Where would be the best place to insert a reverb circuit into a tweed tremolux 5G9?

[Chuck H]

Ha ha. The blue O just represents that the lead is "encircled". Notice there's one on either end of the dotted blue line. The blue dotted line would be the shield. It's a schematic symbol for a shielded lead.

[Dandrix]

i am replacing my yellow lead with your dotted blue wire(shielded wire) attaching were the the yellow was on the pot? blue (0) on the pot is messing with me. sorry for the confusion

[Chuck H]

Here you go. I made a note on the drawing, but I'll say it again here. Keep the reverb signal leads short. I'd even shorten the jumper on the dual pot. Run the reverb lead from the pot over the board, keep it short and suspended as shown. I know that soldering three leads to that ground lug on the reverb pot is a little bit of a PITA but you'll have to manage. Additions in blue.

[Chuck H]

as for the 100pf cap i will have to order that. i think i only have a 10pf and a silver mica 500pf cap left in the arsenal?

Fender uses a 220p cap. You could series three 500p caps for 166p. A good tweener value. No one looking inside but you

EDIT: About the "sounds a little brighter than i last remembered?"... The mixing stage has a low impedance output. This would make for a little less HF damping at the PI input than the stock amp. It's not so much brighter as more clear. I've found it to be an improvement most often but that can be adjusted too. The upside is that the mixing stage your using has overall MUCH lower distortion than the 3.3M/10p mixer. That thing distorts like crazy. And not the good kind of distotion. More like a phase error that makes the waveform look sorta wonky. The mixer you're using now is the better choice for keeping the amps stock character.

[Dandrix]

Planning to move that lead above board. I'm not sure what you mean by "interconnect cable" but I'll guess it's the same thing the rest of us call shielded cable? I never intended it to travel under the board. That's why it wasn't a dotted line in the layout I constructed. Looking at your actual layout I can see that the lead is longer than what I perceived. So I think a shielded cable, as short as possible and not run under the board would be best. Ground the shield at the reverb level pot ground.

You'll need to add a series resistor to the reverb circuit following the dual pot. On the layout I did I was counting on one of the unused mid board eyelets for this. You've layed things out a little differently, but I can see that you'll know how to manage this. So take the shielded output from the dual reverb level pot to a 220k resistor on the board and then to the mixer stage grid. I also didn't include any top end bleeders to mitigate HF oscillation. Sometimes you can get by without them. Add a 100pf cap from anywhere on the reverb pot that manages signal to the ground on that pot. If I've failed to describe this well enough I'll post a modification to the layout image.

If I've failed to describe this well enough I'll post a modification to the layout image.

yes, that would be totally awesome. so there is no confusion on my part. ty

shielded cable i meant." interconnect" maybe the name of the manufacturer?
as for the 100pf cap i will have to order that. i think i only have a 10pf and a silver mica 500pf cap left in the arsenal?

[Chuck H]

The wire that comes from the node of 510k and 470k (yellow wire in my pictures) to the reverb pot middle lug. did you want me to use interconnect cable for that connection? if i tap it or move it around it makes noise in the circuit.
let me know what you think

Planning to move that lead above board. I'm not sure what you mean by "interconnect cable" but I'll guess it's the same thing the rest of us call shielded cable? I never intended it to travel under the board. That's why it wasn't a dotted line in the layout I constructed. Looking at your actual layout I can see that the lead is longer than what I perceived. So I think a shielded cable, as short as possible and not run under the board would be best. Ground the shield at the reverb level pot ground.

You'll need to add a series resistor to the reverb circuit following the dual pot. On the layout I did I was counting on one of the unused mid board eyelets for this. You've layed things out a little differently, but I can see that you'll know how to manage this. So take the shielded output from the dual reverb level pot to a 220k resistor on the board and then to the mixer stage grid. I also didn't include any top end bleeders to mitigate HF oscillation. Sometimes you can get by without them. Add a 100pf cap from anywhere on the reverb pot that manages signal to the ground on that pot. If I've failed to describe this well enough I'll post a modification to the layout image.

[Dandrix]

Those numbers are good. Noise gone is good. Tell me, does the amp sound pretty much as it did before the reverb was added? I ask because it should sound almost exactly the same so if it doesn't that could be a symptom. The only difference is that your signal is flipped 180 degrees. So there may be some small nuances that will be different if you always sit in the same place WRT the amp.

