Peavey Forum

The center pin in the PCB layout clearly is the wiper, and it would be quite an unusual pot where the wiper is anywhere but on the center pin. Thanks, dak. It's going to be next week before I can get back to this, But either the center pin is ground, or I tested it incorrectly. I'll grant that the ...

dak wrote: ↑

Thu Oct 06, 2022 8:55 am

Well, swapping wiper and upper end of the pot would have about the effect you talk about.

Does this mean that I should swap the left and right wires on the pot (I’m pretty sure that the center post is ground)?

check whether adjacent contact points on your pot are connected when it is in the middle (then they shouldn't) or when it's at min or max (in which case the wiper should be in contact with the respectively correct side of the pot). Thanks for the clarifications, dak. I tested the continuity between...

Thanks, dak. Yeah, it's not my finest job. I tested continuity from the pot to the forward leg of the first resistor in each path. Pic attached to show the points). None of them registered resistance of more than 0.5. Is there something else I should measure?

Thanks, dak. I'm not saying that I couldn't possibly have fried a pot, but given the iron I'm using, and also that I've tried two different ones (three if we count the 10k pot), I don't think it's the most likely culprit. I redid my solder joints. No change. I've attached pics, and am open to critic...

dak wrote: ↑

Sat Oct 01, 2022 4:40 am

Stupid question: what's your soldering setup?

Not stupid at all.
I'm using a Miniware TS100https://www.miniware.com.cn/product/ts1 ... g-station/. It's adjustable in ten degree increments. I'm using it between 300-340, as needed.

Thanks dak and Pappy, I'll look into these possibilities and report back. I did try a second 1M pot after I had trouble with the first, but they were from the same package, so I guess could be a bad batch (they were Amazon cheapies). I'll look at option #2 first, since it addresses user error, since...

checked capacitor C13 to see if it is shorted? Thanks for checking on this, Pappy. I put the 1M log pot back in, and lifted one leg of C13. Pretty much the same story- Vol pot still doesn't do anything, but now, instead of being at full volume, it's at about 0.5. Does that tell us anything? When I ...

Sorry dak, I should've followed better.

It behaves just as Pappy says it should- the Clean volume pot does not affect the Lead channel (or the Clean channel, which of course is the problem), and the Pre and Post pots don't affect the Clean channel.

dak wrote: ↑

Sun Sep 25, 2022 6:42 am

Does the post lead pot have any effect on the volume?

Yes, when on the lead channel, both the pre and post affect the volume. Vol pot still has no effect.

Ok, so clearly from the photographs it would be the schematics you posted that are relevant, so that would make it a 1M log pot. Sorry for the confusion. If C13 is shorted (part defect or solder bridge), that would explain your problem. You could try just removing it for a test: I may be mistaken b...

OK, I soldered in a 10K linear pot, and have the same results- when on the clean channel, the amp is a full volume, and turning the knob has no effect.
Not my first soldering job, and the joints look clean, but could that be an issue?

A photograph of the controls might give more of a clue which schematic might be relevant. I tried to post some pics yesterday, but I might be too new / not have enough posts. It's definitely a silver stripe transtube. The underside of the PCB has a few sets of numbers and words embedded in it, incl...

dak wrote: ↑

Fri Sep 16, 2022 1:51 pm

A photograph of the controls might give more of a clue which schematic might be relevant.

Here's the front, and both sides of the PCB. Thanks for your continued interest in this.

Thank you both; I'll try a 10K linear.

Pappy, we must've seen the same schematic.