Bass Potentiometer ?

[gtrplayr1976]

I have a bass pot that should be 250K ,but only reading 210K. Would being that far off cause an issue ?

Thanks folks.

[pdf64]

Unless otherwise specified, pots seem to have a default tolerance of 20% for the track resistance, so it's almost certainly within the manufacturing spec.
Assuming that the application is a regular Fender type tone stack, as it's a 10% audio taper, I can't think that when set to max, 210k would be noticeably less bass than 250k.
Download Duncan's TSC to investigate.
Pete

[gtrplayr1976]

Unless otherwise specified, pots seem to have a default tolerance of 20% for the track resistance, so it's almost certainly within the manufacturing spec.
Assuming that the application is a regular Fender type tone stack, as it's a 10% audio taper, I can't think that when set to max, 210k would be noticeably less bass than 250k.
Download Duncan's TSC to investigate.
Pete

I'm just trying to figure out why the Vibrato channel on this SF Twin is so thin sounding ,and doesn't seem as loud at the normal channel. The pot is the first thing I noticed that was off some.

[pdf64]

Maybe the cathode bypass caps have developed excessive series resistance?
Try dabbing a good one across them to see if a gain boost results.
Pete

[gtrplayr1976]

Maybe the cathode bypass caps have developed excessive series resistance?
Try dabbing a good one across them to see if a gain boost results.
Pete

Pete, the caps are new ,but I guess it doesn't mean one can't be bad. I tested them yesterday ,and it showed 22uf. I'll try what you said.

[Bruce / Mission Amps]

Is the bright switch in that channel functioning correctly?
That +100pF brite cap can really shock the upper mid and treble hard!

[Jazz P Bass]

Is the bright switch in that channel functioning correctly?
That +100pF brite cap can really shock the upper mid and treble hard!

I thought the same thing but didn't type it.
A scope & a signal generator would come in handy for this one.

[gtrplayr1976]

Is the bright switch in that channel functioning correctly?
That +100pF brite cap can really shock the upper mid and treble hard!

It changed tone when I switched it. I guess I could take it out of the circuit ,and see if it's any different ?

[gtrplayr1976]

I thought the same thing but didn't type it.
A scope & a signal generator would come in handy for this one.

Hey Jazz ! I've been accumulating test equipment. Unfortunately none of it is in working order yet. The scope arrived damaged ,and I await another one. I have a signal generator ,but I need to test it to see if it works. Fact is I may have a bunch of spare parts

[Jazz P Bass]

It changed tone when I switched it. I guess I could take it out of the circuit ,and see if it's any different ?

Nah.
The switch itself takes the cap out of circuit.

[gtrplayr1976]

Nah.
The switch itself takes the cap out of circuit.

Yeah , I was just thinking if I disconnected it completely it wouldn't be an issue. I think I actually replaced that switch ,and cap at one time.

[gtrplayr1976]

Is the bright switch in that channel functioning correctly?
That +100pF brite cap can really shock the upper mid and treble hard!

I thought the same thing but didn't type it.
A scope & a signal generator would come in handy for this one.

I think this was it . I disconnected the bright switch completely ,and there is a world of difference. I also found the wire connected from the bright switch to the volume control hanging by a thread. I will reconnect the switch this evening ,and go from there.

Thanks gentlemen !

[gtrplayr1976]

Working much better now ,and I also found the bias was way off causing bad distortion. Thanks all !

[gtrplayr1976]

I still seem to be having issues with the Vibrato channel. Maybe the bright switch is just bad. I swear when I disconnected it it was back to normal. I may have to try it again to see if I was hallucinating. I also had a very bad hum with the Reverb on. Found a broken wire in the tank, fixed that. Reverb works ,but still has a hum when it's switched on. What would cause hum in this ?

[pdf64]

Is the footswitch plugged in?
If so, try unplugging it.
Pete