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  1. Arisotura

    Macintosh IIfx motherboard revision A vs B differences.

    According to a quick check in the schematics: * J20 connects the CPU's /CDIS pin to ground, that pin is otherwise pulled high. * J103 connects /CIOUT (wherever that comes from) to pin 64 of the memory controller, that pin is otherwise pulled to ground. * J106 connects pin 11 of UK6 to ground...
  2. Arisotura

    Fix0ring a Macintosh IIfx

    Thinking about it, another possibility would be to try and enlarge the hole to expose the traces that connected the minus-terminal via to the ground plane, and solder to that. However that might be problematic, depending on the order of the layers inside the board (if there is a power plane...
  3. Arisotura

    Macintosh IIfx motherboard revision A vs B differences.

    Only real difference I can see are that revision A has some jumpers that are missing in revision B. Rev B also doesn't have the list of names at the top. The chips under the RAM slots are slightly different (yellow instead of black on rev B), but I saw some pics of rev B motherboards with black...
  4. Arisotura

    Fix0ring a Macintosh IIfx

    According to the schematics, the minus terminal for BT2 connects to ground. I'll find a good ground on the back on the board and run a bodge wire :)
  5. Arisotura

    Fix0ring a Macintosh IIfx

    Second battery holder was gone already when I got it, and I planned for that in my parts orders. As a side note, the minus via for that one is completely and entirely gone, so I will have to get creative to reconnect that. C24 was present, it was a tantalum but it was already half detached, so...
  6. Arisotura

    Macintosh LC recapping woes

    I actually learned from this video that this is by design -- the analog ground goes through the RF shield, which eventually connects to the power supply's ground. Obviously this only works if the motherboard is seated in its case... I removed the ground bodge I had done, and, sure enough, audio...
  7. Arisotura

    Fix0ring a Macintosh IIfx

    I was looking around on eBay when I saw this one, so I thought, hey, why not give it a try. It was provided as 'not working' and having undergone battery leakage, but it did not look that bad... Some of these components aren't looking too hot, but compared to the pics of Maxell-bombed Macs...
  8. Arisotura

    Recapping a quite leaky LC475 - Video is red

    You got three lines going out to the display port for red, green and blue signals. An always-red picture would suggest that only the red signal is making it to the monitor. Now why that would happen, might be some corroded traces on the board, might just be a dirty display port... Judging from...
  9. Arisotura

    LC TDK power supply starts when it feels like it

    Well, finally got the proper 2SK1024, and put the power supply back together. It seems to work really nicely now. So I guess in the end all is good... we'll see how this goes.
  10. Arisotura

    LC TDK power supply starts when it feels like it

    Lil' update on this. I replaced the few resistors I'd blown, still waiting for a replacement MOSFET (original one went bad too). I took a 2SK2611 MOSFET from another power supply, which is electrically compatible. The power supply now seems to work reliably, however the 2SK2611 is bigger than...
  11. Arisotura

    LC TDK power supply starts when it feels like it

    Well, I did a few hunts for leftover cap gunk. Basically a visual inspection, but also heating up solder joints -- any bubbling through the liquid solder is a telltale sign of cap gunk. I thought I had thoroughly cleaned the damn thing, guess I wasn't thorough enough, because I did find quite...
  12. Arisotura

    LC TDK power supply starts when it feels like it

    Well, I spoke too soon. The damn thing is being flaky again. I replaced the microcontroller and the optoisolator, to no avail. I could try going for the shunt regulator but I doubt that is the issue - when the PSU is in non-working state, there is no current at all in the output side. However...
  13. Arisotura

    Macintosh LC recapping woes

    I redid my soldering with proper cleanup and flux and all. Did the difference, now it's working reliably. I did check the traces around capacitors, there was one broken trace, which may or may not have been there before, but it was quickly taken care of. I also had to add a couple bodge wires...
  14. Arisotura

    LC TDK power supply starts when it feels like it

    Lil' status update on this, after some more rework, it's finally working reliably. I have gotten some replacement parts if it ever shits itself again, tho.
  15. Arisotura

    LC TDK power supply starts when it feels like it

    I ordered some supplies so I can redo my soldering on my Mac LC motherboard the right way. In the meantime I figured I'd focus on the power supply, which is the typical TDK one. Of course, it had crapoed capacitors, so I replaced all the output-side capacitors and cleaned up the mess. The power...
  16. Arisotura

    Macintosh LC recapping woes

    Well, I redid every single capacitor I had installed, turns out some of them weren't quite right. Anyway now it's all redone and good. But, still, no change.
  17. Arisotura

    Macintosh LC recapping woes

    So a while ago I got a Macintosh LC, power supply was dead but in the meantime I was able to get it working by connecting it to an ATX power supply. It had no sound but otherwise seemed to work fine. Obviously the capacitors were at fault there, so I got new capacitors and set to work... ...
  18. Arisotura

    Macintosh LC recapping woes

    EDIT- my bad, this is the wrong forum
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