hp-22

[Alex]

Hello all,I have a hp-22 that has been badly damaged. I was wondering if a schematic available for it- or pin out of the ic's on the board. I compared the 22 vs a working 25 nad the 22 doesn't seem to have -12 volts. Any help would be appreciated. Thank's in advanced

[Viktor Toth]

Alex,

I'm not aware of the existence of an HP-22 schematic (certainly not the chip pinouts; they're all proprietary; how, does anyone have an original HP Service Manual for Woodstocks?) But at least in one case, repairing an HP-25 with a problem similar to yours was surprisingly easy. The cause turned out to be one broken diode in the DC-DC converter; once this was replaced, all voltages were present and the machine was working properly.

Viktor