Peavey Delta Blues 115 No Sound

[strokerrace]

I recently went to play my Delta Blues amp, turned it on, waited for tubes to warm up, and then tried to play some. There wasn't the usual hum and no sound at all came from the amplifier. I looked at the tubes on the back and the 3 pre-amp tubes were lit, but the power tubes were all dark. I figured it must be time for some new tubes, so I ordered the JJ Blues Low Output tube set from Eurotubes. While I waited for the tubes to arrive, I pulled the chassis and checked the fuses and gave everything a look over. I replaced all 3 fuses, checked the resistance of the speaker, and did not see any obvious failures on the circuit board.

Fast forward to yesterday, I received the new tubes, installed them, powered it up and no sounds still. The only difference is one of the power tubes (the one farthest from the pre-amp tubes) was lit up now, along with all 3 pre-amp tubes as they were before. I'm stumped. I don't really have any experience with tube amps, so I'm not sure where to start looking.

Any help appreciated.

[Pedro Vecino]

Even with a single EL84 it should sound somehow. The amplifier may have problems with the tube sockets contacts.
Connect a guitar cable between send and return to see if it recovers the sound.

[Enzo]

Actually, the heaters in teh four power tubes are wired in series - so either they all light or none. I can't see hopw a single tube would light.

[strokerrace]

I'll check it when I get home today and report back.

I have a pic of it with the one tube lit, not sure how to upload it though. I thought it odd too. Even turned the lights off to see if the others were dim.

[strokerrace]

So I tried the cable from the send to return with no luck. I also moved the one glowing el84 to another socket to see if that changed anything. When I moved it to another position, it lit up again but the other 3 power tubes were still dark...

[strokerrace]

Fixed! Jumper JP518 was broken in the middle of the wire. Got the flashlight out and inspected the board closer, found the break, soldered it back up and tested it. All tubes lit and sound again!

Thanks everyone for the help!

[xtian]

Glad you got it fixed! But the thought of a jumper wire breaking in the middle has my brain spinning! Any idea how/why?

[Enzo]

The little solid sire jumpers are subject to vibration between the two boards. They break. This is not a jumper wire on a board, this is from one board to another.

[Randall]

Those jumper wires are pure evil in those amps.

[g1]

So how can that broken jumper make one tube light and 3 not if all 4 are in series?

strokerrace , are all 4 looking same brightness now?

[Enzo]

Without resulting in 24v across one tube, it baffles me...

[Jazz P Bass]

I have a pic of it with the one tube lit, not sure how to upload it though.

On the right of a Reply are three icons.
The furthest to the left is the icon for 'attaching' files & pics.

[strokerrace]

Enzo is correct, it was going from one pcb to another, not a wire on the pcb itself.

All tubes are the same brightness now. I suppose it shorted and gave the one tube 24V? Not sure but the one that lit up was more of a brighter/whiter light than the typical orange glow in the tubes.

It is still odd, but I'm not going to investigate further into the circuitry since its working now lol.

Jazz P Bass, it says I am not authorized to create or remove attachments when I try to post the uploaded image, not sure why maybe because I'm still new here...

[Enzo]

You only have five posts, it will settle out soon for you. There are PLENTY of spam bots cruising the web, and without these rules we would be swamped with SPAM. Once they know you are a real person and a participant, the rules will accept you.