HP-97S BCD POD - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html) +--- Forum: General Forum (/forum-4.html) +--- Thread: HP-97S BCD POD (/thread-1338.html) |
HP-97S BCD POD - ignazio - 05-17-2014 08:37 AM Hi, who can help me to restore a bad BCD pod? It has the control PCB bad. There is a repair protocol to find the bad components? Thanks for your contribute. RE: HP-97S BCD POD - Katie Wasserman - 05-17-2014 04:47 PM (05-17-2014 08:37 AM)ignazio Wrote: Hi, Almost all of the IC's in the pod 4000 series CMOS or 74C series and are still readily available and very cheap. I helped my friend repair his without having a schematic by doing the following simple technique: 1) Swap the main 24 count IC board with a known good pod to determine which of the two boards had the problem. (It sounds like you already did this step.) 2) On the bad board, de-solder (with a nice de-soldering tool) each IC and test it with a IC tester (look around the internet, almost any one will do 4000 series and 7400 series chips and they can be bought for $40US or so). 3) Replace the IC's that don't identify on the tester. We found a bad 4043 chip, we knew this one becasue it was labeled MC14043B. But the HP part numbers on this board are easy to find in cross-reference lists. On the main 24 count IC board only the one labeled 1818-0565-1 is not a standard IC, I think it's a ROM. Of course the "better" way to do this is to get a hold of Tony Duell's schematic and debug it with a logic probe. But I think that that could take considerably more time as this is a complicated circuit with much of it only functioning based on the BCD input you'll need to provide. RE: HP-97S BCD POD - ignazio - 05-18-2014 04:39 PM Hi Katie, Thanks for your advices, I'm awaiting for a IC tester purchased today. Regards from Italy. |