KLund1 Posted February 27, 2018 Share Posted February 27, 2018 OK here is the situation so far.Apple /// 1, well call it 1 for less typing. 1 was in very bad shape. Lots of mouse pee, dropping, dust, and cobwebs all over the MB. The PUS looked good.I did a very careful job of cleaning it up. I washed the MB. let it dry for many days, after blowing out water with my air compressor. I reseated every IC, inspecting each for bad pins. Some had a bit of corrosion. I scraped those pins and reseated a couple times to loosen anything in the sockets. I air blow it all off careful again. I let it dry for another day just in case. Hooked it up to it's PSU, and nothing. Not even a blink on the screen. The red LED near the rear of the MB did not light. I tested the PSU with my multimeter, not under load, and got 5v on some line. I do not know which should have a voltage, as this 1's psu cable is all black wires.Ok now for Apple /// 2. It was just very dusty. I dusted it off, hit it with the air compressor. I also hit the psu with some air. reconnected it all up and booted. I lives. I got a beep at first power. I get a memory test, then a screen full of '5v+'with several varying shades of green squares between them. This repeats until I press Reset. Then the floppy drive (FD) spins, there is a hiss from the speaker. and 'RETRY' shows on the screen. I have not cleaned the case, keyboard, or the FD of 2 yet.I then connected 1's Mb to 2's psu,keyboard, and FD, and I get a beep, and brief flicker on the screen. I press reset, and the speaker has a his, but no FD spin, or anything on the screen.From this I assume 1's psu is actually bad in some way. And that 1's MB is partly alive. I have cleaned the case, keyboard, and floppy of 1I watch a youtube video of a A3 booting and after a reset press, 'Apple III' shows on screen. But I can't tell if a disk was inserted or not.Other notes:These are my first A3's. Both are A3 Plus, 256k, 5v memory board systems. I have several NOS Apple Utility disks. I can use a multimeter, and am fairly confidant in my soldering skills. No scope, no EE knowledge. I know the difference between a resistor, and a capacitor, but do not understand fully the marking on either. I know just enough electronics repair to be my own worst enemy.I think I should put 2's Mb, and PSU in 1's case, with it's clean but untested keyboard, and untested FD. Y/N?How to fix 1's MB? Would swapping 1's IC's, one at a time with 2's IC's work, with a boot of each after each swap? I have 2 working A3 screens, but only known working psu.Suggestions on how to proceed.Thanks !! Quote Link to comment Share on other sites More sharing options...
eightbit Posted February 27, 2018 Share Posted February 27, 2018 OK here is the situation so far. Apple /// 1, well call it 1 for less typing. 1 was in very bad shape. Lots of mouse pee, dropping, dust, and cobwebs all over the MB. The PUS looked good. Eewwwww... Quote Link to comment Share on other sites More sharing options...
GlowingGhoul Posted February 27, 2018 Share Posted February 27, 2018 Eewwwww... Well, the pee corrodes traces, so the pus looks good by comparison! 1 Quote Link to comment Share on other sites More sharing options...
KLund1 Posted February 28, 2018 Author Share Posted February 28, 2018 The traces look ok under a magnifying glass, but I can on the the surface traces. No easy way to see if there was damage inside the board. I am going to assume it is not, and proceed. But what is the next step? Quote Link to comment Share on other sites More sharing options...
KLund1 Posted February 28, 2018 Author Share Posted February 28, 2018 Ok I tested 1's psu under load connected to the 1's sick MB. I get 2v on the 5v line and 4V on the 12v line. So it is obviously is bad.How to proceed? There is no visible damage to any of the caps. Not even a crack on the expansion seams on the tops. The bottom looks new.So where to start? Replace the largest caps first? Quote Link to comment Share on other sites More sharing options...
Keatah Posted February 28, 2018 Share Posted February 28, 2018 (edited) Complete board removal and wash, with chips removed. Salt crystals migrate with humidity cycles. Then slight coating of the ICs with Deoxit. 1 drop on a q-tip per 5 or 10 chips. Then 2 or 3 removal/insertions of each chip to swipe the fine layer of oxidation away. I see you did that, minus the contact cleaner.. Edited February 28, 2018 by Keatah Quote Link to comment Share on other sites More sharing options...
KLund1 Posted March 1, 2018 Author Share Posted March 1, 2018 I think I'll Deoxit all the IC's, and insert a few times each and see it the may help. Gives me something to do with watching TV... Not holding out much hope but worth a try. Quote Link to comment Share on other sites More sharing options...
Keatah Posted March 1, 2018 Share Posted March 1, 2018 It will have to work, otherwise the next steps are randomly replacing "important looking" chips, or getting out the scopes and meters. Quote Link to comment Share on other sites More sharing options...
Caterpiggle Posted March 3, 2018 Share Posted March 3, 2018 Hello KLund1 , Do you have happening to own Apple RGB Color Monitor 100 ? Quote Link to comment Share on other sites More sharing options...
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