc?t=1293 (at those time codes).

You'll need to insert something into the power cut off switch at the bottom left of the Lisa's face, like some rolled up PostIt note or whatever, and also into the hole at the back of the power supply where you see the back door has a bit of plastic sticking up. This will allow you to turn the Lisa on without these covers, which is dangerous and why those power cut off switches are there.

Reinsert the card cage after you've done this and now the Lisa should be topless, and backless  :-[ :o and yes, ofc, faceless.
Power it on. Wear gloves and with one hand behind your back, use a magic marker to mark the original position of all the trimpots - you'll move them very slowly and gently while the Lisa is on and one at a time. The trim pots may have some wax on them to keep them in the factory position, but you'll be breaking that seal if it's still there.

Next use the plastic screwdriver to gently and slowly move the trim a little bit at a time pots back and forth to try to adjust the video. If you've got any sign of video - even if it's just a white glowing screen, great, if not, you've got more debugging to do. If one trim pot doesn't produce results, bring it back to the original position that you used the marker to note it.

Since you don't have a working speaker you don't know if it's beeping, or if there's a RAM issue or whatever. It might be worth fixing the two transistors just to hear any warning beeps. Beeping would be a good sign that the CPU and the boot ROM are good even if the RAM might not be or something else is wrong. Perhaps you could trace the sound output pin off the VIA - should be the output of the shift register, maybe CB1 or CB2 or CA1 or CA2, sorry too lazy to look it up right now, and then attach a logic probe between that pin and ground to that and listen to the beeps, if any, that way.You can find what the warning beeps mean here: https://lisafaq.sunder.net/single.html#lisafaq-hw-rom_beeps
I could suggest trying to get an external monitor attached to the video out RCA jack, but likely that will be near impossible even if the video is fully working since that output is so weird - I've tried and haven't gotten very far with normal SD video stuff.

So what this tells you so far is that the COP421 is working and powering on and off (most of) the system. What you don't know right now is, 1. is RAM good? 2. is the CPU board fully good? 3. Is the CPU ROM good? 4. is the rest of the I/O board good (though that shouldn't affect video except for the contrast latch and DtoA.)

If either the CPU board is bad or the RAM isn't accessible, or the contrast latch on the I/O board is bad (or not set by the CPU) you'll also get a black screen and some beeping.

If you have a logic analyzer or even a logic probe you can poke around and see if there's some signals going in and out of the CPU. If you have a fox and hound cable tracing system (like this one: https://www.amazon.com/Meterk-Multifunction-Instrument-Maintenance-Continuity/dp/B071K8L32H/ (https://www.amazon.com/Meterk-Multifunction-Instrument-Maintenance-Continuity/dp/B071K8L32H/) )  you can use just the "hound" part which is really just an AM radio to pick up signals from the various boards and you should hear some noise as you move near each component. You won't be able to hear the really high frequency signals from the 68k, but you'll hear enough noise from other parts without even touching any pins to give you a rough idea to know if something is working.

It would really help if you had access to another Lisa so you can swap parts and see what's working or not, but if you're not near anyone with a Lisa, no worries, just keep poking at it.

You've made some really great progress, don't stop now, keep going, you're getting closer. These kinds of debugging things are like an onion where you're peeling off layer after layer of problems, but you don't really know how many layers deep there are to go.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 13, 2019, 01:31:49 pm
Thanks for the suggestions! I will try messing with the trimpots on the video board and probing the audio signal on CB2 of the VIA with an oscilloscope when I get home from school today.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on November 15, 2019, 07:57:27 am
So how did it go, any further symptom elimination?
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 15, 2019, 02:23:05 pm
Unfortunately, no. The computer won't power on at all anymore and I am trying to figure out why. I did not really have much time to troubleshoot it yesterday or the day before, but I am going to try and fix it this afternoon. Maybe something is wrong with the power supply? I hope the COP421 isn't dead because I have no idea where to find a reasonably-priced replacement.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 16, 2019, 08:22:18 am
I just it powering on again. The trace that caries the PWRSW signal on the I/O board failed and I had to patch it. I tried adjusting the CRT controls on the video board and there was no change, so then I tried probing the audio on the VIA with an oscilloscope. Whenever I turn the computer on or press the reset button on the back, I get a 300-ish hertz signal for about 120ms, then 80ms of inactivity, and another 120ms 300 hertz signal. Then the line remains inactive until I reset the machine. Since the Lisa is supposed to click twice when you turn it on and I got two pulses, it seems like it might actually be somewhat alive. I also tried putting a disk in the floppy drive to see if it would try to read it and I can hear the heads move once or twice and then it goes silent. This makes me think that it is actually trying to read the disk. Do you agree that this probably means that the computer itself is working?
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: patrick on November 16, 2019, 10:47:16 am
Beeep-Beeep means memory failure. So now you'll have to check the traces between CPU and memory board.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on November 16, 2019, 05:18:03 pm
Well, the 68000 is good, so likely most of the CPU board is good, though we don't know if the MMU is good, or the RAM. As Dr. Patrick said, looks like it couldn't read the RAM ( https://lisafaq.sunder.net/single.html#lisafaq-hw-rom_beeps ), so as he said, check the connections to RAM boards, or the pins from the CPU board that go to RAM, maybe swap the RAM boards around as well.

