Ampeg SVT oddity

[Valvehead]

I came across something odd last night at a gig. Ive been in live sound for many years and Ive never seen this......

Rack mounted SVT Pro 3 . I was using the Xlr out and strangely , the Xlr out level pot on the back was controlling the amps volume out of the speaker cab . The pre/post switch on the front didnt change anything.
This has got to be a fault with the amp yes ?? Anyone ever seen this ?

[glebert]

Do you have a schematic? I'm having trouble finding anything other than the power amp schem.

[TomCarlos]

Very odd... That level adjust is a pull switch to lift the ground. I wonder if there is something funky happening with that switch shorting something?

Manual - SVT_3PRO_OM.pdf

Schematic - SVT_3Pro_Schematic.pdf

[glebert]

It looks like this one is the Full Schematic and Board Layout - [ATTACH]n985479[/ATTACH]

Although the file is named 3 Pro that seems to be the schematic for the SVT III, which is totally different circuit I believe.

[TomCarlos]

Thanks Glebert... I deleted that post with the full schematic.

[Valvehead]

ok...i have the exact model wrong. the model above looks slightly different.. Ill ask the owner. It looks very similar..i know its an older amp