Bun's Lab
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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.
Recently picked up this General Electric EE7-4325 flip clock radio at a flea market for Eiliko over at https://news.1rj.ru/str/eilikosretrostube
Time to ship it to him :3
Time to ship it to him :3
CRT technology is so incredibly cool and fascinating to me. On the surface, the physics is high school level easy, but tons of engineering went into it to get it to where it was at its peak.