You could try inserting just one memory board in one slot, then turn the Lisa off and move it to the other slot to see if anything changes.

I'm pretty sure it's not trying to boot at this point. The BIOS takes a very long time to test RAM and other hardware before it tries to boot, and even then it usually puts up a menu asking where to boot from (unless the PRAM has a setting that says boot from ProFile/Widget and that hard drive is on and accessible.)

On power on the MMU is in Special I/O space with the boot ROM mapped at address zero and also high memory. It will then do a checksum of the ROM, and beep if it's wrong. Once it finds some RAM, it will go out of SIO space and into MMU context zero, the display will turn on and it will start testing RAM and video memory will be at high RAM.

If there's a fault in page zero RAM where the exception vectors are stored, I think it will fail to show any video and will beep low. In your case you're getting lo,lo tones, so it can't see any RAM.

In terms of the floppy activity, it's more likely that the 6504 CPU which controls the IWM and floppy drive noticed there's a floppy there and initialized the drive which may have spun the motor or moved the heads a bit. But it's certainly not trying to boot yet.

I do see an X/Cops replacement board on vintagemicros for about $100, if it turns out bad, but so far we know it's good enough to power on the Lisa and have the main CPU start and fail the self test. So as long as all the pins and the connection to the mux chip it has are still good, it's likely working. You won't know until you have video if the keyboard and mouse are working. (And if the keyboard isn't working, most likely the foam caps are dead not the COPS on the I/O board.) Most likely any issue around COPS421 functionality is more likely caused by bad traces than by that chip itself going bad. Reflowing solder on its pins will help stop the corrosion too.

I'd replace all the large capacitors in the power supply, even if they're working, chances are they're over 20 years old, more like 35 if they're the originals so many would have failed, or are about to. This won't necessarily fix the CRT issue, but its still worth doing as you're going to have to do it at some point anyway.
However, if the 33V power supply output isn't working due to some caps not working, fixing the power supply will help you get video. This won't happen until it can access RAM, but I think it will still provide power to the CRT and the tube will warm up and glow, and pushing the brightness high should produce a white screen with some horizontal retrace reflection stripes, and since you haven't said you saw those, likely the PS has some issues.

I do see this as well incase you need it: https://www.ebay.com/itm/AMP-60-120-Card-Edge-Connector-Fits-Apple-Lisa-Motherboard/141821714914 - this connector should fit both the I/O and CPU boards.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 17, 2019, 06:30:31 am
I am only using one RAM board at the moment because the edge connector on the second one seems to have some corrosion damage, but I will try to fix the connector on the second board and try it out to see if anything changes. I have already checked the traces between the RAM and CPU boards, so I don't think that I have any problems there. As for the CRT, the power supply is putting out the 33V signal as it is supposed to, but the CRT is doing absolutely nothing. Not only is there no video, but there is not even a glow at the back of the CRT and these is no high-pitched whine from the flyback transformer. I also looked at the schematics for the power supply and determined that the video board is supposed to be sending 300V and -100V into the supply, which are supposed to run to the brightness and focus potentiometers on the back, but there is no voltage on either of these lines. This makes me think that something is wrong with the video board itself.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on November 17, 2019, 02:51:35 pm
I am only using one RAM board at the moment because the edge connector on the second one seems to have some corrosion damage, but I will try to fix the connector on the second board and try it out to see if anything changes. I have already checked the traces between the RAM and CPU boards, so I don't think that I have any problems there. As for the CRT, the power supply is putting out the 33V signal as it is supposed to, but the CRT is doing absolutely nothing. Not only is there no video, but there is not even a glow at the back of the CRT and these is no high-pitched whine from the flyback transformer. I also looked at the schematics for the power supply and determined that the video board is supposed to be sending 300V and -100V into the supply, which are supposed to run to the brightness and focus potentiometers on the back, but there is no voltage on either of these lines. This makes me think that something is wrong with the video board itself.

