Treble Bleed Circuit Not Working

[solderburn]

Hi there,

I hope someone here can give me the answer to why this treble bleed circuit isn't working in my Squire Jaguar. I feel very stupid, this should be a simple mod, and I've done it with two other Jags without any issue, though they're both American made, one of which was a parts build that I did.

I'm not sure of the value of the stock volume pot, but I assume it's 1 MEG, as is standard in Jaguars. The treble bleed is an Emerson made 470pf polystyrene capacitor and a 220k resistor cap in parallel.

Here's where I'm at now: I've installed the two different, exactly the same TB circuits, both are giving me the result of making the volume knob sound like a tone pot, the sound seems even more muffled than without the TB circuit! The volume stays relatively unaffected until the last 10% or so, then abruptly drops of to zero volume. I've re-flowed the joints, I made sure it's not touching anything else. I've replaced it. I'm not sure what I can do from here. I'm considering replacing the pot to an Emerson 1MEG pot.

I'm hoping one of you can make me feel more like an idiot, and tell me that I'm just doing something obviously wrong.  Thanks!

The TB circuit...




How it looks without the TB circuit...




With the TB circuit installed. 

[Yogi B]

Jun 8, 2022 21:44:09 GMT -5 solderburn said:

The volume stays relatively unaffected until the last 10% or so, then abruptly drops of to zero volume.

Was this also the case before adding the treble bleed? (I suspect it was, based on what I think's wrong, but it's not perfectly clear from your description.)

Another thing to clarify, the green cable on the tone pot goes to the lead/rhythm switch on the upper control plate, and the red cable on the volume comes from the lead toggle switches on the lower switch plate, correct? (That's what I'd expect from typical Jag wiring.)

If the above is true, then it means for whatever reason that the volume control is wired 'backwards', as an independent volume. Does the guitar have the usual Jaguar control setup? (The usual reason for independent wiring is on something like an LP, or keeping it in the Fender family an original Jazz Bass, where each pickup gets a separate volume.)

The fix is to swap the black wire on the centre lug of the volume with the white wire on the outer lug. That, by itself, should fix both the taper and the tone loss at lower volumes — though the treble bleed will obviously be helping too.

[solderburn]

Yogi, you are 100% correct, not surprisingly.  THANK YOU.  I knew I'd feel like an idiot, but that's ok, because now my guitar works as it should.  You're awesome!   

I'm such a doofus, i even took pics of how everything was before i started, and I just re-looked at them, it was wired correctly, then when i wired in the TB i swapped the locations.  I can't believe it.  

[unreg]

Jun 9, 2022 0:09:20 GMT -5 solderburn said:

even took pics of how everything was before i started, and I just re-looked at them, it was wired correctly, then when i wired in the TB i swapped the locations.  I can't believe it.  

If you draw a wiring diagram on paper, while it takes a bit more time, you can easily look at the finished diagram to see where colored wires go.

You could even make a key for Y == yellow, B == blue… something like that, so then the color notations take much less room.


Plus, it’s easier looking at 1 wiring diagram than at many different pics. It’s also much simpler since the wires in a wiring diagram aren’t hard to see.

[solderburn]

Thanks unreg, that's an excellent suggestion. I'll start doing that.

[thetragichero]

cap reads 470 which generally means 47pf. might it just be too small to notice? assuming 500k pots at half rotation (okay i just used 250k for sake of calculation) rc filter calculator gives me 13khz for what a 47pf bright cap would pass. I'm ignoring the parallel resistor here but that's like 3x any useful guitar frequency

[Yogi B]

Jun 16, 2022 16:20:36 GMT -5 thetragichero said:

cap reads 470 which generally means 47pf.

True, but it seems that polystyrene caps tend to be labelled in pure picofarads, rather than the usual three digit code.