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And so the Lisa adventure begins
blusnowkitty:
Hey all, I just got a 2/5 today that needs a good bit of work, but nothing I don't think I can handle. I spent a good 3-4 hours today rewiring the I/O board to make it all work, and I found some further problems:
- I got two 1.2A power supplies and they both have issues - one will only power the system for a few seconds before they cut off, the other tries to power up but immediately dies. I'll be recapping both of these.
- Sony 400k drive is all gummed up, but that's no surprise. I've been degreasing and relubricating a bunch of these lately so easy fix.
- Base pin on Q11 on the I/O broke completely off. Unfortunately, whatever markings were on the package have long since faded away so I don't know what to replace it with. The other two transistors nearby are both 2N3904s, is that what I need to replace it with?
- When the PSU is cooperating long enough to actually power up the monitor, the image is as if someone rubbed Vaseline all over the screen. I'll be recapping the analog board as well, but while removing that board to get a list of capacitors this trimmer coil (L1 I think) apparently had been getting VERY hot over the years as it crumbled and broke as soon as I bumped it. I did manage to locate it back where it belongs and epoxied what remained of the plastic body back into place, but is this a concern?
Also, what's that on/off switch on the 2/5 I/O board for, anyway? Additionally, while the motherboard did sustain a little corrosion damage as far as I can tell only the exposed pins on the serial port connectors have been affected. The board slots are all in perfect shape.
stepleton:
Congrats on your new 2/5!
Do you know about the schematics available in the documentation section of http://lisa.sunder.net ? They're very handy! I found Q11 also listed as a 2N3904 here:
https://lisaem.sunder.net/LisaSchem/Lisa1SysIO2.gif
(it's at about N3 or N4 in bingo-card coordinates, over toward the right.) These schematics are not Apple originals and and may be revision dependent here and there, but they are also often easier to read than the true schematics here:
http://bitsavers.trailing-edge.com/pdf/apple/lisa/hardware/050-4008-H_IO.pdf
which also lists a 2N3904 on Page 2, straddling cells C1 and C2.
The switch you can find on Page 5 of the true schematics. It disconnects the battery from everything else on the I/O board, but it looks like the battery remains attached to the 5V standby rail on the motherboard and everything downstream from there...
I've never encountered that trimmer coil crumbling myself---maybe someone else has seen this?
blusnowkitty:
--- Quote from: stepleton on April 11, 2020, 09:42:33 am ---Congrats on your new 2/5!
Do you know about the schematics available in the documentation section of http://lisa.sunder.net ? They're very handy! I found Q11 also listed as a 2N3904 here:
--- End quote ---
Thanks for that, I'm sure it'll come in handy while I'm working on this I/O board. I've got capacitors ordered for the analog board and PSU so I'll get things recapped as soon as I get caps. Is there anything else I need to check out in the 1.2A PSU besides the caps?
So many patch wires...
https://twitter.com/blusnowkitty/status/1249012854809903105
rayarachelian:
Welcome!
--- Quote from: blusnowkitty on April 11, 2020, 02:07:30 pm ---Thanks for that, I'm sure it'll come in handy while I'm working on this I/O board. I've got capacitors ordered for the analog board and PSU so I'll get things recapped as soon as I get caps. Is there anything else I need to check out in the 1.2A PSU besides the caps?
So many patch wires...
https://twitter.com/blusnowkitty/status/1249012854809903105
--- End quote ---
The most likely dead caps are going to be the large rectangular semi-see through yellow ones - if you see those, that PSU has never been recapped and must be. Next are the large cylindrical ones. Careful when ordering some of those caps are special - non-polarized and can deal with AC currents. Be sure you've ordered similar caps.
Sometimes the large zener diodes on the PS go bad. Those should be easy to check.
Check the back side of the PS, reflow the solder - the heat can sometimes cause the solder joints to crack.
I'd also remove the memory boards and disconnect the lite adapter (before you do, use a marker to note which end of the cable plugs in) and try to power on the Lisa. This will tell if you if there are shorts.
You can also jam a bit of paper into the front power cut off switch on the bottom left front behind the bezel and thus test with the cover off, and similarly jam a piece of paper into the back of the power supply cut off switch to test with the back off, but I suspect you already know this.
blusnowkitty:
--- Quote from: rayarachelian on April 11, 2020, 03:33:20 pm ---Welcome!
The most likely dead caps are going to be the large rectangular semi-see through yellow ones - if you see those, that PSU has never been recapped and must be. Next are the large cylindrical ones. Careful when ordering some of those caps are special - non-polarized and can deal with AC currents. Be sure you've ordered similar caps.
Sometimes the large zener diodes on the PS go bad. Those should be easy to check.
Check the back side of the PS, reflow the solder - the heat can sometimes cause the solder joints to crack.
I'd also remove the memory boards and disconnect the lite adapter (before you do, use a marker to note which end of the cable plugs in) and try to power on the Lisa. This will tell if you if there are shorts.
You can also jam a bit of paper into the front power cut off switch on the bottom left front behind the bezel and thus test with the cover off, and similarly jam a piece of paper into the back of the power supply cut off switch to test with the back off, but I suspect you already know this.
--- End quote ---
I'm well aware of how bad the Rifa caps are. I was working on a project with both my Mac 128 and 512ke plugged up and all the Rifas in both of those decided to blow at the same time, it was not fun... So yeah, I'm pulling the Rifas as soon as I get capacitors in. Right now I'm just focusing on the electrolytics and the Rifas but I'll replace other caps and parts if need be, thanks.
I've also noticed that with the power supplies as they are now, using the semi-working one I can usually only get one or two power-up attempts out of them - one lasts just long enough to bring up the POST screen and shows errors, the other only lasts a second or two before it shuts off. The completely dead power supply I can usually get it to click a bit and power off instantly. In both cases it usually takes several hours for whatever's inside to allow me another power-on attempt. Very strange... But, can't do any real testing 'til I get everything recapped.
On another note, Ray, I blame you for getting me into Lisas in the first place. I was watching LisaEm's progress for a year or two prior to the very first working build of the emulator :D
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