Can someone tell me what this mess is?

[bigdrums925]

So a client brings in a Fender Hotrod Deluxe saying that occasionally when switching from clean channel to the drive channel using the foot switch, the amp would suddenly be in the drive channel but full on volume when the gain and master volumes were turned down low.
We tested it when he got it here and foot switch doesn't change the channels at all even though the lights on the footswitch go on and off as expected. The drive channel light on the amp stays on regardless, and the amp stays in the clean channel all the time. Sound is normal in the clean channel.

So I open up the back of the amp and right off I see the mess shown above. First I suspected the 22uf 500v cap to be leaking down on to the 2 resistors 470 ohm. There is remnant's of whatever is causing this (most visible on the resistors) also on the board and down below the resistors on the lower board that holds the tubes. I checked the 22uf 500v cap and it checks normal. Also checked the resistors and they both measure near 470 ohms.

Any ideas here?

[drewl]

Well those caps are definitely leaking but I don't think that's the source of the red goop.

Maybe some type of epoxy to hold them in place, or someone bled all over them?
Spilled Red Bull?

[Jazz P Bass]

Not too sure what the 'mess' is.
Cap guts.
Previous attempt to 'reglue' the 5 watt resistors.

Besides the mess, do you have the voltage drop across the two power resistors.
End result should be +16Vdc & -16Vdc.
Ft Sw will not work unless both are present.

[mozz]

^^^^ beat me to it.............Was worked on before. Those resistors are known to cause channel switching problems, i have one on the bench now. Well, the solder and traces going to those resistors are the problem because of heat. Somebody used epoxy or whatever that is to hold them steady. Next one i get i am mounting heat sink resistors to the chassis and running wires.

[mikepukmel]

If the caps aren't leaking, maybe its cherry coke?

[Enzo]

Caps don't leak red goo, that looks like glue to me. It keeps them from shaking around. If you have +15 and -15, the resistors are working.

The 500v caps look spoogey to me too, but they have zero to do with channel switching.

Unplug the footswitch, does the amp change channels and drive normally with the panel switches?

Is the footswitch the official real fender one for this model? The schematic has a series of test points and notes about then on the left margin, use them.

[Mick Bailey]

Those caps certainly need replacing. Even when they don't show a crusty mess they're almost always bad and if one is leaking all the rest will be close behind. Those Illinois caps are pretty crap. That's aftermarket glue on those resistors - I've seen this on quite a few amps.

[stokes]

I'm with Mick on those Illinois caps.I've seen far too many of the newer Fender amps using these caps with various symptoms being caused by these caps.Dont think it has anything to do with your switching problems,but I would replace them.Like I've said,most problems I've seen with these Deluxes,Devilles,Blues Jrs and reissue Fenders are related to those Illinois.I've even replaced them for friends that had no symptoms and the improvement in the amps performance was remarkable.

[Sowhat]

That red stuff is glue. R78 and 79 have been known to get cracked solders or cold solders or whatnot, the point is that, aside from re-soldering these connections, some tech's like to add a little insurance in the form of some glue to hold them steady under vibration.

That glue probably did not start out being red, it was probably yellow or beige and those resistors get hot in normal operation so the glue has gone through some thermally accelerated chemical transformation over time winding up as a crusty red residue... like any good pizza!

[bigdrums925]

Due to the unending support here I always want to express my gratitude by at least following up.
The problem was bad solder on R78 & 79.
It's working well now but have noted that the Illinois caps are not the best and will keep that in mind.
Thanks to all once again. One day I will have all these projects cleared out. Looking forward to that!