Recent content by ijnfuso

On the old analog board I changed it, and this other analog board had already a changed one. So I either bought a bad optoisolator, an analog board with a new bad optoisolator or the logic board is laughing at me.. Edit; even with it changed the issue is still the exact same.

Well it's official, I have completely gone insane. I bought a CRT and nope, still same issue. I have no idea what this damn macintosh has.... I think I'm just going to give up and sell it as spare parts.

Seller on eBay proposed a good deal for a working CRT for the Mac... should I give it a shot..? Or should I try something else?

Here I am, a bit late (I got sick) but I bring news. I have reflowed every cold/cracked joint on the board and every connector joint, and double checked afterwards... to be honest, there weren't many but I still resoldered the connectors for good measure. Readings without the floppy attached...

Thanks for the tip... I'll do that tomorrow and update the thread after I reflow every bad joint (it's 1:30 am and I'm very tired)

I just checked the continuity, and both of the switches work as intended, nothing when the switch is not pressed. Well last time this thing worked the RAM wasn't a problem... I also tried reseating it and cleaning the connectors both on MB and RAM, and nothing changed. Haven't reflowed it... I...

I already tried lowering the voltage and it did not change anything. I also reseated the rom, the ram, tried putting in a battery, but I got no luck whatsoever.

Welp, the other day I got a new analog board. Recapped the three RIFAs, the seller said it was taken from a working mac, and guess what? It still has the same issue! I really have no idea.... could it be a CRT issue? Maybe the CRT has weird current draws or has issues, I don't know. Really stuck!

I checked online and found at This github page that Q12 can be a "BR103 reversed" (?) Now I don't know if that's possible or how to reverse a transistor, so, not really sure...

Searching online I read that Q12 doesn't have a direct replacement as it has been discontinued, and, can't find anything else... what can I do? Also It's almost like Q10 is glued to the metal bracket, how would I remove it?

Well, I was checking voltages between C35 and C39, I am getting around 300/301DC.... while I was doing that I heard a bang, and, it was Q12 that said goodbye (it exploded, popping the fuse too). And also seemed to burn R53 too....

Unfortunately, I have already tested every cable… the analog board is not even getting 12v or 5v to the power rail, and no high voltage as well…

Right- I am getting around 230V after the thermistor with switch on.... what else could I test

Well, I’ve replaced what is essentially everything on the AC part… And, it doesnt work. Same issue, no power to mainboard, no noises whatsoever, just complete death.

Thank you for the schematics. Really needed those!! I did indeed spend some time testing everything in the AC section. CR31 is indeed faulty, and also is CR30... with all these faulty components I'm starting to be amazed this thing even turned on a couple of times! I will also change the...