Peavey Encore 65 blows fuse

[hypnostuff]

I'm having an issue with this amp blowing fuses with known good tubes. Can't see any fried components. Can play the amp for about 30 minutes and the 3 amp fuse blows, from the schematic this looks like the heater protection fuse. My question is, does this model of amp have a known history of manufacturing mistakes that just makes it blow fuses? LOL

[J M Fahey]

a known history of manufacturing mistakes that just makes it blow fuses?

No.
Life is not *that* simple.
Any such mistake would have been caught in the cradle by Peavey R&D team.
Unfortunately, you will have to troubleshoot.
Start by posting or linking to its schematic so we all talk about the same.
Good luck.

[Jazz P Bass]

I'm having an issue with this amp blowing fuses with known good tubes. Can't see any fried components. Can play the amp for about 30 minutes and the 3 amp fuse blows, from the schematic this looks like the heater protection fuse. My question is, does this model of amp have a known history of manufacturing mistakes that just makes it blow fuses? LOL

How did we come to the conclusion that the tubes are "known good"?
The heater circuit blowing the fuse usually means a bad power tube.

[hypnostuff]

Thanks for pruning the duplicate entry.

I'm assuming that the shop that I just got the amp back from checked the power tube, because they found a bad preamp tube at V2 during their diagnosis.

The amp will play fine for about 30 minutes at loud volumes, and for much longer than that at low volumes. It will idle indefinitely. It sounds great when it's working.

This is the third time I've blown the 3A. Same symptoms every time. I think probably the amp is ruining the tubes, not vice-versa.

I've noticed that a couple of the resistors are seemingly malformed. They don't have the "sausage" shape of a normal resistor, they are somewhat spherical in shape. Are they melted? There's no evidence of burning. I will send pics and indicate which resistors they are in the schematic.

Thanks!

[52 Bill]

Exactly which fuse are you talking about? F4 the filament fuse is listed as 6 amp. F5 the main ac fuse is listed as 3 amps.

What type of fuse are you using fast or slow blow?

[hypnostuff]

It's F5 - using a slow blow. This is what happened the 1st and 2nd time that it stopped working. I'm going to unbutton it tonight and see if it's the same one.

[hypnostuff]

f5 is blown...




in the wide shot, does anyone thing the gunk around the tube sockets is bad looking, like melted flux?





Possibly smoked resistor...R53, seems to go to v4b plate...




in the pic above, you can see the "malformed" resistor that I was talking about. guess what, it's a cap. duh!!!!!


Thanks....

[Jazz P Bass]

Change out the output tubes.

[hypnostuff]

Took the amp back and tested the output tubes. One was "on the low side of marginal" on an old tymey "test it yourself" rig. Replaced the fuse, Swapped in a set of 6L6CG from an old amp I used to own (after testing them both). Ran the output through an amperage meter on "11" for about an hour, output going into a speaker. Ran like a champ with no AC ripple for about an hour, dimed out. The Ruby 6L6GCMSTR tubes were the culprit.

Thanks for not suggesting a million different things to check out. Now I know to check for bad output tubes first when an amp is blowing fuses.

Now to play some loud guitar and see if anything else goes wrong!

Thanks!