Ok, incase you don't have it, here's the video board schematic: https://lisaem.sunder.net/cgi-bin/bookview2.cgi?zoom=0?page=24?book=6?Go=Go

One thing that's common is that heat can cause the solder joints on these boards to crack. (or perhaps the corrosion has spread there too) I'd pull it out (careful of capacitors, CRT, etc.) and reflow the solder there, maybe replace some caps.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 17, 2019, 06:28:16 pm
Thanks for the schematic! I just removed the video board (which was quite difficult because some of those connectors were really tight) and there do appear to be about 20 questionable looking solder joints on it. I will reflow the whole board and see what happens.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: patrick on November 17, 2019, 06:34:01 pm
There is an auxiliary video output on the back of the machine. That will not work with any known monitor type due to its weird line frequency, but you can check with an oscilloscope whether video is generated at all.

Next step, check both sync signals sent to the video board. Without HSync the flyback circuit is not running, therefore the screen remains dark. Nevertheless you should see the heater glow, it is getting 12V directly from the PSU.

Check all supply voltages for ripple. Replace capacitors if the ac component is too high, but leave them alone when ripple is still in spec. Electrolytic capacitors from the '80s sometimes fail, but most of them are still in excellent condition today. Parts from the '90s are much worse (leaking etc), and today's stuff lasts exactly until your warranty has expired.

Best idea: find someone living close to you who is able to check your I/O, CPU and RAM boards with his/her machine. Then you can be sure that all issues are located on the mainboard or video section.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 17, 2019, 07:42:23 pm
I reflowed the entire video board and I get something on the display now! The first time I turned it on after the reflow, the screen was bright and it displayed an error code of 49. The second time, there was no error code. The third time, however, the screen started out bright and suddenly dimmed to the point that I can barely read it, even with the lights off. I played with all of the potentiometers, but I can't get it any brighter. What happened?
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on November 18, 2019, 01:00:38 pm
I reflowed the entire video board and I get something on the display now! The first time I turned it on after the reflow, the screen was bright and it displayed an error code of 49. The second time, there was no error code. The third time, however, the screen started out bright and suddenly dimmed to the point that I can barely read it, even with the lights off. I played with all of the potentiometers, but I can't get it any brighter. What happened?

So 49 is not a good thing, it indicates A or F line trap, this shouldn't ever happen with just a plain boot ROM - might happen if it tried to boot off a hard drive with bad code on it, but not from the ROM, so there might be issues somewhere else on the CPU board, or the ROM is bad. You did say you have a scope, right, you might want to hook it up between the normal +5V and GND rails on the CPU and see if the 5V line is clean or if it drops out or is noisy - this would indicate power issues - though there should be a filtering cap near the CPU to prevent that. You shouldn't be randomly seeing A or F line errors like that. Something is up with the CPU board still. I'd guess maybe it's a contact that's still marginal from the motherboard corrosion and unlikely to be power, but who knows.

It's also possible that something on the analog video board just burned out, but keep power cycling it after waiting a few hours to allow the caps to drain and see if it comes back or not. If it comes back, it's likely a marginal capacitor. It could be as simple as one of the trimpots, or the brightness control in the back not making good contact, they do go bad over time or wear out.  Could also be that one of the fixed cracked solder joint cracked again or a trace is somewhat broken and moving the board fixed it, but heat expansion from being on caused it to separate again. Could also be a transistor that's being used as a brightness amplifier gave out?
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: Lisa2 on November 18, 2019, 05:34:59 pm
I reflowed the entire video board and I get something on the display now! The first time I turned it on after the reflow, the screen was bright and it displayed an error code of 49. The second time, there was no error code. The third time, however, the screen started out bright and suddenly dimmed to the point that I can barely read it, even with the lights off. I played with all of the potentiometers, but I can't get it any brighter. What happened?

A common failure point for the Video board, is the 7824 voltage regulator at U1.  Usually when it goes it cooks the 120 Ohm resistor R1 near the R2 (width) pot.  Look closely at R1 and see if it's is discolored ( you can see R1 without removing the board ).  If U1 is bad there will be no power to the flyback transformer..

Rick


Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 18, 2019, 08:29:15 pm
Success! I found a few solder joints on the video board that I forgot to reflow and I also found a few more traces that I forgot to patch on the CPU board. I now have a bright and stable picture and the Lisa shows the TESTING... screen and puts checkmarks over all of the components. However, I feel like it completes the test a bit too fast. It gets through the entire test in about 10 seconds, which seems a bit too fast, even though I only have 512K of RAM installed for it to test. It does not show the ROM version in the corner of the screen like I think it is supposed to. After this, it goes to the Startup From... menu and I can use the mouse to select an option. However, it displays two floppy drives in the menu, even though I only have one. If I select the second drive, it attempts to boot from disk and then promptly ejects the disk since there is nothing on it. The weird part is that it shows a picture of a Twiggy disk with an X over it along with the Error 23 (disk not readable) instead of a 3.5" disk.  Given these strange occurrences, do you guys think that I have the wrong ROMs installed? They do have a handwritten marking on them that looks like a C, which makes me think that these are revision C ROMs that only work with Twiggy drives.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: Lisa2 on November 19, 2019, 12:18:40 pm
It does not show the ROM version in the corner of the screen like I think it is supposed to.
The display of ROM version was added around Rev. D.  It may be possible this is an early "twiggy" ROM that does not display the revision.  Does your IO ROM have a sticker on it? 

