Caps in series??

[dumbassbob]

If you have 2 caps 250pf CD and a 350pf SM in series,but the 350pf has a wire running parallel with it..Wich wire will get the voltage? the plain wire or the 350pf..Years ago someone put the 350pf on top of the wire going to the 250pf to tone pot on my 63 bandmaster,It sounds fine,but is it adding more voltage to the tone pot....

[R.G.]

I don't understand your question.

Can you draw a picture? I can't picture where the wire runs and what it's connected to. The answer is simple once I can figure how how it's connected.

[Jazz P Bass]

A capacitor 'on top' of a wire?????

If the capacitor is in parallel with the wire, then the circuit resolves simply to 'a wire'.
The capacitor is ignored.

[Malcolm Irving]

Yup, and 2 caps in series (if the parallel wire is disconnected) works differently to resistors. 250pF in series with 350pF becomes 1/(1/250+1/350) = 146pF.

[Justin Thomas]

So for my own personal use, a cap is only useful for tone shaping if it's across a resistor, and not a bare wire, right?

I reckon it would do no harm to simply lift one leg of the 350pF cap and see if it changes the sound at all... According to Jazz, it shouldn't, right?
Justin

[Malcolm Irving]

So for my own personal use, a cap is only useful for tone shaping if it's across a resistor, and not a bare wire, right?

I reckon it would do no harm to simply lift one leg of the 350pF cap and see if it changes the sound at all... According to Jazz, it shouldn't, right?
Justin

Yes, that's right.

[dumbassbob]

just look at a schematic of a ab763 bandmaster from pin #1 to plate (R) there is a wire under the board going to the 250 pf cap to treble pot someone put a 350pf sm cap over that wire years ago and I wanted to know if it raised the voltage,or why they did this...

[nickb]

just look at a schematic of a ab763 bandmaster from pin #1 to plate (R) there is a wire under the board going to the 250 pf cap to treble pot someone put a 350pf sm cap over that wire years ago and I wanted to know if it raised the voltage,or why they did this...

The wire goes from the plate to the 250pf ceramic disc cap. Between which two points does the 350pf silver mica connect to?
Have you checked to see if the wire is still intact i.e. could it have but cut through - check with meter on ohms range?

[dumbassbob]

The wire goes from the plate to the 250pf ceramic disc cap. Between which two points does the 350pf silver mica connect to?
Have you checked to see if the wire is still intact i.e. could it have but cut through - check with meter on ohms range?

over the dotted line it is conected will it do anything

[J M Fahey]

So for my own personal use, a cap is only useful for tone shaping if it's across a resistor, and not a bare wire, right?

I reckon it would do no harm to simply lift one leg of the 350pF cap and see if it changes the sound at all... According to Jazz, it shouldn't, right?
Justin

If a cap is "across a bare wire" it's shorted, so no longer a cap.
It's irrelevant whether it's in a tone control or anywhere else, it's not a cap anymore.
Of course leaving both legs soldered to that wire or lifting one up in the air will change nothing, because in that case, it becomes a cap again, but an unconnected one.
Anyway we are just wildly guessing at the poorly written dumbassbob question.
EDIT: just simulposted with dumbassbob: ok, it's confirmed that "across" means "in parallel/shorting" .
In that case resulting capacitance is 250 pF .

[dumbassbob]

A capacitor 'on top' of a wire?????

If the capacitor is in parallel with the wire, then the circuit resolves simply to 'a wire'.
The capacitor is ignored.

Thanks I got my answer

[nickb]

over the dotted line it is conected will it do anything

Use your meter to see if the wire is still connected. It will read close to zero ohms if it is.

If the wire is open circuit then the 'capacitors in series' rule applies.
If the wire is intact the the 350pf is shorted out and only the 250pf is doing anything.

[Chuck H]

Is this the amp that Gerald Weber was goofing on!?! Is this the amp that Hendrix used?

It's not hard for me to imagine even someone green enough to put a cap parallel to a wire leaving it that way after a listening test. But I have a hunch there is something going on you haven't detected.

I think you need to make sure the circuit is actually wired as you describe. Ignore the schematic. What is in the amp. I know you can see a 350pf cap in series with the 250pf cap. Have you tested resistance across the leads of the 350pf cap to see if the "wire" is connected as drawn in the schematic? Is there, by chance, a switch involved with this circuit that we don't know about?

How about a photo?

[dumbassbob]

Is this the amp that Gerald Weber was goofing on!?! Is this the amp that Hendrix used?

It's not hard for me to imagine even someone green enough to put a cap parallel to a wire leaving it that way after a listening test. But I have a hunch there is something going on you haven't detected.

I think you need to make sure the circuit is actually wired as you describe. Ignore the schematic. What is in the amp. I know you can see a 350pf cap in series with the 250pf cap. Have you tested resistance across the leads of the 350pf cap to see if the "wire" is connected as drawn in the schematic? Is there, by chance, a switch involved with this circuit that we don't know about?

How about a photo?

the 350sm cap has been on it for the 45 yrs I owned the amp G.Weber took it off I put it back on after he shotguned the amp and pulled all the blue caps out..All that was wrong with the amp and I found it was the power tube plate wires were reversed..But someone yrs ago put the dommino cap across the bare wire going to the 250 pf cap that goes to the treble pot,sand did this really Do anythingThe bre wire under the board going to the 250 cap is hooked up..It seems like a simple question...I was just worried about the voltage would it double it to the treble pot...The Amp sound great..I play it every day for 11/2 hrs...I can't find the old thred How to fix a 64 Bandmaster it has all the pictures and the factory 3 plate resistors

[Chuck H]

the 350sm cap has been on it for the 45 yrs I owned the amp G.Weber took it off I put it back on after he shotguned the amp and pulled all the blue caps out..All that was wrong with the amp and I found it was the power tube plate wires were reversed..But someone yrs ago put the dommino cap across the bare wire going to the 250 pf cap that goes to the treble pot,sand did this really Do anythingThe bre wire under the board going to the 250 cap is hooked up..It seems like a simple question...I was just worried about the voltage would it double it to the treble pot...The Amp sound great..I play it every day for 11/2 hrs...I can't find the old thred How to fix a 64 Bandmaster it has all the pictures and the factory 3 plate resistors

I can't help but remember that the amps old mojo was never recaptured. My guess would be that the 350pf cap was part of a mod circuit that Weber undid. Later, attempting to restore the magic, you put the 350pf cap back as best you could figure it was installed before Weber got his hands on it. Basically... What we now know is that before Gerald Weber attempted to restore the circuit there was a 350pf cap in series with the 250pf treble cap. Are you certain that in this condition there were no other wiring differences? Or do you assume the 350pf cap was paralleled by a wire because that's consistent with the schematic, and the way Gerald Weber returned it to you with the 350of cap removed? It's all very confusing now, isn't it? I don't imagine anyone doing circuit mods for JH put a 350pf cap across a fixed lead. I further speculate that if that amp displayed a difference that appealed to JH that it's possible there WAS a difference in the circuit and Gerald Weber undid it.

For your consideration.