Restoring a HP9830B calculator.

[MattisLind]

Yes, I have your data file. Excellent!

Yesterday I was about to trace the signal on the data path board at U19 when I discovered that there were no U19 on the board! I never checked that it was the same board as in the schematics. I just presumed them to be identical. The boards in my HP9866 differes in that the data path PCB is 09866-66591 and the Control PCB is 09866-66592.



The Data Path PCB has a different character encoding ROM, SCM3632 from Motorola, with HP ID 1818-0167. It uses two Texas Instruments TMS3120 quad shift registers rather that three MM5052. I haven't traced the board yet, so there might be a lot of other differences, but I guess that what HP did was to upgrade to more modern parts. It could be as simple as that they replaced three MM5052 with two TMS3120 there would be only 18 ICs on the board compared to previously 19?

I assumed that HP only changed the board layout, not the backplane connections: A quick check for the RotEn signal on the Data Path PCB reveal that it comes from pin 6 of a U8 which is a 1820-0071 chip. Google says this is a 7440. It matches pretty well with the HP9866 schematic Tony has made.

Tony, do you have a translation table for HP part numbers into standard part numbers?



The control PCB. I cannot tell what difference this board has. But the micro code ROM is the same HP part number so what was found in the previous post has to be correct. That would also mean that the same inputs and control codes to the 74150 is used. I need to trace the board to verify though. Tony, how does this match the 09866-66502 board, just from a quick ocular inspection?

The next step would be to measure on the Data Path PCB at U8, U3, which is the 7490 and U13, 1820-0174, which I assume is the 7404.

BTW. Both images are clickable so one can get the full size image..