Rick
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 19, 2019, 01:17:30 pm
The I/O ROM is from Sun Remarketing to allow the Lisa to work with the 800K drive that is installed. Why would the Lisa have the Sun I/O ROM combined with Lisa 1 CPU ROMs? This just seems a bit weird. I am guessing that I will have to replace the CPU ROMs in order to get it working properly, right? Also, can I run LOS with the Sun Remarketing I/O ROM or will I have to swap it out too?
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on November 19, 2019, 04:23:18 pm
Off the top of my head, D should be compatible with both Lisa 1 and Lisa 2, so it should be fine. The 800K ROMs should work with Lisa Office System as well.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 19, 2019, 04:26:21 pm
I think that I have revision C, not revision D. From what I have read, revision C is only compatible with the Lisa 1. That would explain why it shows two drives under the Startup From menu instead of one.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on November 20, 2019, 10:47:28 am
I think that I have revision C, not revision D. From what I have read, revision C is only compatible with the Lisa 1. That would explain why it shows two drives under the Startup From menu instead of one.
That's pretty rare if it is an original C ROM, well that is, rare in the sense of an original ROM from Apple back from 1982 and has the original sticker on it. All the ROMs are available on bitsavers and if you have a an EEPROM programmer, you can burn your own, if not I'd contact John at Vintage Micros for a set.

Fair enough, though, I'd still worry about fixing the rest of the hardware first before worrying too much about the ROM version. Any luck with the video board and other related stuff?
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 20, 2019, 02:28:18 pm
The video board is working great and I just fixed the second memory board, so it seems to recognize the full 1MB now. Also, a transistor is on the way to get the sound working. It seems that I may have been wrong about the ROM version because the computer boots just fine from a MacWorks 1.0 boot disk, which makes me think that it has to be revision D or later, even though it has a C written on it. Although the MacWorks disk worked just fine, it gives an error 49 whenever I try to boot from a LisaTest 3.0 disk, so there may still be some problems with it. Unfortunately, the floppy drive in the Quadra 700 that I was using to make disks for the Lisa last night stopped working in the middle of making a disk, so I have not been able to test any other disks on it yet. I will set up another Mac this afternoon and make some more disks to see if it will boot from any of them.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on November 21, 2019, 12:02:22 pm
The video board is working great and I just fixed the second memory board, so it seems to recognize the full 1MB now. Also, a transistor is on the way to get the sound working.

That's awesome! Congrats! You've just about got yourself a working Lisa! Well done!


It seems that I may have been wrong about the ROM version because the computer boots just fine from a MacWorks 1.0 boot disk, which makes me think that it has to be revision D or later, even though it has a C written on it.

When you first power on the Lisa, during the self test, but before the boot menu that shows floppy, you'll see the version in the upper right corner, i.e. D/A8 for the "D" boot ROM version and A8 for the I/O ROM.

Although the MacWorks disk worked just fine, it gives an error 49 whenever I try to boot from a LisaTest 3.0 disk, so there may still be some problems with it.
 

Yeah, I'd just assume a bad floppy at this point, download another from elsewhere and - there are many versions of LisaTest, so not sure which one is valid for what system exactly, but sounds like that one is throwing an A or F-Line exception during boot, so it's likely corrupt.

Unfortunately, the floppy drive in the Quadra 700 that I was using to make disks for the Lisa last night stopped working in the middle of making a disk, so I have not been able to test any other disks on it yet. I will set up another Mac this afternoon and make some more disks to see if it will boot from any of them.

I'd say try to fix the serial ports next, so you can fire up BLU.

