HP 67 Power Supply (not oscillating)

[mbielman]

I have a 67 logic board here that I'm trying to set up as a test unit. At this point, it has no ROMs installed other than ROM0. ACT and CRC are installed.

Problem is the PS isn't working. No oscillation. So Vcc is nearly at Vbat and no Vgg.

But it WAS working! Components measure 'OK' in-circuit. (no shorts) Vcc not shorted, etc.

Wondering... does the PS need the load of the ROMs to run? Seems odd to me. If so, what is the expected load current?

Any thoughts?

Mark