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If I recall well there was a project about reverse engeneering a Mac Classic logic board. I saw a youtube video about it a while ago, regretably hadn't bookmarked it and can't find the video again. It was a completely black PCB that was breefly shown in a repair video of a Classic logic board...

I've got another troubled Classic logic board. This one is in rough shape due to capacitor leakage before I got it. The whole board was cleaned, caps replaced and several spots needed overcoating to protect the board. It has worked for several years since then. Now It's giving me nothing than...

This one is repaired. I had removed the Egret, cleaned everything up and put it back without result. Then I started with removing the Ram modules one by one and replace them with new chips. U14 was bad. After replacing that one the board worked again. There was no visible damage on the faulty...

I have checked all the pins of the Egret for continuity with the Bomarc schematics and they are all good. It can be the Egret chip itself of course but I don't have a spare one to test with. So it chimes at power on and when I press the interrupt immediately I get the death chimes which is...

My Classic II suddenly stopped working. I hadn't used it for about 2 months and now upon power on it chimes but gives me a screen with thin vertical lines. It are not the caps: both analog and logic board are recapped. It's a logic board issue. The board is very clean and upon examination under...

@nvdeynde Is it possible one of the jumpers on the logic board got moved/removed? I've never figured out what those jumpers do, but I know that if they're in the wrong configuration the machine doesn't work. The jumpers are in the right position as I have 2 of these boards, revision A...

Yes I know UF7 and UI7 control the Nubus interface. The board is in pristine condition, it's an Apple Service part in original box that I bought more than 20 years ago.. It was always my spare board, benchtested the board once a year, however now suddenly the nubus slots don't work anymore. It...

My IIFx does power on, chimes, and even boots from a floppy or it’s hard drive. However I have no video output since all Nubus slots are dead. I have checked the power pins of the nubus slots and all are ok. The Apple Graphics card is known good, same for m1212 monitor, psu, Rom, ram since...

I have a CC without sound on both the external speaker as the headphones socket. Logic and analog board is recapped, TDA7052A  is replaced to no avail. I don't have a 2nd machine to test with. I have checked for damaged traces from the headphones socket to the IC but couldn't find any.

Hi @OsvaL No I didn't find the cause of the problem. It's weird that nobody else replied  as I can't image I'm the only one with this problem.

I've recently acquired a Color Classic with a recapped logic board ( tantalum caps ) but capacitors C1 and C2 had the wrong value, 47uf instead of 100uf and C1 was mounted with the wrong polarity as well. The logic board has no sound, not from it's internal speaker but that can be due to a...

I've peeled off the film and removed the residue. Installing a new film is probably a winter project. I've got 2 of them and both have this issue. Another issue I have with the powerbooks 150 is that none of them want to cold start from it's internal battery. Pram is already replaced...

I got a Rasterops 8/24 xli from a friend for free. The card works in my Mac IIFx however there's no memory in the four 30-pin slots. I suppose they are not for additonal VRAM given 30-pin fast page memory is slow. Where are these extra ram slots used for and what memory sizes does the card take...

I have several Mac SE PSU's where the voltages are far out of specs. All of them are recapped. When measuring on the logic board FDD connector I get +4.75v and +12,75v with the voltage pot wide open in the PSU. When testing the bare PSU with the analog board disconnected, I get +4.35 Volts...

I have a weird issue with 4 of my Powerbooks 160 and 165: I can't set the time and date anymore. As soon as I leave the date/time Control panel, the date/time immediately jumps around randomly. It may jump ahead half an hour, jump ahead a week, jump behind by 50 years, you name it. Each time...

It can be a lot of things on both the logic or the analog board. It's hard to troubleshoot remotely. Do you see the bulb of crt  tube glow when it's powered on ? Otherwise if it i glows, it can be a video issue that it gets no signal from the logic board. Check the wire harness for...

Yes the problem is on the logic board. I missed the line where you wrote that you had swapped the board in another machine. It can be a faulty capacitor or resistor/diode out of specs...  Since it does boot spontaneously after a while I personally don't think it's a broken trace as then I...

Replace the optocoupler on the analog board. It's likely fading away as your +5 and +12v lines should be up in 1 second or less, not coming up slowly. If the initial voltage is too low to boot then you can get the garbled screen or other symptoms. If the voltage adjustment screw is already set...

All original would be 128kb ram without any modifications to the logic board but these boards are very hard to find in working condition and with the 400K FDD. Your logic board is upgraded from 128K to 512K and ram sockets were installed as is regrettably done with so many boards. That's also...

What happens if you press the reset switch a few times ? Is there a Pram battery on the logic board ? I know in 9/10 cases it's not necessary to have one installed for the Mac to start. However I have a Classic II board with a similar issue. Without Pram battery, I get a garbled screen and...