Another possibility is to get a FloppyEmu ( https://www.bigmessowires.com/floppy-emu/ ) and get the A/B switch board for it so you can switch between the physical floppy drive and the emu, these are awesome. You can use a tiny screen to select a disk image from an SDHC card, and not have to deal with actual floppies at all. I have one, as well as an X/Profile, both are highly recommended.
BTW, the X/Profile does work with certain CF to SD card adapters so don't worry about CF cards getting scarce.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 21, 2019, 04:52:43 pm
Quote
That's awesome! Congrats! You've just about got yourself a working Lisa! Well done!
Yep! It's just about fully working at this point. I just need to fix the serial ports and test the parallel port to make sure that it is working properly. I am thinking about building an IDEFile instead of buying the X/ProFile because it is a whole lot cheaper. I just got a transistor in the mail today to replace the one that popped on the I/O board, but there was still no sound when I turned it on and the transistor got very hot, so I killed the power. Maybe the op-amp is bad?
Quote
When you first power on the Lisa, during the self test, but before the boot menu that shows floppy, you'll see the version in the upper right corner, i.e. D/A8 for the "D" boot ROM version and A8 for the I/O ROM.
My Lisa doesn't show a ROM version in the corner for some reason.
Quote
Yeah, I'd just assume a bad floppy at this point, download another from elsewhere and - there are many versions of LisaTest, so not sure which one is valid for what system exactly, but sounds like that one is throwing an A or F-Line exception during boot, so it's likely corrupt.
You were definitely correct about this! I made another floppy disk for LisaTest and LOS and they both booted just fine. The machine even passed all of the tests in LisaTest!
Quote
I'd say try to fix the serial ports next, so you can fire up BLU.
Those serial ports are going to be tough to fix, but I'll give it a try. I tried fixing them earlier and I discovered that one of the chips on the I/O board that controls them had its pads completely corroded away! I managed to get the chip out, but it is going to be difficult to patch all of those connections in addition to the other connections that I need to fix for the serial ports.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on November 22, 2019, 08:06:12 am
Yep! It's just about fully working at this point. I just need to fix the serial ports and test the parallel port to make sure that it is working properly. I am thinking about building an IDEFile instead of buying the X/ProFile because it is a whole lot cheaper.

There's also this: https://github.com/stepleton/cameo/tree/master/aphid (https://github.com/stepleton/cameo/tree/master/aphid) - see which one suits your needs.

I just got a transistor in the mail today to replace the one that popped on the I/O board, but there was still no sound when I turned it on and the transistor got very hot, so I killed the power. Maybe the op-amp is bad?

Could be. Whatever feeds either the base or the collector into that transistor is likely pushing too much power, or maybe there's a short somewhere.

My Lisa doesn't show a ROM version in the corner for some reason.

That's odd, are the right and top edges of the display visible? Could they be outside the screen? If not it could be this version is very old and doesn't display the version, or the version is displayed while the CRT is still warming up and not yet visible. If it's the latter, pressing the reset switch after it shows the boot display will let you see it.

Another thing you could do is go into service mode and look around memory to see the version bytes. To get into Service Mode, boot off the floppy drive without a disk in, and when it throws an error press Apple-Shift-S.  The I/O ROM version is stored at 02A1. You can read the boot ROM version at the end of the ROM itself around the fe3ff0 area after the copyright string.

For the H ROM, there is source available which says this, but the address may vary for earlier ones.
It doesn't seem to write the boot ROM version to low memory. If it turns out you have a rare ROM, I'd dump it out and see if it matches the ones on bitsavers, if you don't find a match, it would be important to send it to bitsavers.

Code: [Select]
3FF4|                       ;************ COPYRIGHT NOTICE ***************************************
3FF4| 43 38 34 41 50 50 4C  HDGMSG  .ASCII  'C84APPLE'      ;                               CHG005
3FFB| 45
3FFC|                       ;*********************************************************************
3FFC|
3FFC| 02                    VRSN    .BYTE   $02             ;version 2                      CHG001
3FFD| 48                    REV     .ASCII  'H'             ; rev H                         CHG001
3FFE|                               .ENDC
3FFE|
3FFE|
3FFE| 0000                  LAST    .WORD   $0000           ;checksum word for ROM test
4000|                               .END

Those serial ports are going to be tough to fix, but I'll give it a try. I tried fixing them earlier and I discovered that one of the chips on the I/O board that controls them had its pads completely corroded away! I managed to get the chip out, but it is going to be difficult to patch all of those connections in addition to the other connections that I need to fix for the serial ports.

Yup, that's the Zilog 8530 SCC. It does have a lot of pins, so you'd have quite a lot of traces to follow and patch.  :(
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on November 22, 2019, 01:40:31 pm
Quote
There's also this: https://github.com/stepleton/cameo/tree/master/aphid - see which one suits your needs.
Wow! I didn't even know about this! Thanks for the info!
Quote
That's odd, are the right and top edges of the display visible? Could they be outside the screen? If not it could be this version is very old and doesn't display the version, or the version is displayed while the CRT is still warming up and not yet visible. If it's the latter, pressing the reset switch after it shows the boot display will let you see it.
The entire screen is definitely visible and I have tried pressing the reset button so that I can see the entire boot sequence, but it never displays the version. I have ordered the revision H ROMs off of eBay just for the sake of having the latest ROM version.
Quote
If it turns out you have a rare ROM, I'd dump it out and see if it matches the ones on bitsavers, if you don't find a match, it would be important to send it to bitsavers.
This is a great idea, but unfortunately I don't have an EPROM reader.

