HP-27 Repair/ACT/Panamatik LP?

[Maximilian Hohmann]

Thanks Tony

for your analysis! I couldn't finish this straight away because the company called me for a flight but upon returning this morning I was able to revive the calculator :-)

(10-07-2018 04:07 AM)teenix Wrote:  Probably caused by battery gunk.

I guess this was the problem: Battery gunk creating connections where none should have been. All the PCB traces tested OK, even the suspicious ones. After removing the gunk around the ACT chip with a needle and some vinegar and rinsing and drying the board it now seems to work. The piece of ceramic broken off the ACT does not seem to matter. The only problem is the the "1" key which does not register but I hope that this can be remedied with some contact cleaner applied through the holes under the keys. I am very reluctant to take the keyboard apart - better a working HP-27 with no "1" key (one can work around that with some arithmetic...) then one with a totally broken keyboard!

Regards
Max