fender blues deluxe reissue no reverb

[pontiacpete]

Hi,
I have this amp in for a couple things, one there was no sound and the amp in and out jack's threaded shafts had been broken off.
The no sound issue was straight forward, a shattered V1. Replaced the 2 in and out jacks.
Now I;m finding that the reverb isn't working, and I can't help but think it's something that I'm may have done.
This particular amp has been repaired a bunch of times. So much so that the main board flops out and is pretty loose compared
to other amps of the kind. So as a result after finishing the jacks I find that 2 of the ribbon cable are having some serious problems
so I cut them out and wire them up with individual wires.
Anyway, I've checked quite a few things here and swapped out components to no avail, no reverb.
Parts swapped Q2 and U2 and the tank. The cables are good, they have continuity to the tank in the right ways, I believe.
Now I need some help.
Could changing the power amp in jack have any effect on the reverb working or not?
Any suggestions on where to proceed?
thanks
pete

[52 Bill]

Could changing the power amp in jack have any effect on the reverb working or not?

The output of the reverb return circuit is sent to the power amp via one of the ribbon cables, the one closest to the driver tube. Did you replace this one?

[pontiacpete]

From left to right I changed the second and third ribbon cable.

[Enzo]

Um, we don't have the amp to look at. Schematically, did you replace the one that carries the reverb out?


The essence of troubleshooting is to isolate the problem. So isolate the problem.

The reverb doesn't work. The reverb is two parts: the drive and the return. pull the plugs out of the reverb pan, and with the amp running and the reverb up some, touch the tip of each reverb cable with a finger, one at a time. In a working amp, one will make a hum when touched. That is the return cable and needs to be plugged into the OUTPUT jack on the reverb pan. If neither hums, then we have a return issue. If one does hum, then the problem is on the drive side. Play something steady, like asignal generator or a CD player or something, plugged into the input jack up front. Now follow the signal through the drive circuit.

[pontiacpete]

There is a hum on the tip of the return cable. I will try and trace the drive side. thanks

[pontiacpete]

One question before I go any further.
Would this type of jack on the 'power amp in' have an effect on the reverb working or not?
This one has the metal sleeve on the inside.

[pontiacpete]

Decided to go ahead and trace the signal.
There's signal on pin 3 of U3 ., nothing on pin 1.

Does this mean I can rule out the power amp in jack I put in?

[pontiacpete]

Now I don't have the +/-16, could have swore they were before.

[52 Bill]

Does this mean I can rule out the power amp in jack I put in?

All of the 9 pin jacks are the same electrically speaking, some have the metal insert and some don't. Unless you tore up the pc board when you removed or installed the jacks, there should not be any reason to suspect the jack.

The missing signal and voltages are much more important clues.

[pontiacpete]

I have 8.4 +/- vdc only.
There is +/-46 on the high side of the big 470ohm resistors, (this on has the 470r s not the 330r s).
Something is pulling down on both sides equally,

[52 Bill]

Is the soldering good on the two 470 ohm resistors? Any dc voltage on in/out pins of the two ICs?

[pontiacpete]

no dc on in/out pins.
470 ohm resistors are connected, but will check

[Enzo]

The power amp jack is not related to the reverb. The metal ring at the mouth of the jack is a trim piece.

Your 15v supplies are loading down the same, so likely something loading between them. My first suspect is an IC, are any of them getting hot to the touch?

[pontiacpete]

The IC are not getting hot.
I did find one mistake in my reporting, there's voltage on pin2 of U2. It has -5.1vdc. Better just list all voltages,
pin 1 -1.2vdc
pin 2 -5.1
pin 3 0
pin 4 -7.0
pin 5 7.0
pin 6 0
pin 7 0
pin 8 0

U4

pin 1 -5.7
pin 2 .4
pin3 -.7
pin 4 -7
pin 5 7
pin 6 6.8
pin 7 0
pin 8 6.8

U3

pin 1 -5.7
pin 2 -1.1
pin 3 0
pin 4 -7
pin 5 7
pin 6 -5.3
pin 7 3.1
pin 8 .9

U1

pin 1 0
pin 2 0
pin 3 0
pin 4 -7
pin 5 7
pin 6 0
pin 7 0
pin 8 0

nothing happening on U1 ....

[52 Bill]

I think that you have the pin numbers wrong in your lists. The pins are numbered in a counterclockwise order 1-2-3-4 and then 5 is the lower right hand pin. So what you are calling pin 5 is actually pin 8. The negative supply voltage should be on pin 4 and the positive supply on pin 8.

U1 is the FX loop buffer, U2 is the reverb driver/return amp and U3 and U4 are the channel switching chips. So there should be voltages on most of the pins of U3 and U4. But there should be no voltage on the in and outs of U2.

Try replacing U2.