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Author Topic: Does anyone have a spare Lisa motherboard?  (Read 5454 times)

AlexTheCat123

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Re: Does anyone have a spare Lisa motherboard?
« Reply #45 on: December 03, 2019, 08:11:23 pm »

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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.
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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.
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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?
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rayarachelian

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Re: Does anyone have a spare Lisa motherboard?
« Reply #46 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.
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AlexTheCat123

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Re: Does anyone have a spare Lisa motherboard?
« Reply #47 on: December 04, 2019, 03:52:43 pm »

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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!
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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.
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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!
« Last Edit: December 04, 2019, 03:55:21 pm by AlexTheCat123 »
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AlexTheCat123

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Re: Does anyone have a spare Lisa motherboard?
« Reply #48 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?
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rayarachelian

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Re: Does anyone have a spare Lisa motherboard?
« Reply #49 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.
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rayarachelian

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Re: Does anyone have a spare Lisa motherboard?
« Reply #50 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) 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?"
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