HP-35 power unit: Failing Vgg voltage

[teenix]

(11-09-2022 10:58 PM)robjordan Wrote:  Thanks for the quick response.

Regarding replacements - do you suggest replacing capacitors with the Kemet T110, which seem to still be available? And the diodes: should they be germanium? I think saw someone recommended Schottky as an alternative with similar forward voltage drop.

T110 would be good (albeit expensive) if you want to replace the caps with original looking ones, or Kemet 322 a bit cheaper, or Vishay axial even cheaper.

Can't see why the Schottky's wouldn't work as long as the specs are similar. You might just see a slight change in the output voltages. Bat46 maybe?

Transistor equivalents for

1554-0550 - 2N3904
1853-0020 - 2N3702

Depending on the power supply design, I think the later versions changed from PNP/NPN to 2 NPN's like the HP-45.

cheers

Tony