Fender Hot Rod Deluxe Noise

[misterc57]

I just tuned up this HRD. Checked all HV, all tube pins at the board look good. I saw a slight burn area at the power resistor of V4 but HV is there on the tube pin. Someone had replaced the OT.

Everything seemed good. Played well on the bench but I did not play for very long.

Buttoned it all up, played for a few minutes and then the noise started (lots of crackling sounds). Turned all volumes to zero, still noise. Disconnected the guitar cable, still noise.

I believe these are known for having issues.

I will open it up again very soon and start to chopstick, etc.

Thought I would check in for any suggestions.

Thank you, MarkO

Attached schematic I am using.

Fender-Hot-Rod-Deluxe-Schematic.pdf

[Jon Snell]

Does any of the controls ; Vol, Tone etc, have any effect?
That would narrow it down a fair bit.

[g1]

Not sure how old this one is, but lead-free solder doesn't always show visibly when it's bad. And solder joints on the tube sockets are very often a problem with these models.
Phase splitter plate resistors are also a common fault.

[misterc57]

V3 phase splitter plate resistors are at spec.

When the problem was happening the vol pots had no effect. I have not been able to get it to happen again.

I played the amp for about 15 minutes, tried chopsticks, smacking the cab, etc....

I know this noise will come back at some point.

[mozz]

Phase splitter plate resistors are also a common fault.

Change all the plate resistors. You could try tapping on them when running but I don't know if that will show any signs. Give it a few minutes to warm up.

[Mick Bailey]

As per g1's suggestion - tube socket solder joint cracks around the pins is the No.1 cause of crackling in these amps. I always eliminate that first as a possibility and resolder every joint. Tube problems are another cause possibility - a charred screen resistor may be historic, but could also point to V4 breaking down.

[misterc57]

Thank you all for the suggestions. The owner does not want to put any more repair work into this amp.

[misterc57]

As I was putting the amp back together and playing it a bit the noise started again. If I moved V5 the noise would come and go. I reflowed the output tubes. No noise now, hopefully that was it.