Mystery "clipped" wires in Bassman 135?

Off the top of my head, looks like the screen supply node for a non-ultralinear output transformer build. No idea why they'd leave those wires there in that state though.

 

I'd remove them for safety reasons.

 

Take them out. You'll have 400V sitting on the end of those clipped wires just waiting for someone to be poking around inside the cabinet.

 

Yikes!

 

The amp chassis was probably used for other model heads, and these were for other circuits, reverb, tremolo, but cut off when used in a bass amp.

 

Any of those circuit using high voltage would have been chassis mounted, not external. Even in those days, they were cautious about leaving high voltage contact points out in the open.

 

Somebody may have been experimenting with the amp. I believe it's fairly common to disconnect the screen taps from the output transformer, so those wires may have been used to form a 410V screen supply.

Note the screen connection for the Bassman 100 is essentially at the same point.


I also found a thread that says the assemblies were shared with other models that used the wires for reverb and tremolo circuits. The thread suggested cutting them out: https://www.thegearpage.net/board/index.php?threads/83-bassman-135-cut-wires.1363720/

Here's a link to the 135 amp schematic with reverb and vibrato: http://acruhl.freeshell.org/mga/schematics/amps/late70s135w.jpg

 

Then leave it alone!

 

Amp Guts Photos - Official Thread - Lets see those pics

Same clipped wires, and lots of space for extra circuits on the eyelet board.

 

Measure the voltage at them.