Amp repair where do I start

[LoveChet]

[LoveChet]

The vibrato channel 1 V2-2 plate signal goes thru a 100k and them from there it goes thru both of those large green caps to the bass pot. Havnt drawn bass pot yet. Also that same plate signal has a 22 Meg to ground AND it also goes thru a small cap. (prob 250 pf) and then from tthat cap on to the 6 position fat switch mod. The vibrato channel 2 input has been eliminated and used to hold the 6 position fat switch. It appears that the standard AB868 circuitry around that channel 1 v2'2 has been totally changed. The AB868 circuit has two caps, two resistors, and a pot all of which is replaced by what I just explained. I havnt yet drawn the channel 1 v2-1 side of that section. I have changed out v2 to be 12AY7 instead of 12AX7 for lower gain as suggested by tone guys (Chet etc)

[LoveChet]

BTW this amp as it is wired now when working was awesome and I could get close to Chets recording quality sound. I had a Big Sky reverb unit in the FX loop followed by a 32 channel EQ. Up front I had no effects other than an Electro Harmonics Signal Pad so that I could max out the guitar pot volume (best tone) and then use Signal Pad to lower volume before going into vibrato channel 1. BTW the normal channel inputs are not used and v1 has been pulled. I also pulled v3 reverb because I use FX loop reverb instead

[LoveChet]

Im continuing on drawing the tremolo input preamp v2 section. I see now that the mods totally change the design of the bass, treble, volume circuit which is between each half of V2 with the 6 position fat switch in there somewhere.

[LoveChet]

BTW when it fell over it still worked but sounded crappy. Now 8 years later it doesn't work at all. I checked spkr recently with ohmeter and it measures around 8 and crackles.

[mozz]

Measuring the speaker doesn't tell you if it is bad. If it fell over and shifted the magnet, the ohms would still be the same if the voice coil didn't open. Put another amp/radio into that speaker and make sure it works properly.

[LoveChet]

Your right on the spkr. It makes sense that if it sounded crappy after it fell over it could well be the problem. Thanks.

[LoveChet]

Making progress on amp wiring schematic with mods. Left to do are Tremolo, phase inverter, 6v6 push pull.
I do have B+ 160v v2 plate, 240v mstr volume plate (1/2 v5 tremolo repurposed for mstr vol, I had missed a resistor supplying B+). I do see that the intensity knob is push pull so i need to consider that when i draw tremolo circuit. Spkr is in correct jack but i need to attach it to another amp to make sure it's working properly as just a 8 ohm test isn't good enough. The two large blue caps I mentioned that were glued together are the .1 and .01 associated with the Bass pot. Not sure if stock but the basic Deluxe schematic has two caps going to bass pot. More to come. All future posts will be on this thread. Thanks !

[LoveChet]

Question on TR4 associated with V3A V3B reverb, the reverb pan and how it might have some relationship to the tremolo mod that my deluxe has. A schematic of my tremolo circuit as modified will follow soon and it only uses one side of V5. The red wire from TR4 goes thru a cap and resistor to the plate of the side of V5 that is the remaining side of V5;tremolo function. ( the other side if V5 is repurposed for the master volume. As far as the black, green, and blue wires from TR4 i assume they are stock but since I have limited knowledge of the reverb circuit component visuals I can't draw what I would call a current full mod of the reverb circuit. I do see that black and green go to the reverb tank and the blue goes to v3 pin 6 plate. My general unerstanding of the tremolo mod is that because of the redesign it no longer needs to communicate with v4 mix.

[g1]

I think you are missing out on a supply connection again. You should find that the red wire at TR4 is going to a supply node. The resistor to V5 plate is also coming off that supply node but is not part of the same circuit.
Assume the basic stock SF circuit with some changes. It might help to be drawing in the mods over top the closest schematic (attached).

[Tom Phillips]

... It might help to be drawing in the mods over top the closest schematic (attached).

Good approach. However, I seem to remember that one of the previous threads indicated that the pull boost on the subject amp was an add on Mod with an extra hole drilled through the amp name on the front panel.
Is that correct LoveChet?

[g1]

I seem to remember that one of the previous threads indicated that the pull boost on the subject amp was an add on Mod with an extra hole drilled through the amp name on the front panel.

I hope he will confirm, if memory serves the extra hole was drilled for a master. The SF Deluxe had the pull-boost on the ch.2 vol. contol.

[LoveChet]

You people are great and way over my head. Yes it has a new hole in front for master volume. And it does have a volume push pull which I have incorporate into correct spot on new master volume circuit. And like I said one side of V5 tremolo circuit was repurposed for master volume.

[Tom Phillips]

... one side of V5 tremolo circuit was repurposed for master volume.

Just to let you know, the usual Fender Master volume is a passive circuit that does not need to use a tube stage. The repurposed V5 triode section is most likely being used as the gain stage for the pull boost circuit.

[LoveChet]

So, now I want to complete a full wiring diagram before I start debugging why amp isn't functioning. I need to draw out the V5 tremolo/6v6 bias, V6 Pi and finally 6V6 push pull output. My basic is question is in tremolo LFO functionality just for knowkedge and how it operates in the stock Deluxe Reverb and how it operates in my modded Deluxe. In stock version both sides of V5 provide tremolo with a feed into V4 mix with the 6v6 bias pot connected directly to 6V6 grids resistors. In my mod, half of v5 was repurposed for master volume but the other half of v5 still has the stuff that feeds the speed pot etc. However in my mod there is no feed from V5 into the mix circuit AND the 6V6 bias voltage now goes through the bias pot AND the wiper of the intensity pot before going to 6V6 grid resistors. Im assuming that the tremolo and associated LFO stuff operates in two totally different ways here but I really don't know theory wise how the stock version and my mod version accomplishes the tremolo sound other than in both cases a low frequency oscillation causes a volume change in the overall 6V6 output