So I got this guitar amp used recently, and it have replaced Bass Potentiometr, but it doesn't works. Its 10K and I wonder, if previous owner put the wrong one. What potentiometr is used for bass in Yamaha GA-15 amp?
Also: it does nothing ?
Or just very little effect?
What if you set treble and mid down to 0 and move just Bass end to end, does it do anything?
PS: post middle and treble pots value.
Or just very little effect?
What if you set treble and mid down to 0 and move just Bass end to end, does it do anything?
PS: post middle and treble pots value.
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It does nothing. And no, turning mid and treble to 0 doesn't change anything.
Treble- A10K. Middle- B500K. Also tho big capacitors near bass are bulged. That also might be a cause, right?
Mayby someone have same amp and could open it and send me what capacitor is for bass is originally used?
Weird.
Most popular tone control, by far, is passive "Fender type" , either with original values: Treble A250k, Middle B10k and Bass A250k
which is often "scaled down" in SS circuits, say T A50k , M B2k, B A50k, to make it lower impedance, but in any case the ratio is bout same: 2 higher value T and B pots, much lower (10 to 20X lower that is) Mid pot.
You have those values reversed, big time, probably by an inexperienced user , and of course it won´t work.
As an example, here is a classic Yamaha Guitar amp schematic, which can be thought of as a "Solid State Fender Twin Reverb" version, notice the tone controls.
Here, Yamaha G20 tone controls, faithful to Fender ones, only 10X lower impedance, meaning 10X smaller resistors, 10X larger caps.
Doubt yours is much different and if it was heavily messed with, copy these values , they will work fine.
the pot values alone in your amp are a mess.
Just in case, use strong light and a pair of reading glasses (to get closer) and draw the tone control in yours, even if missing a couple values we will confirm (or not) what kind of circuit you have.
Most popular tone control, by far, is passive "Fender type" , either with original values: Treble A250k, Middle B10k and Bass A250k
which is often "scaled down" in SS circuits, say T A50k , M B2k, B A50k, to make it lower impedance, but in any case the ratio is bout same: 2 higher value T and B pots, much lower (10 to 20X lower that is) Mid pot.
You have those values reversed, big time, probably by an inexperienced user , and of course it won´t work.
As an example, here is a classic Yamaha Guitar amp schematic, which can be thought of as a "Solid State Fender Twin Reverb" version, notice the tone controls.
Here, Yamaha G20 tone controls, faithful to Fender ones, only 10X lower impedance, meaning 10X smaller resistors, 10X larger caps.
Doubt yours is much different and if it was heavily messed with, copy these values , they will work fine.
the pot values alone in your amp are a mess.
Just in case, use strong light and a pair of reading glasses (to get closer) and draw the tone control in yours, even if missing a couple values we will confirm (or not) what kind of circuit you have.
The factory service manual file does not include a schematic, and the very brief parts list only covers externals - knobs and the handle.
That´s a shot in the dark, you might get lucky but ... I wouldn´t hold my breath.
Do a little homework and trace your tone control. then we can make an educated guess.
Do a little homework and trace your tone control. then we can make an educated guess.
Isn't it enough to find another amp owner and ask to take a photo of schematich? Or is this amp rare?
Your amp your choice.
Less than 1 hour or ..... 🙂
Have you tried searching for its schematic?
What did you find?
Less than 1 hour or ..... 🙂
Have you tried searching for its schematic?
What did you find?
I suspect it is 10KA for bass & treble and 500B ohms for midrange. The bass cap might be between 2.2 to 4.7 uF. Negative to the control.
Suppose the same.
Found G20-G50 schematic and it is very detailed as you say.
Like on all Yamaha stuff.
FWIW, here it is:
As of:
If a Fender type TC that would be the proper ratio between pots.
Maybe somebody replaced it and slapped 500k instead?
Since "all tone pots are in series", that would effectively render TC useless.
As a side note: G20 - 50 - 100 were expensive amps, sporting parametric midrange, active presence controls, a "good" reverb tank, a good Yamaha made speaker, multiple footswitch, etc. , much loved by Jazz players for their clean warm sound.
This one is like a generic "15W practice amp" and yes, sometimes "big brands" rebadge some generic OEM type amp just to fill a niche at the entry level,
Found G20-G50 schematic and it is very detailed as you say.
Like on all Yamaha stuff.
FWIW, here it is:
As of:
Quite possible.
If a Fender type TC that would be the proper ratio between pots.
Maybe somebody replaced it and slapped 500k instead?
Since "all tone pots are in series", that would effectively render TC useless.
As a side note: G20 - 50 - 100 were expensive amps, sporting parametric midrange, active presence controls, a "good" reverb tank, a good Yamaha made speaker, multiple footswitch, etc. , much loved by Jazz players for their clean warm sound.
This one is like a generic "15W practice amp" and yes, sometimes "big brands" rebadge some generic OEM type amp just to fill a niche at the entry level,
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