Partially working Symetrix 501 - help!

[focusbob]

Ok, so, the diode checks out. The traces nearby the screw mark seem fine, tested via continuity mode on my dmm. The ratio pot behavior is a bit hard for me to describe so I took a picture of my notes (attached), measuring resistance between each combination of lugs, with the pot at minimum (fully ccw) and again at maximum (fully cw). The scratched out values are both "<1ohm". Does this look normal to you? What was strange to me was that I could not identify a combination of lugs for which the value remained the same while I rotated the pot from minimum to maximum (the closest to this was a pair [2 & 3, I think] that ranged from 4.86k to <1ohm...). Thank you, as always!

[g1]

That seems normal as there is a resistor between 2 & 3 (R94, 5K6). Try one more set of readings with pot set halfway up.
Also, what was the resistance from D16 anode to ratio pot wiper (post #29) ?

[focusbob]

That seems normal as there is a resistor between 2 & 3 (R94, 5K6). Try one more set of readings with pot set halfway up.
Also, what was the resistance from D16 anode to ratio pot wiper (post #29) ?

Will do! One more question though, based on my readings thus far, which pin is the wiper?

[g1]

The wiper is the middle pin.

[focusbob]

That seems normal as there is a resistor between 2 & 3 (R94, 5K6). Try one more set of readings with pot set halfway up.
Also, what was the resistance from D16 anode to ratio pot wiper (post #29) ?

Ok, so resistance from D16 anode to ratio pot wiper = 4.3k

With the ratio pot ser halfway up, I get the following:

1&3 = 23.92k
2&3 = 4.39k
1&2 = 19.71k

As always, thanks!

[g1]

The pot readings look good so it seems to be doing it's job. Check that 'D16' cathode to U7A pin3 is zero ohms.
Do you have a scope?

[focusbob]

The pot readings look good so it seems to be doing it's job. Check that 'D16' cathode to U7A pin3 is zero ohms.
Do you have a scope?

Back in front of this thing after a long holiday

D16 cathode to u7a pin 3 reads 0.5 ohms.

Although a straightforward question (do you have a scope), it does not have a straightforward answer... Yes, I do have a scope. However, I have no idea how to use it (or if it even works properly beyond showing a trace).

[g1]

What I was thinking was to compare what is happening at U7A in compressor mode and compare to what is happening in limiter mode.
That would require looking at the waveform at U7a pin3.
But you will need to be able to use your scope before you can do that. google and youtube can be helpful.