Bun's Lab
Yeahhh .. that would have popped
I would've liked to put this to a test and pop it on camera but my power supply goes into over current protection.
Old vs new tantalums. If you don't feel like replacing tantalums with tantalums, I think you could also go for some nice modern polymer low ESR caps instead. The reason tantalums were used in the first place was because of their low ESR compared to normal electrolytics at that time. Correct me if I'm wrong, but that's my theory.
Bun's Lab
Ordered parts! I hope I can finally break through my giant backlog
I feel like a kid at Christmas
Check out Atkelar's channel. Really in-depth restorations, but with a qt furry twist.
https://www.youtube.com/user/atkelar
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Bun's Lab
Today on the bench.... yet another 286 board. Objectives here are to shotgun replace the tantalums, test it, fix any issues, then pack it up for its new owner
That's done. Ready to be shipped to its new owner
Bun's Lab
Photo
Another look at this. And I think the chipset and/or CPU is toast. There isn't much else on the board that could die from ESD, and a bus local to the chipset and CPU shows those runts. Guess it goes into the parts bin 😢
Bun's Lab
Ok I'm bummed out now. My 286 broke. This one:
I gonna put this board in there now. 20Mhz Harris 286.
Bun's Lab
I gonna put this board in there now. 20Mhz Harris 286.
Ok so, this board was working when I last touched it. Now it's not. No beep, no video output, nothing, not even anything on the POST code card, just - - - -
Clock is there, activity on the bus, the CPU is not being halted. Activity seems to be a very tight loop.
Replacing the CPU, RAM, does nothing, so does messing with the jumpers. BIOS EPROM reads out fine, but I have yet to check the parity checksum. Replacing the keyboard connector also does nothing, BUT, if it's out, it starts up.
Cold start results in a short beep, with the message "8042 GATE A20 ERROR SYSTEM HALTED" (of course it's unhappy about a missing keyboard controller), with POST codes being (in reverse order):
43 42 41 40 3b 3a 39 38 37 36 35 2e 2d 2c 2a 29 28 26 25 24 22 21 20 15 14 13 12 11 10 0f 0e 0d 0b 09 07 06 03
A soft reboot results in black screen and 7 short beeps
Clock is there, activity on the bus, the CPU is not being halted. Activity seems to be a very tight loop.
Replacing the CPU, RAM, does nothing, so does messing with the jumpers. BIOS EPROM reads out fine, but I have yet to check the parity checksum. Replacing the keyboard connector also does nothing, BUT, if it's out, it starts up.
Cold start results in a short beep, with the message "8042 GATE A20 ERROR SYSTEM HALTED" (of course it's unhappy about a missing keyboard controller), with POST codes being (in reverse order):
43 42 41 40 3b 3a 39 38 37 36 35 2e 2d 2c 2a 29 28 26 25 24 22 21 20 15 14 13 12 11 10 0f 0e 0d 0b 09 07 06 03
A soft reboot results in black screen and 7 short beeps
Ok so scoping that out, VCC and Ground on the keyboard controller looked like a data pin. Someone suggested I have the sockets mixed up, and yes I did. The keyboard controller goes in the other 40 pin socket, the one furthest from the keyboard. Of course it does!
(I had this out before to test a different board with, seems like I didn't pay attention. And of course the sockets are not labeled)
I feel so dumb. Real bun moment. No brain, just fluff.
(I had this out before to test a different board with, seems like I didn't pay attention. And of course the sockets are not labeled)
I feel so dumb. Real bun moment. No brain, just fluff.