Looking for something I'm sure I've seen (25c)

[[kby]]

(06-07-2019 04:31 PM)BobVA Wrote:  I'd be suspicious of the ACT chip, which can malfunction in a surprising number of ways.

If you have some basic troubleshooting experience and the equipment, you might want to check the outputs of the power supply to rule that out. The HP-25 schematic
here has the necessary information.

Power supply seems reasonable; I think(but should re-check as I might be confused with the 29c I'm also working on) that Phi 1 and Phi 2 look OK on the frequency. I'm learning (I think correctly?) that it's hard to get the peak-to-peak values out of a "true RMS" meter since the waveforms aren't sinusoidal—wondering if I'd be better back-calculating them from a cheaper "fake RMS" meter reading.

I'm also considering a 'scope, which I know is what I really need for this and other projects.