Hmm, that's weird.
I don't know much about this, but I think I've read in passing (while attempting to solve other problems) that symptoms like this can be indicative of either failed resistors or diodes somewhere in the affected circuit.
I guess you could check for burnt R's and D's and replace any that you find? It could be as simple as a broken solder joint too, so check any connections for continuity while your at it.
Isn't that why we all use these archaic machines?
This is a painfully slow method of moving files, about 3 minutes a Mb. I guess it would still be faster than writing a Mb to a floppy and then loading the floppy into another machine. It's slow enough that the SE/30 is able to be used for light games while the transfer is happening, though it hanged when I tried to pay a second game of Spades.
I have a few options for sneaker net, but for moving a file or two, this will likely work good enough until I find the SCSI to ethernet bridge. I don't know for certain the accelerator works, so I don't want to dump a bunch of money into this idea just yet. I figure this solution can also be used with my Plus and a Powerbook 165, possibly all at the same time if I get enough phonenet adapters.
Great to hear @Ton
but given that the engineer I talked to before deciding to do this mod repairs PSUs for a living and tests them at full load for 24 hours before calling them fixed, I wouldn't declare victory just yet...
My recapped PSU died during a small stress/smoke test. My plan was to leave it on idling for 3 or 4 of hours but it didn't even pass the two hour mark...
But your problem is interesting: it means that computers of this era (early 90s) are starting to suffer from tantalum cap failures. Instead of leaking like the electrolytic ones do, those just explode.
And now, back to the subject at hand. I have once again decided to change the fan controller (this will be the last time, as I'm sure this will work this time).
I just can't get enough from the 555 to do everything it want it to do. I'll now be using an Arduino Nano board (it costs from 1 to 7 bucks depending on who you're getting it from... even clones from China should do the job).
I chose it because:
1/ It comes in a PDIP like package. Either solder it to the QuadrATX DC board or install it in a socket. You don't need a hot air station...
2/ It's configurable, because it'll be running a bespoke sketch (read program). If I mess up the code, I can still change it without having to alter the DC board.
3/ It's REALLY easy to flash. Get the free Arduino App for your Mac/Linux/PC, open it, plug in the Nano with a USB cable and hit upload. ANYONE CAN DO IT.
4/ If it dies, there's plenty more available
5/ It's easy to program for and it's got quite a sizable community.
6/ The fan controller part of the schematic is now a lot easier to understand and the circuit won't take as much space on the DC Board as it used to.
7/ Isn't that enough?
More to follow...