ps cap question

[rutledj]

Is it normal for the 1st stage caps (100uf 300v in series) to get warm to the touch?

I'm trying to trace a hum problem. When I first turn the amp on I get a bunch of popping sounds. Not one after another but here and there. They go away after a couple of minutes.

If I ground out the output of v2 the hum decreases noticably. Probably to just the xfrmr coupling hum. Guitar sounds fine through the channel.

Also, my first clean stage is basically a Fender clean ckt. Haven't gotten to the dumble clean or overdrive yet. Just trying to get the hum out before I switch those in.

Rut

[rutledj]

A couple of grounding questions also. Using Funk's board, I have Gnd connections for B+1, B+2, B+3,4,5 (3 grnd points).

Is this wiring correct:

B+1 ground to the 6l6 cathodes
B+2 gound to ?
B+345 ground to the ground buss running along back of the pots. This is also where I have the preamp cathode grnds connected.

SHouldn't one of these be tied to chassis ground along with the hv center tap?

Rut

[novosibir]

That the first filter caps become a bit warm in use is quite normal! They have the most work with straighten out the remaining ripple from the rectifier.

As for your random popping within the first few minutes - try another preamp tube in V1, what might solve your probs!

Larry

['67_Plexi]

Is it normal for the 1st stage caps (100uf 300v in series) to get warm to the touch?

I'm trying to trace a hum problem. When I first turn the amp on I get a bunch of popping sounds. Not one after another but here and there. They go away after a couple of minutes.

If I ground out the output of v2 the hum decreases noticably. Probably to just the xfrmr coupling hum. Guitar sounds fine through the channel.

Also, my first clean stage is basically a Fender clean ckt. Haven't gotten to the dumble clean or overdrive yet. Just trying to get the hum out before I switch those in.

Rut

NO !!!

They absolutely should not get warm. Are you sure it isn't just transferred heat from elswhere ? However, maybe this symptom and the hum are related. Have you check for good tight grounds from the PS and smoothing caps ?

Transformer coupling hum can be heard with the standby off. It is often induced from the high current filament windings of the PT into the primary winding of the OT. So if you cannot hear it with the amp on standby, move on.
If you do hear it, loosen the bolts on one transformer and just move it a couple of degrees. Small increments can have a huge effect.

I have had experience with JJ power tubes exhibiting the popping symptoms you describe. It clears up after a few minutes. I stopped using them.

Alan.