Brownface Potentiometers

[martin manning]

Might be the socket, then?

[strat100]

Had a probe around v6 and changed the tube and now got correct voltages and we now have sound again but its sounds like its ring modulated but wow it thumps with the vibrato. Now to find out whats wrong with the signal and where. i havnt got an oscilloscope but i am wondering if i will need one.

[strat100]

Just noticed i have vibrato on both channels and footswitch is not turning it off what have i done now

[strat100]

Got 318v dc from the end of the 0.05 uf cap attaching to point X on the schematic so that needs replacing and its a brand new cap too.

[sluckey]

Got 318v dc from the end of the 0.05 uf cap attaching to point X on the schematic so that needs replacing and its a brand new cap too.

That's normal. The voltage is coming from the tremolo modulator circuit. Look at the schematic.

[strat100]

Realised that now thank you what i should have said is i have dc on pin v6 pin 2 and if i touch the junction of 2 x 470k and 220k it crackles really bad along that section. took the board off to double check the wires underneath and they are all where they shoud be so that leaves a dodgy 0.001uf cap and guess the only cap a havnt got in my stash so will have to order.

[sluckey]

what i should have said is i have dc on pin v6 pin 2...

That's perfectly OK too. V6 is a LTP PI and the grids will have a positive voltage on them. LOOK AT THE SCHEMATIC. It shows that there should be about 30V on pin 2. Nothing wrong with that .001µF cap.

It's OK to have dc voltage on a grid. All depends on the circuit.

[strat100]

Thanks for your patience it takes longer when you get to my age so i got something else going on then and i struggle to interpret schematics but trying to get my head round why that junction is so sensitive and i got vibrato on both channels and the ring modulation distortion, it all points to that spot but cant seem to find anything wrong or most importantly WHY, have changed tubes checked wiring underneath all voltages are more or less spot on to the schematic. Probably need to step back and relax and leave it for a few days. Could take it to my nearby tech but i want to learn Why this is happening and what am i missing.

[strat100]

Checked wiring again, checked i rewired the vibrato to Martins schematic and everything is as should be but still get vibrato on both channels and ring distortion and cant manage to turn off the vibrato with the footswitch(works with my 6g3). Is it normal to hear the vibrato through the speakers with guitar plugged in but not playing?
Its very loud its like a squeek squeek and if i turn speed up it goes crazy thumping and squeeking.

[sluckey]

cant manage to turn off the vibrato with the footswitch(works with my 6g3).

Looks like you used isolation bushings on the vibrato footswitch jack. Either remove the bushings so the jack metal body contacts the metal chassis or connect a ground wire to the ground lug.

[strat100]

Looks like you used isolation bushings

Worrying to much about everything else.

[strat100]

Please bear me with but have learned hell of a lot last couple of days and have chucked the layout and trying to learn the schematic and its hard to learn new stuff at 60+ years.
No oscilloscope but have a audio generator so made a probe to trace the signal,.....
Signal into Vibrato channel and traced it through to the amp and found that i also found the signal on channel one and with a dummy load on i could hear the amp noisily vibrating with the vibrato. the signal is going through the amp but cant find the spot its joining channel one, so its obvious that i am at the limit of how i can interpret this knowledge but the amp vibrating with a dummy load has thrown me.
Signal in channel one and it doesnt mix with channel 2
Any help would be gratefully received.

[strat100]

Just found out that on 6g amps the normal channel is louder than the vibrato channel on mine its the other way round.

[sluckey]

the signal is going through the amp but cant find the spot its joining channel one

The junction of 2 x 470k and 220k is the spot where the normal channel joins the vibrato channel. You were all over it yesterday.

Turn the vibrato off with the footswitch. That should work if you did what I suggested earlier today.

[strat100]

Got the footswitch sorted thank you........ signal in normal channel and the signal is on all 3 resistors straight tone on 220k and vibrato on both 470k. and the amp is vibrating with vibrato '
Sgnal into Vibrato channel all 3 resistors have vibrato on them and amp vibrate with vibrato.