Mac IIx Mainboard Repair

gonzo · Mar 25, 2016

Hello,

I recently tried to recover an old IIx. When I jump started it the first time, no sound came up at all, not even the dead one. So I swapped all the SMD electrolyte capacitors and cleaned the Mainboard with alcohol. Now it brings the broken sound after jump starting, nothing else. The ROM module is in place, tried with four or all eight RAMs which were installed, same result, just the broken boing. And no video output.

Where can I continue to debug now? What are other typical broken parts in those machines.

Thanks in advance and best regards,

Florian

360alaska · Mar 25, 2016

If your willing to send a highres picture of your logic board many in the forum enjoy looking for bad traces and such. Does your video card have electrolytic caps on it?

unity · Mar 25, 2016

My guess is bad traces also. I have a IIx board that looks nice, until one looks close. I have it as a future project but expect it will never boot. Its a pretty common issue on the IIX, something to do with where the boards were made.

gonzo · Mar 25, 2016

360alaska said:
If your willing to send a highres picture of your logic board many in the forum enjoy looking for bad traces and such. Does your video card have electrolytic caps on it?

I'll do some hires pics later.

The Video Card (Apple Computer Macintosh II Video Card) has only non-SMD caps which look OK.

Elfen · Mar 25, 2016

Try booting it without the video card.

And which video card is it? I have all 3 that Apple made for the Mac II Series and they all have SMD/SMT caps on them

gonzo · Mar 25, 2016

Hi folks,

without video card it is the same, just the dead boing. I tried the video card in all NuBUS slots, no difference.

Thanks.

gonzo · Mar 25, 2016

Hi,

the pictures of the mainboard and the graphics card can be found here: https://www.hidrive.strato.com/share/x7sd5uwnbe

Thanks in advance.

Florian

unity · Mar 25, 2016

It would appear you did a decent soldering job. The pics are not high enough resolution to pick out tiny details, but nothing stands out. Caps appear in place, etc.

I would check power supply voltages.

Also, what an odd board with that battery board. The IIx is designed for proper battery holder right on the board OR direct wire style. Mine had normal mounts, like on a IIfx, etc. Weird for me to see that.

360alaska · Mar 25, 2016

Yeah, we need higher res.

gonzo · Mar 25, 2016

You can download the pics in original resolution when you click on the small cloud beyound the picture (in the center of the screen), just doublechecked you can even read the partnumbers on the chips and caps.

This cloud solution from my webhoster is not that optimal, I know.

If you already tried this, I can take better pictures tomorrow.

I already checked the power supply, its OK, ripple is < 0.1V

Thank and good night,

Florian

unity · Mar 25, 2016

That is what I did. But the pics have a soft focus and are still not high resolution enough. You probably need to take at least 4 close-up pics, divide the board up basically into areas for pics.

360alaska · Mar 25, 2016

The traces near C4 look questionable, can you check them?

Unknown_K · Mar 25, 2016

The battery board upgrade was common, mine have them.

What size RAM modules are those? Stick with a known good set of 1MB/each and 8 chip non parity will work.

Macdrone · Mar 26, 2016

Im watching this with much attention as my IIx will jump start on, and shut down (normal) but start normal does not work. I have read a bunch but the hand drawn schematics dont match what the board looks like and Im not getting the real idea how to check traces or I would just run new wires point to point, one at a time till I found the correct fault.

techknight · Mar 27, 2016

there hasnt been a IIx board that I havent been able to fix.

Most if not all of them turn out to be corroded/eaten traces near the IC behind the nubus slots.

And there is 2 or 3 traces that run all the way across the board between that IC, and the switch that go bad too.

Macdrone · Mar 28, 2016

Then it sounds like you should PM me your address and give me a quote because I wont figure it out lol. Seriously.

gonzo · Mar 28, 2016

Hi folks,

just uploaded a brunch of pictures as requested: https://www.hidrive.strato.com/share/x7sd5uwnbe

Thanks in advance,

Florian

gonzo · Mar 28, 2016

Hi folks,

just uploaded a brunch of pictures as requested: https://www.hidrive.strato.com/share/x7sd5uwnbe

Thanks in advance,

Florian

360alaska · Mar 28, 2016

This looks like trouble:

Mac IIx Mainboard Repair

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