Peavey Delta Blues - No Sound - All Tubes Glow - Powered "On", Made a "Hum", and died

[Renegade44]

Ok Guys, I need some help. I have read the forums. Searched for all combinations of "Peavey", "Delta Blues", "No Sound", "Problems", "hum", and even tried the "Classic 30". I may have overlooked the answer but it was not due to a lack of searching.

I have an OLD Delta Blues. It's my main amp. I have a Classic 30 as a backup and stereo sidekick to the DB. I got it new the first year it was produced. I gig with it, usit in the studio, and play it daily. It has been a TRUE work horse. In all the years, it has never let me down. I have never replaced the tubes either. (I know i will catch heat for that from the board. )

I am a fair electronics trouble shooter. I am NOT an engineer or technician.

With all that said, here is my problem.

I turned the amp on last night. As soon as I hit the switch, it started to hum. It was a moderate volume - pitch was maybe an "A". It was not a squeal. It lasted about 5-10 seconds. Then, nothing. No tone, static or hiss. Both channels act the same. Crank normal to 12 - quiet. Crank Pre and Post to 12 at the same time - quiet. All the tubes glow just as they always have. The power light is lit.

This was the first "power on" after getting home from a gig. I did have some effects in front of the amp and in the effects loop. But, that is normal for me.

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I have not tried inserting into the input from the effects loop yet. I just saw that this morning and will give it a try when i get home.

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Blessings,
Stephen H. King
stephen@off61.com

[Garydean]

It's completely quiet? Nothing out of the speaker at all? Check the speaker connections and the speaker with a 9V battery to make sure that works first. You say the tubes are lit. Do you mean the heaters are lit or is the whole tube lit after the standby comes off?

[Renegade44]

I will check with a 9v. My assumption it the speaker will click once. I can also use some alligator clips and drive it from the Classic 30 (after i disconnect the C30 speaker) as another test.

The Delta Blues does not have a "Stand by" just "On". The end of the tube away from the legs glows on every tube. It has 3 - 12AX7 and 4 EL84 tubes.

Blessings,
stephen

[Garydean]

Your tubes are all "lit" which means they are getting AC to the heaters. If the tubes are not fully glowing then they are not getting proper DC, which could be an issue with the power supply, B+.

How comfortable are you about removing the chassis to check fuses and voltages, close to 350vDC in that amp? If you have never done this before I suggest reading about the hazards involved with this procedure, or bring it to a tech.

[pila]

You would need to check for plate voltage on the EL84s. Like mentioned above, the B+ to the plates etc may be down or gone. Depending on the age of the amp, the filter caps may be a problem, like one may be shorted and take out the high voltage in the power supply. There may possibly be a fuse in the power supply (?) Don't know that amp very well. Also it has a solid state rectifier I believe, so some diodes may be a problem.

[tubeswell]

Have you tried a new set of output tubes? (Do the simple stuff first). You're going to need a new quad anyway - Those EL84s should really be changed every 12 months or so if you're using it a lot. (Try using the set from your C30 as a quick-fix)

[Amp Kat]

I think you blew the HT fuse inside the amp. May need to take it out of the cabinet and replace that fuse if it shows open. And btw it was most likely blown from a bad tube !

[pila]

Yes, that sounds like a scenario that would be likely. I've had shorted 6V6s.

[Enzo]

I think AMp Kat is right, a blown fuse, and the most likely reason for that is a bad power tube.

Your Delta Blues is identical to your Classic 30 except for the tiny trem circuit they added. And of course the cab and speakers.

[jmaher1023]

I am having a similar problem with a classic 30. It powers on fine, tubes are glowing, but I only get a minute amount of distorted sound out of it until I turn the power switch off, then I get full sound until the juice runs out! This is not my amp, I am troubleshooting it for a friend, and the way he described it "dying" sounds exactly the same-turned the power on, got a bad hum, then nothing. He also had all the tubes replaced just prior to this happening, and all the fuses look to be good. Any thoughts?
Thanx,
Jim

[Renegade44]

there was a blown fuse. I have not picked up new tubes yet. I'll post the results but i expect everything to run fine. It's a tank!!! I love it!

[Enzo]

Great, let us know.

[Enzo]

Jim, Hi, welcome to the forum.


Please start a new thread for your amp. He had no sound and blown fuses, you have sound. It may be weak or crappy or distorted, but it is sound regardless. SO it is a different problem.

You may have a bad tube, you may have voltage missing from part of the circuit, a leaky cap, hard to say at this point.

[usasdiv]

Jim,
I am having the same problem with my Delta Blues......Please let me know what you find....usasdiv@aol.com.......

[Renegade44]

OK, Sorry not not posting back sooner. My problem was in the diodes on the power section. I replaced the 1N4007 and 1N4003 diodes in the power circuit. Problem solved. I did not bother testing each diode to look for the bad one. I just swapped them all. I also replaced all of the diodes with 1N4007s. It's a little risky in that it will allow more voltage.

Blessings,
stephen

[Enzo]

Not risky, safer. A 1N4007 doesn't "allow" more voltage, it can handle more voltage without burning up. The only job a rectifier has is to let current through one direction and stop it in the reverse direction.