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I had the same problem. The voice coil of the speaker itself was broken. It should read around 60 ohms with a multimeter. After swapping the speaker sound worked fine. It’s a bit of a pain to swap because there are metal rivets holding it in place. I used needle nose pliers to smush them on the...

I'm happy to report this Mac is alive again! I found that pins 1,2,24 and 25, the Buffered Data lines of U14 (RAM chip closest to leaked capacitors) looked dead compared to the other three chips. The address lines all looked okay. I triple checked continuity which was fine. I had a salvage MLB...

They don’t appear plated at all. They just seem like raw steel. Will be interested to see if you find otherwise. 

BTW, if you have a 2-ROM board, you can use my notes in red  on the 4-ROM Bomarc schematic in the link above for your own testing.

OK I found one really dumb mistake on my part. The ROMs were in the wrong sockets. Verified they work okay in another board and put them in correctly on this board. That did change the symptom to vertical lines across the whole screen. I've checked every address line between the ROM/RAM/EAGLE...

Also powder coating is probably not a good idea for something like a SE frame. You’d have to retap the screw posts, the PCB might not fit in the slides and it would be electrically insulated. I guess you could overcome those issues with careful masking but it might not be worth it. 

I was able to find several on Yelp with searches  for “plating” and “electroplating”. I’ve used two different shops in the area and both were fine with small jobs. One had a minimum charge, but it was reasonable. 

I had some sets plated for use in MacEffects cases. I did some in nickel and others in zinc. They came out really great. I also recently restored a rusted out Lisa doing the same. The plating shop will remove the rust chemically and/or mechanically before plating. It won't fix any pitting, but...

This Classic II has vertical bars with no chime after a recap, rework and washing in an ultrasonic cleaner. The bars are present whether the ROMs are installed or not. The reset button does work. It'll just blip for a moment and display bars again. This board is the 2-ROM version. I've been...

Does that particular bit implicate a particular chip or address line?

This Classic had Sad Mac error 00000003 00040000. Caps were bad, but the board was in good shape. Replaced the caps all and ran the board through an ultrasonic cleaner. After, it still showed the same error. I replaced and cleaned underneath UH6, but no change. Installing the RAM expansion just...

Yes I completely rebuilt the motherboard. It has all new components and continuity checked everywhere. 

While waiting on the replacement ROMs, the following were checked: Both RAM cards Pin 39 to ... LS02 (U14A) pin 5,8,9 OK S138 (U12B) pin 3 OK RP1 pin 1 OK RP1 pin 16 to +5v OK CPU pin 105 (A19) to ... LS374 (West) pin 16 OK LS373 pin 16 OK LS374 (NE) pin 16 OK CPU pin 110 (A20) to ...

A friend shared the following:  So I'm going to check that next. Last night, as a troubleshooting step, I sprayed the socketed chips on the logic board with contact cleaner. I managed to install the HI ROM upside down and think I fried it. I've ordered a replacement. Such a rookie mistake!

Either card works in either slot. When both are installed there are no post errors but only 512k is recognized. 

Confirmed installed memory is 512k for either card installed in either slot when checking 2A8.    Thoughts on what to check next?

These both booted okay. GEMDOS got error 75 which is weird because no HDD is installed internal or external. I'll try the swapping @sunder suggested. I've already done that in the past and everything worked. But I'll do it again and check the amount of memory recognized in monitor.

There was no change to the symptom after fixing the caps and edge connector on the logic board.  Output of 2A8: 00 08 00 00  00 00 00 01  87 80 BF 00  00 00 00 00   So if 00080000 hex = 524288 or 512k, only one board is being recognized when both are installed.    Does this still...

Thanks for the suggestions. I'll give them a try. Earlier today I checked the caps on the logic board and found the one near the CPU had leaked. The others on the lower part of the board were fine. I went ahead and replaced all of them anyway. I'm also going through and patching some sketchy...

I have two 512k memory boards. Both pass the startup test in either slot on their own and they also work when installed together in either slot. The device can boot Mac Works or Lisa Office boot disks, but won't boot any diagnostic (either images via FloppyEmu or actual disks). The following...