YGL 3 Issue with Master Volume

[Mr_bibbles]

Hey Guys! I have a headscratcher. Have a YGL 3 that was previously modded, I had to switch out some parts and I may have disconnected half of the Master Volume. To clarify, the Master Volume works perfectly for the second channel, but the first channel acts as if it were totally independant of the master. Volume / tonality is good across the board, I'd just like to hook up the first channel into the master volume!

So, my question is, can someone explain how this Master Volume works? I'm assuming the Channel A signal is sent to master after V1B Grid through the .022 Cap and the 100k Resistor? I've checked the caps in and resistors in this block leading up to the PI but can't find anythign wrong..

YGL 3

Any ideas as to what could be causing the disconnect?

Thanks in advance,

Mr. B

[The Dude]

Reattached schematic with proper orientation.

[g1]

If both channels were going through the master before you did your recent work, then you did something to change it.
What parts did you replace?

[The Dude]

The first order of business, IMO, is to verify that your amp is the same as the schematic. In my experience, there are lots of Yorkville schematics that don't quite match up to the actual thing in front of you. Assuming the drawing is correct, I would look for something disconnected or bypassed. Since it's been modded, see any extra wires, anything missing, etc. Undoing mods can be a giant PITA, which is one reason I hate them.

[nickb]

My guess is you wired R9 or R11 incorrectly. You should go through and carefully check your changes.

There is nothing unusual about the MV: CW pin is input signal, CCW is ground and wiper is the output. Just looks a bit weird due to the screened cable.

[Mr_bibbles]

My guess is you wired R9 or R11 incorrectly. You should go through and carefully check your changes.

There is nothing unusual about the MV: CW pin is input signal, CCW is ground and wiper is the output. Just looks a bit weird due to the screened cable.

Oh No! Looks like I attached the wrong schematic, here is the correct one. It's a rotatable PDF:

http://www.prowessamplifiers.com/sch..._ygl3_3a_b.pdf

Someone had changed the two cement 470ohm resistors for 220, I switched them back to scvhematic values. Once I find all the problems I intend to switch them to 330ohm because the owner wants more "balls". I also swapped out the 5k Cement resistor that was badly burnt, checked the leads on these and they match up. "R11" corresponds, to r17 on the correct schematic, a 15k carbon comp that terminates correctly as well. R9 is less translatable as there is some circuitry preceding the MV on the correct schematic. They are all in the correct place leading up to V6. I am going a little crazy rechecking everything....

[nickb]

Oh No! Looks like I attached the wrong schematic, here is the correct one. It's a rotatable PDF:

http://www.prowessamplifiers.com/sch..._ygl3_3a_b.pdf

I hate it when that happens...

The MV is only intended to work on the drive channel 2. I don't think you have a problem

Someone had changed the two cement 470ohm resistors for 220, I switched them back to scvhematic values. Once I find all the problems I intend to switch them to 330ohm because the owner wants more "balls". I also swapped out the 5k Cement resistor that was badly burnt, checked the leads on these and they match up. "R11" corresponds, to r17 on the correct schematic, a 15k carbon comp that terminates correctly as well. R9 is less translatable as there is some circuitry preceding the MV on the correct schematic. They are all in the correct place leading up to V6. I am going a little crazy rechecking everything....

I would make them no lower than 470. The tubes will be less stressed and the hum will be lower. The difference in output power, just a few watts, will be negligible. Remember a 100W amp is only twice as loud as a 10W one. Also one of those 470's is the the screen supply. Go lower and you risk melting the screen. Always choose safety then reliability over power.

[Mr_bibbles]

Jesus!!! The guy I'm fixing it for has been INSISTING that the MV worked on channel one before I had initially changed some things.... I thought I was going insane. Follow up question, if I wanted to tap the first channel into the MV, how would I do it?? Just in case this PITA guy I'm helping out needs a MV on a channel he never uses

For educational / archival purposes, does anyone have a link to a decent explanation about how the MV circuitry works?

Either way I F*****G love you guys, thank you so much for your help.

[mozz]

I see 2 schematics for that model a ygl3 mk3 and a ygl3/3a mk3.

[Mr_bibbles]

This is the correct one:

Prowess Amplifiers

[nickb]

Jesus!!! The guy I'm fixing it for has been INSISTING that the MV worked on channel one before I had initially changed some things.... I thought I was going insane. Follow up question, if I wanted to tap the first channel into the MV, how would I do it?? Just in case this PITA guy I'm helping out needs a MV on a channel he never uses


Either way I F*****G love you guys, thank you so much for your help.

Try this - yell if you don't understand - it's a bit er...rough..

For educational / archival purposes, does anyone have a link to a decent explanation about how the MV circuitry works?

It's a potentiometer - try this explanation
Potentiometers: what they are, how they work and how to use them with Arduino | Varesano.net

[Mr_bibbles]

Try this - yell if you don't understand - it's a bit er...rough..
[ATTACH=CONFIG]41259[/ATTACH]



It's a potentiometer - try this explanation
Potentiometers: what they are, how they work and how to use them with Arduino | Varesano.net

Verrry funny I guess I had always figured there was some sort of input/output buffer circuitry and not just simple voltage division. I'm self taught so a lot of things escape me as I get better. Thanks gentlemen!

[The Dude]

FWIW: Your link in post #10 takes me to a page that says, "I'm sorry. The page you have requested has either moved, or does not exist. Please try again, or contact me if the problem persists."............or is it just me?

Edit: Oh never mind. I see the correct one is in post #6.