Need Help with a Schematic

[maggotspawn]

https://app.box.com/files/0/f/0/1/f_163484884717
Here's the schematic for a 5150 II which is supposed to be the same as the 6505+.
Can anybody tell me what the value for the Gain pot on the Crunch channel is?

[Racing]

For both channels the first gainpot is 1 MegaOhm Audio. Ie; 1 MegaOhm log.
Be adviced that Peavey uses a rather different pot type why it might be a good idea to either order through someone that stocks them or Peavey direct.

You certain the pot is shot?

[maggotspawn]

Thanks for the quick reply. Pot is O.K. I was thinking of swapping it out, if it was less then 1 Meg, a mod which worked on my JSX.
Trying to get a hair more gain on the Crunch channel.

[Racing]

Ah.
There´s other ways around that. If you look at relay K4A and K4B you´ll notice that these are activated in crunch mode only.
As depicted the amp is in clean mode. Ie;the relays shift,vs the schematic,as you engage crunch mode.

This brings that R19 and the small ceramic capacitor across is is jumpered as you engage crunch mode. Instead the signal is routed through a smaller capacitor (vs in clean mode) and heads for VR1.

Then for R23/R174/C63. These are disengaged in crunch mode. All good thus far.

C27 and C151 are in essence bright caps. One across the gain dial and then in turn one across R152,which in essence is the following stage gridstopper. This means that V6A reaches ground for it´s control grid via R154 and VR1 in paralell. This HAS to happen,the grid seing ground that is,for the actual gainstage to reach bias.

Well,R152 and R154 also forms a voltage divider,to an extent. To make the thing go more "oumph" in crunch mode try decreasing R152 to 100k-150k and in turn increase the gridleak,R154 to 1M Ohms. Regular 0,5w resistors will do just fine.
If that doesn´t do it for you consider adding a coupling capacitor between R152 and R154. This will make sure that the bias of that stage will be set by R154 ONLY(you´ll keep more signal amplitude),which will alter behavior of the stage.

Ditto a tad later in the circuit.
R164 and R172 forms a voltage divider as well. Increase value of R172 to taste. It´s 220k stock so try 470k and 1M both,it comes down to taste i´d say.

Mind you,what i mention here are MINOR mods. IOW,what you asked for. "A bit more gain out of the crunch side of things". So nooooo...it will not turn that crunch channel into a Laboga Mr Hector...or a Soldano Slo.. It´ll do what you asked. Nothing more nothing less.

Then an issue arises. If you opt to fool around with the grid setup after that stage,where signal heads for the tonestack eventually,you´ll most likely F up volume balance between the channels. So in essence...don´t. Just leave that be for starters.

IMO the 5150/6505 (yeah yeah..the "II´s" and "+´s" too..) are downright muddy in lead mode. For cleans and crunch..ditto,to an extent.
I´ve played around with this a bit and have had great success from actually TAMING these bitches down! What i mainly do then is decrease the size of the plate resistors-across the entire preamp really-for 100k unison. Them 220k plate resistors might add a tad of amplification but does so at the cost of clarity and attack-no wonder.

I guess what i´m saying,as a whole,is that a few resistors are cheap after all and..the entire preamp easy enough to bolt out of there as a complete package to work on it on a bench. It´s just a few screws.

[Racing]

Oh. Btw.
All resistors and capacitors are numbered on these. Ie;it´s real hard to go wrong.

[maggotspawn]

That all may be beyond my capacity, but thanks for posting. I think Billy is going to buy the amp, so problem solved.