That is a 47uh inductor, here's the schematic
Atari 2600, TI994a, Vic20, c64, ZX Spectrum 128, Amstrad CPC464, Atari 65XE, Commodore Plus/4, Amiga 500
PC's from XT 8088, 486, Pentium MMX, K6, Athlon, P3, P4, 775, to current Ryzen 5600x.
Ohh... I've never seen an inductor that looked like that before. That would explain the strange readings and markings!
Too bad... I was really hoping that I'd found the problem. I still can't figure out what that red component is.
Now for some blitting from the back buffer.
Just bumping this to see if anyone has any more input. I've done some more work on my old 5150 and it is working beautifully... but they keyboard I'm using leaves a lot to be desired. I'd love to use the old Model F, but haven't made any progress toward fixing it.
I have attached a .zip containing a .bin file that I've been told (by someone who works on these keyboards) is the proper firmware for this keyboard. So if anyone has a means of getting this onto an appropriate chip, or any advice on how I could do it cheaply, I'd be most appreciative.
Also, any other possible leads on random stuck key errors could be helpful.
Now for some blitting from the back buffer.
Yearly bump.
Still looking for anyone who has the ability to program an 8748 with the firmware attached to my previous post. PM me if you have the ability to do this. Also, as before, any other suggestions to fix the problem would be nice.
Now for some blitting from the back buffer.
SaabFAN on EEVblog built a small 8741 programmer for the Arduino Nano: https://www.eevblog.com/forum/microcontroller … icrocontroller/
TimInCanada has a followup that works for his 8748: https://www.eevblog.com/forum/repair/intel-87 … g-with-arduino/
Ozzuneoj wrote on 2019-01-20, 01:46:Yearly bump.
Still looking for anyone who has the ability to program an 8748 with the firmware attached to my previous post. PM me if you have the ability to do this. Also, as before, any other suggestions to fix the problem would be nice.
Hello,
I've faced the same problem, my IBM F XT Personal Computer keyboard has failed. All the clues show that the controller is a culprit.
Thank you for the ROM image. Also, I've obtained another one. I was said it was grabbed from the UK version of the keyboard; and it turned out two images are absolutely the same. So, probably, yours is of the UK version, too.
Anyway, I'm going to program the controller with this ROM. I've found a Moscow guy who has chips for sale, and is agree to program them on demand. The chips are not genuine Intel D8748H, but their Russian clones, KM1816BM48. Functionally, clones are absolutely the same, but, according to Soviet standards, the distance between legs is a bit shorter (2.5mm vs. 2.54mm). So, for 20 legs the furthermost one will be .76mm off-center. It's quite much, but, acting accurately, it's possible to fit the Soviet chip into the footprint of the standard one. I've done it before, and it's totally doable.
If you wish, I can send you the programmed chip by mail, just let me know.
Sincerely yours,
Peter, Russia