Unfortunately, I am going out of town tomorrow and I won't get back until Thanksgiving day, so I won't be able to do any more work on the Lisa until then.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: Lisa2 on November 22, 2019, 02:33:35 pm
If you get your serial ports working you can use BLU to dump the roms.

http://sigmasevensystems.com/BLU.html

Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on November 22, 2019, 02:59:53 pm
Wow! I didn't even know about this! Thanks for the info!

You're welcome. Tom does log on here occasionally so you can ping him about it. He's awesome. He had one of the earliest websites about the Lisa on the internet. You can find it here off archive.org, though some images might be missing here and there. https://web.archive.org/web/20021225192819/http://tangerinecs.com/~amber/lisa/saq.html (https://web.archive.org/web/20021225192819/http://tangerinecs.com/~amber/lisa/saq.html) :)

Quote
The entire screen is definitely visible and I have tried pressing the reset button so that I can see the entire boot sequence, but it never displays the version. I have ordered the revision H ROMs off of eBay just for the sake of having the latest ROM version.
It may well be the "D" ROM, I do have one on a CPU board somewhere, but who knows maybe I forgot whether it shows the version or not.

Quote
This is a great idea, but unfortunately I don't have an EPROM reader.
You don't need one. You can dump it from MacWorks if you've got a language to write some code in like a C compiler, you can directly access 0x00fe000-0x00fe3fff. I did that early on using ZBasic 5, but that was over the serial port. Shouldn't be too hard to have it written to a file instead.
Might even possible to do that from MACSBUG, though not sure how you'd tell MACSBUG to write something to disk, or maybe TMON.

see:
Quote
Unfortunately, I am going out of town tomorrow and I won't get back until Thanksgiving day, so I won't be able to do any more work on the Lisa until then.
Happy Thanksgiving, and I'm glad you've got an almost fully working Lisa now.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: D.Finni on November 24, 2019, 05:35:10 pm
You don't need one. You can dump it from MacWorks if you've got a language to write some code in like a C compiler, you can directly access 0x00fe000-0x00fe3fff. I did that early on using ZBasic 5, but that was over the serial port. Shouldn't be too hard to have it written to a file instead.
Might even possible to do that from MACSBUG, though not sure how you'd tell MACSBUG to write something to disk, or maybe TMON.
Newer versions of MacsBug, in the 6.x series, can dump to disk, but I don't think these newer versions will run under MacWorks.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on December 03, 2019, 06:20:16 pm
Sorry for the delay in posting. I finally got the chance to install the revision H ROMs that I ordered and now the sound has started working, but the Lisa plays a low-pitched beep (which I believe means CPU or memory error) when it turns on and displays random garbage on the screen. I tried reverting back to the original ROMs and the sound still works, but the same thing happens. I have tried moving the memory boards around and reseating all 4 boards several times, but nothing is fixing the problem. This happened last time I took the boards out as well and I was able to fix it by reseating things several dozen times, but it's not working this time. My guess is that the edge connectors on the boards are intermittent due to me having to repair them with copper tape that begins to deform after lots of insertions and removals. Do you guys have any ideas about a better way to repair these edge connectors on the cards that have been destroyed by the corrosion or would I be better off buying one of these https://www.ebay.com/itm/143185668902 (https://www.ebay.com/itm/143185668902) with a pristine edge connector and swapping my CPU and ROMs over to it? I am pretty sure that the CPU board is the problem, not the RAM, because the connectors on the RAM boards were not impacted by the corrosion.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on December 03, 2019, 07:48:47 pm
Sorry for the delay in posting. I finally got the chance to install the revision H ROMs that I ordered and now the sound has started working, but the Lisa plays a low-pitched beep (which I believe means CPU or memory error) when it turns on and displays random garbage on the screen. I tried reverting back to the original ROMs and the sound still works, but the same thing happens. I have tried moving the memory boards around and reseating all 4 boards several times, but nothing is fixing the problem. This happened last time I took the boards out as well and I was able to fix it by reseating things several dozen times, but it's not working this time. My guess is that the edge connectors on the boards are intermittent due to me having to repair them with copper tape that begins to deform after lots of insertions and removals. Do you guys have any ideas about a better way to repair these edge connectors on the cards that have been destroyed by the corrosion or would I be better off buying one of these https://www.ebay.com/itm/143185668902 (https://www.ebay.com/itm/143185668902) with a pristine edge connector and swapping my CPU and ROMs over to it? I am pretty sure that the CPU board is the problem, not the RAM, because the connectors on the RAM boards were not impacted by the corrosion.

IMHO, those connectors off ebay are cheap enough that it would be worth buying a few just to have as spares even if you manage to repair the ones there.
They're around $15 each, right, but a new fully populated board would be around $250-$500, so it's worth having them around.

