Fender Hot Rod Deville - Octave distortion effect on More Drive

[dwmorrin]

Agree with 52 Bill.
I'd like to see TP35 get more negative with the panel button pushed in. Are you using footswitch or panel? Maybe stick to panel switching for now. Let us know either way.
Since the pins are so close together in voltage, it is plausible that is why the output isn't swinging all the way.
If pin 2 is negative enough compared to pin 3, output should swing to +16.

With switches engaged, what voltage do you get at C49? Then, as Bill says, check footswitch socket. Maybe its never used and is making a high resistance at the switched terminal. Just try putting a plug in and out there. Should kick it into gear if only temporarily.

[stereomonostereo]

I've got +10 on the side of D21 connecting to R99 and -7 on D25 connecting to C49. At the junction of D21 and D25, I'm getting 1.6. Does that sound low?

[stereomonostereo]

I'm using panel switches when testing. I've got -7 at the negative end of C49. I sprayed the footswitch jack with DeOxit and ran a plug through it and still have the same result

[g1]

How are TP32 voltages? If the problem is that far back, it should affect TP32 as well.

[stereomonostereo]

TP32 is now reading 9.6, and .5, respectively with channel switch

[52 Bill]

TP32 is now reading 9.6, and .5, respectively with channel switch

TP32 is the positive voltage side of the circuit and has been working all along now. This shows that the incoming ac voltage is okay and it's just the negative dc that is still low.

Measure the + voltage at the positive end of C50. Test C49 and R100.

[g1]

Back a ways, 52Bill had mentioned D26 and D24, did they check out? C47?
With TP32 checking out right, I think the problem is after the D23/D24 junction.

Edit: I will defer to 52Bill on the switching circuit, you can ignore this post .

[stereomonostereo]

C50 is showing 10 volts on the positive end. C49 and R100 both test up to spec and I'm getting -7 on the negative end of C49

[52 Bill]

Then test D24, D26, C47, etc. Something is keeping the negative voltage from hitting -10 volts.

[stereomonostereo]

Looks like we found the culprit. D26, which tests good in and out of circuit, isn't. I replaced it with a TZX6V8D, which is all I had on hand, and the +15 is present on pin 1. Thanks a million times over. I was ready to throw this guy in a lake

[52 Bill]

Looks like we found the culprit. D26, which tests good in and out of circuit, isn't. I replaced it with a TZX6V8D, which is all I had on hand, and the +15 is present on pin 1. Thanks a million times over. I was ready to throw this guy in a lake

And is the octave distortion gone now?

[stereomonostereo]

Yep, sounds like it should