So the reverb is no longer breaking into static noises? Just oscillation and feedback? Also, do you have ample reverb at 5 before the problem starts. I expected the circuit to have too much reverb when we started this actually. Last question, does the static noise start at the same time as the oscillation or does happen anywhere you rotate the control?

The sound is good, good mix. if i said it sounds a little brighter than i last remembered? would love to hear a real fender 5g9... bucket list.
no static noise, alittle hum. figured it was part of the reverb needing some dialing in? feedback low hum to high pitch squeal (oscillation and feedback?)
plentiful amount of reverb up to five. would be enough
" Last question, does the static noise start at the same time as the oscillation or does happen anywhere you rotate the control?" After 5 on the dial for sure.

Questions for you:

The reverb pot makes a staticy sound as it is raised(wiper noise?)up in level. The wire that comes from the node of 510k and 470k (yellow wire in my pictures) to the reverb pot middle lug. did you want me to use interconnect cable for that connection? if i tap it or move it around it makes noise in the circuit.
let me know what you think

[Chuck H]

Those numbers are good. Noise gone is good. Tell me, does the amp sound pretty much as it did before the reverb was added? I ask because it should sound almost exactly the same so if it doesn't that could be a symptom. The only difference is that your signal is flipped 180 degrees. So there may be some small nuances that will be different if you always sit in the same place WRT the amp.

So the reverb is no longer breaking into static noises? Just oscillation and feedback? Also, do you have ample reverb at 5 before the problem starts. I expected the circuit to have too much reverb when we started this actually. Last question, does the static noise start at the same time as the oscillation or does happen anywhere you rotate the control?

[Dandrix]

Good news!
FIXED the static issue. Yeah!
updated numbers are B1: 394 B2: 391 B3: 347 B4: 330
Driver pin1: 390v 2: 6.2mv 3:7v 6: 388v 7: 6.2mv 8:7v
Recovery Pin1: 221v 2: 0v 3: 1.7v 6: 229v 7: 0v 8:1.7v

Do you think these numbers are GOOD?
so, the reverb will make it to 5 then starts to feedback low to high pitch squeal. the pot makes a staticy sound as it is raised(wiper noise?) in level. The wire that comes from the node of 510k and 470k (yellow wire in my pictures) to the reverb pot middle lug. did you want me to use interconnect cable for that connection? if i tap it or move it around it makes noise in the circuit.
Thanks for the help today with touching up solder joints

[Chuck H]

Could you clarify pin numbers of tank return and of mix triode?

recovery 12ax7: 1:214 2: 0v 3: 1.7v 4/5: 3.3vac 6: 89v 7: 3v 8: 3.7v 9: 3.1vac

I'm only assuming 6, 7 and 8 are the mixer. Regardless, plate 89V, grid 3V and cathode 3.7V ain't right.

[g1]

Strange readings now on the mix triode of the recovery stage. Hrmph. Please remeasure the reverb recovery triode.

Could you clarify pin numbers of tank return and of mix triode?

[Chuck H]

Well do the top stuff first. No sense lifting the board if you don't have to.

[Dandrix]

I have a hunch there's a cold solder joint or joints. You can try touching up any iffy looking joints. If it's not full, smooth and shiny with obvious wicking onto the components leads then it's suspect. Anything with gaps, graininess or showing surface tension on the component leads or eyelets should be reheated and add a dot of your flux core solder. But don't overload the eyelets to where they drop a solder puck out the bottom. It's also possible the problem is UNDER the board. Oh I know how great that is once you've put everything in place.

will do. the under the board thing

[Chuck H]

I have a hunch there's a cold solder joint or joints. You can try touching up any iffy looking joints. If it's not full, smooth and shiny with obvious wicking onto the components leads then it's suspect. Anything with gaps, graininess or showing surface tension on the component leads or eyelets should be reheated and add a dot of your flux core solder. But don't overload the eyelets to where they drop a solder puck out the bottom. It's also possible the problem is UNDER the board. Oh I know how great that is once you've put everything in place.

[Dandrix]

Same voltages, a lot of noise