I suppose this is going to suck, but since you have a scope, I'd inject a high freq signal (maybe 10-20MHz?) into one end of a scope using a signal generator in series with the scope, then the other two leads I'd put one on the top side of the connector and one on the same connector's pin at the bottom of the motherboard. If the waveform shows up messed up on that pin likely needs a little help.  i.e. something like:

Code: [Select]
   to-lisa-mobo-pin-bottom<---signal-generator-ground, signal-generator-out-->oscilloscope lead a, oscilloscope-lead-gnd----->to-lisa-mobo-pin-top.

Before doing that which will likely take about an hour or two, have you tried spraying contact cleaner on the whole connector and then using an antistatic electronics brush (they look like toothbrushes, but black) to clean the whole connector?  i.e. brushes like these https://www.amazon.com/Plastic-Portable-Brushes-Cleaning-Keyboard/dp/B074LZ649V/ or (careful with these, you don't want to breathe the dust in and may be overly aggressive to clean metal) https://www.amazon.com/SE-7616SB-Fiberglass-Scratch-Brush/dp/B003NHDITW/ and https://www.amazon.com/MG-Chemicals-Electrosolve-Residue-Electronics/dp/B005DNR0N4/

Would you be able to try removing the copper tape and flowing some solder on top of the contact instead? not much but enough to tin the pin a bit, and maybe hopefully to get rid of corrosion?

It could also be that it's not the connector but the trace underneath is getting eaten by the corrosion.

It could also be something else like one of the MMU registers or connectivity to it has gone bad, and it's not the connector, but since you say you saw the copper tape deforming, than that's likely the root cause.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on December 03, 2019, 08:11:23 pm
Quote
IMHO, those connectors off ebay are cheap enough that it would be worth buying a few just to have as spares even if you manage to repair the ones there.
They're around $15 each, right, but a new fully populated board would be around $250-$500, so it's worth having them around.
I already bought some of those connectors off of eBay and replaced the connectors for the CPU and I/O boards on the motherboard. The part that I had to use the copper tape on was the male end of the connector that is built into the cards that plug into the motherboard.
Quote
Before doing that which will likely take about an hour or two, have you tried spraying contact cleaner on the whole connector and then using an antistatic electronics brush (they look like toothbrushes, but black) to clean the whole connector?  i.e. brushes like these https://www.amazon.com/Plastic-Portable-Brushes-Cleaning-Keyboard/dp/B074LZ649V/ or (careful with these, you don't want to breathe the dust in and may be overly aggressive to clean metal) https://www.amazon.com/SE-7616SB-Fiberglass-Scratch-Brush/dp/B003NHDITW/ and https://www.amazon.com/MG-Chemicals-Electrosolve-Residue-Electronics/dp/B005DNR0N4/

Would you be able to try removing the copper tape and flowing some solder on top of the contact instead? not much but enough to tin the pin a bit, and maybe hopefully to get rid of corrosion?
The pads on the male end of the connector are so corroded away that there is literally no copper left on the board. Thus, I have to use the copper tape or something similar to make new pads and cannot simply put some solder on them or clean them with a brush.
Quote
I suppose this is going to suck, but since you have a scope, I'd inject a high freq signal (maybe 10-20MHz?) into one end of a scope using a signal generator in series with the scope, then the other two leads I'd put one on the top side of the connector and one on the same connector's pin at the bottom of the motherboard. If the waveform shows up messed up on that pin likely needs a little help.
This is a great idea, but I am concerned that even if I find a fault, the copper tape that I use to repair it will start coming off again and I will probably end up with the same issue that I had before after a few insertions and removals. I either need to get a new CPU board like the one that I mentioned in the previous post that has good edge connectors or I need to find a better way to fix the pads on the existing connector. Any ideas about how to do this given that the pads are completely gone?
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on December 04, 2019, 02:59:19 pm
The pads on the male end of the connector are so corroded away that there is literally no copper left on the board. Thus, I have to use the copper tape or something similar to make new pads and cannot simply put some solder on them or clean them with a brush.

Ouch! I didn't realize it was the PCB itself that got corrupted, and thought you'd meant the motherboard PCB and the pin on the connector.
So you'd need to somehow rebuild that part of the PCB. Copper is going to be too soft. I'm not sure how those fingers are made, I do recall the HWG mentioning they're gold plated though via ENIG.

