Just above the probe connector is a switch for AC or DC coupling.  In the pic, you have it set to AC.  That is why it will not hold the DC offset, you need it to be set for DC coupling.
It is not that often that I use DC coupling on my scope, but useful for some things.  Generally I use my meter for DC measurement.

Yes, tracing through the preamp with scope should enable you to locate the fault.
You need to highlight the signal path on the schematic and check points along the way with the scope.  But you also need to have an idea of what to expect, as the signal level may normally go up and down along the way.

 They have range of DC voltage at Q101 source shown (.5 to 2V), I think that should follow the pot setting.
(copy/paste from MEF  )

Quote from: saturated on August 25, 2023, 07:46:39 AMin the grand scheme of things i have a long way to go ha ha

but every journey begins with a single step

You have no idea how many people just refuse to learn the basics and start at the beginning.
It is the #1 most important thing you can do, so you are off to the best start you can make.   

Quote from: WimWalther on July 31, 2023, 12:41:12 AMThough, the tap box has two different TRS jacks - one specific to the BE Dlx and the other for 3rd party devices.

I did not realize it had 2 types of jacks.  My assumptions were based on the idea it used the same jack for it's own unit and for other brands, so those assumptions are flawed.

If you have the main unit, you should be able to plug in a TRS cable and see what is what just by momentarily touching terminals together with a jumper.

I don't have the wiring, but it is supposed to work with other units as well.
So I expect tip to sleeve as the momentary tap switch, and ring to sleeve for the LED.  Possible there is a resistor on the LED.

Nothing going on except momentary switch and LED.

Quote from: pontiacpete on July 21, 2023, 12:30:33 PMSo when I plug into the effects return with the boost down it is the same level of distortion as in the input.

In both the high and low amps, or just one of them?

Quote from: tysonad on July 19, 2023, 03:47:22 AMHello, thanks for this thread, I was delighted to find it but then I saw that your drawings had been taken down.

The missing pictures have been added at the bottom of each post (as attachments).  I don't know how you could actually miss them.

Why is that 204-0104-c pdf schematic labelled as such (posts #1 and #10)?
It is clearly marked 'Rev.D'.  All copies should be corrected and posts should be edited.
Pontiac Pete, if you have the pdf version that those jpg's came from (real Rev.C), please post it.
Otherwise, I am attaching Rev.F which includes the preamp.  It should be the same circuit, although component names may be different like in the power amp.

I think the Cap at pin8 of 3886 IC only gets reverse voltage when the chip blows.  So they probably went to non-polar cap to deal with that.
The polarized ones were probably getting damaged but overlooked when IC blew, so going with non-polar eliminates that possibility.  Normally, 'Mute 2' line would only have negative voltage.

Try using 'FX Return' jack as input, and make sure 'boost' is turned all the way down.  Still distorted in both amps? 

J1 should be a thermal breaker somewhere, it opens if the amp overheats and triggers the shut-down circuit.  The other schems show it as 85 degree C.

You have distortion, is it in the low amp, the high amp, or both?
R9 is a critical adjustment.  If you did not put it back exactly where it was, the amp may overheat.

With Q6 removed, do you still measure the short at the traces?

Peavey uses several methods to connect circuit ground to chassis.  Sometimes jacks, sometimes pot brackets, sometimes the screw posts touch a trace or wire jumper.
Partial or full disassembly of any unit can result in lost connections, it can be quite complex in some of the more modern stuff, for example some Yamaha mixers.

I guess there is a panel switch to select between clean/dirt channels and you want to toggle between lead and ultra?  Then yes, grounding FS jack pin 2 will do so.

Check R120 and it's connections.  Measure resistance from that 1.5V line to ground.
The 2SC1730 basing is ECB, the BC547 basing is CBE.  Otherwise it should be ok as sub.

2SC3478 is ECB pinout, MPSA06 is EBC.
Find out which pinout is correct by following the traces to D4, R21, and R85.
Then tell us where the short is located on the board.