Biasing a Red Rooster

[brandon cur]

Hey guys,

I'm new here - apologies if this is the wrong section, it seemed most appropriate for what I have to ask.

I recently acquired a DAM Red Rooster - but the trim pot had been messed with. I have a multimeter but am a complete noob (saving money for my first kit to start learning).

Can someone give me a layman's guide on how I could reset it to the stock 6.66 volt value? Not even sure where to probe or what setting to put my DMM on.

Here's a pic:


Any help would be super appreciated!

Thank you,
B

[andy-h-h]

Hello

I guess first off, you can adjust by ear.  Crank up the boost and adjust to where it sounds the best to you.

But to answer your question:

If this is a PNP version, the bottom row is ground, so this is where the black (negative) probe is to be placed - or anything connected to here, like the ground connections on the input or output jacks if this is more convenient.

You want to measure DC voltage on the collector with the red probe, which is the blue transistor leg at the top of the board.  If you can't access it due to the tubing, it also connects to lug 3 of the boost pot.

With the probes connected adjust to suit.  I think they adjust with the boost cranked?  You'll work that out soon enough.   

Once you have it at the magic 6.66v try adjusting it again by ear and see what you prefer

Good luck