These might help, but I've never done this, so all you're seeing is the results of searching, if it works out, pls let us know what you did incase others have the same issue. From the looks of it, you'll have to re-electroplate it with both nickle and gold as in the 1st video to make a permanent fix as long as the pads are still there. But it's pricey. The link he has quotes $350 for the kit.
If it gets too terrible, you might consider these: https://www.ebay.com/itm/Apple-Lisa-CPU-Boards-All-Missing-Some-Components-Non-Working-Need-Repair/143185668902 <- these are dead CPU boards, likely CPU + ROMs + VSROM has been harvested, you could try these and try to debug them, but they did have something wrong with them.
Another choice is: https://www.ebay.com/itm/Apple-Lisa-CPU-Motherboard-Card-Version-Version-3A-820-4009-B-620-0119-N-KL/123210714205 which is ~$180 with shipping, but it is a 3A CPU board, so you'd swap the VSROM and ROMs after you get it. It's still cheaper than the $350 electroplating kit.
Keeping my fingers crossed for you, let us know what you decided to do and how it went.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on December 04, 2019, 03:52:43 pm
Quote
Ouch! I didn't realize it was the PCB itself that got corrupted, and thought you'd meant the motherboard PCB and the pin on the connector.
Sorry for not making that clear!
Quote
https://www.youtube.com/watch?v=RdLDlAl2iWo <- I'm guessing this is what you did, but the guy doesn't say how to make it permanent.
This is exactly what I did, just multiplied by about 40 since I had so many connections to fix.
Quote
From the looks of it, you'll have to re-electroplate it with both nickle and gold as in the 1st video to make a permanent fix as long as the pads are still there. But it's pricey. The link he has quotes $350 for the kit.
Wow! That's expensive and definitely a bit out of my price range! I am going to just buy one of the $20 dead CPU boards off of eBay and see if I can get it working again. Are you sure that they have other faults or are they just missing a CPU and the ROMs?

I have ordered parts to build the Cameo/Aphid ProFile emulator that you suggested a few posts ago and I am hoping that I can actually get the Lisa working again so that I can test it!
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: AlexTheCat123 on December 05, 2019, 05:59:39 am
Now it's magically started working again! I just let it sit for about a day without touching it at all and now it turns on again! I wonder why this happened?
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on December 06, 2019, 02:09:55 pm
This is exactly what I did, just multiplied by about 40 since I had so many connections to fix.

Sigh... the pain we must endure for our hobby!

Wow! That's expensive and definitely a bit out of my price range! I am going to just buy one of the $20 dead CPU boards off of eBay and see if I can get it working again. Are you sure that they have other faults or are they just missing a CPU and the ROMs?

So not sure if this is an option, but under teh $350 price tag he does sell extra gold and nickel dust and the leads separately, I think the gold is $100 don't recall the other prices, but maybe if you buy the refill items and attach it to your own $10 radio shack power supply or whatever, it will be good enough to use it? Still the dead CPU boards are much cheaper.

I wonder if there's some way to cut a few fingers off an edge connector, perhaps from another board and epoxy glue it onto the rotten ones on your CPU board, then use jumper wires to fix the connection?
I have no idea how to go about doing that, but if it's possible to lift the pads with aggressive high temperature desoldering, it might work on edge connector fingers too? Maybe if you have old PC ISA card that has no resale or personal value, that you don't care about? like an old modem or some other junk card?
Maybe use a very fine tip drill bit and drill in the middle of the card (vertically into the PCB itself) to get some of the fiberglass split, and once split use a file to remove the fiberglass material from the bottom of the finger? Or maybe a very fine blade handsaw?

No idea what's broken with the CPU boards, you can ask John and see what he says. Maybe he remembers what other issues those boards had. I think he harvested the CPU and ROMs off them because they were faulty and sold those separately, so for sure those CPU boards are going to be broken. Not sure how much effort you'll need to put in to debug/fix them, but at least you'll have spare parts from your other CPU board that you can transplant.

I have ordered parts to build the Cameo/Aphid ProFile emulator that you suggested a few posts ago and I am hoping that I can actually get the Lisa working again so that I can test it!

Awesome! Let Tom know once you've got it built.
Title: Re: Does anyone have a spare Lisa motherboard?
Post by: rayarachelian on December 07, 2019, 01:24:56 pm
Since it seems to be working again, I'm just going to leave it alone for now. If it breaks again (which it probably will), I'll probably look into buying one of those cheap CPU boards.

Sounds like it's some intermittent issue, so this points either to a capacitor which would drain over the time, or a temperature related issue where a trace is partially disconnecting or shorting.

When I got this Lisa, it didn't have a keyboard and Lisa keyboards seem to be incredibly expensive, so I decided to build a keyboard emulator. I'm not sure if you have heard of it, but it's called LisaKeys (https://github.com/RebeccaRGB/lisakeys (https://github.com/RebeccaRGB/lisakeys)) and it uses an Arduino to emulate the keyboard. Is seems to work great when typing manually, but I tried using the included Python program that types disk images into memory in the Lisa's service mode, it does not recognize the Arduino for some reason. It says that it did not receive a response from the board, even though it's connected and powered on. Has anyone else here had this issue and do you know any fixes for it?

I've not tried to build this thing, but Rebecca is a member here, perhaps you can PM her or better yet, open a new thread with the topic of "RebeccaRGB's LisaKeys Adapter?"