Peavey 5150 II no sound. SEARCHED ALL OVER! PLEASE HELP!

[drumguy560]

Hi all, long time lurker, first time poster.

Here's the situation...

5150 II powers up, all tubes glow, channel switching works fine.

I get no sound out of the amp, the power tube board to main board ribbon cable and connections has already been replaced / cleaned up. (that was its first problem). Screen grid resistors have all been replaced with higher wattage tolerance resistors.

Here's the weird part...The amp turns on, comes off of standby, but when i turn up the pre and post gain (on either channel) the tubes glow bright blue, not "i'm going to explode blue" but the "blueness" grows in intensity relative to the gain controls increase. When i strum a note on the guitar, i see bursts of brighter blue light, but i get no output from the amp. I had a marshall jcm900 one time that the speaker transformer went out on, that made a noise that a very quiet spring being "sprung" when playing notes. This amp makes the same extremely quiet noise.

I am an electronics tech by trade, but my hands do shake a little (thanks genetics!) so working on the amp whilst powered on kinda scares me...not to say I'm not willing to do it...but ya know...

So any ideas anyone?

Thanks in advance to this great forum!

[Enzo]

QUIT PLAYING IT!!! Your description is of an amp that is working but not conected to a speaker. This can destroy an amp. If the problem is zero sound coming out, then just restoring some "background sound" should be enough to tell you it will work again. ONLY after we get some sort of sound, THEN play.

First, test your speaker cord between some other amp and speaker. And make sure you are using an actual speaker cord and not just a guitar cord. Play some other amp through your speaker. Do the cord and speaker work? No cheating. Can't say, "I know this is OK, it's new." Nor "It worked yesterday, it must be still OK."

Are you using the 8 ohm or 4 ohm output jack? Try the other one. It won;t matter if it is the "wrong" one. Does the other work? Or does this one have the switch? If so, run the switch back and forth a few times then try each position.

[soundguruman]

Hi all, long time lurker, first time poster.

Here's the situation...

5150 II powers up, all tubes glow, channel switching works fine.

I get no sound out of the amp, the power tube board to main board ribbon cable and connections has already been replaced / cleaned up. (that was its first problem). Screen grid resistors have all been replaced with higher wattage tolerance resistors.

Here's the weird part...The amp turns on, comes off of standby, but when i turn up the pre and post gain (on either channel) the tubes glow bright blue, not "i'm going to explode blue" but the "blueness" grows in intensity relative to the gain controls increase. When i strum a note on the guitar, i see bursts of brighter blue light, but i get no output from the amp. I had a marshall jcm900 one time that the speaker transformer went out on, that made a noise that a very quiet spring being "sprung" when playing notes. This amp makes the same extremely quiet noise.

I am an electronics tech by trade, but my hands do shake a little (thanks genetics!) so working on the amp whilst powered on kinda scares me...not to say I'm not willing to do it...but ya know...

So any ideas anyone?

Thanks in advance to this great forum!

The tubes glowing blue is normal.
You may have a bad speaker cable
your speaker may be bad
The ohms select switch may be bad...try switching it to another setting temporarily...
check all those things and find the problem before you play it again.
Verify that the speakers are functioning, wired correctly, test the speaker with a 9 volt battery and make sure it POPS and MOVES
when you touch the battery to the speaker terminals.
Plug a speaker cable in, just to the speaker, again use the 9 volt battery at the end of the speaker cable, to verify that the speaker POPS and moves.
Check the speaker cabinet jack for broken connections, etc...look inside and verify that the wiring is connected correctly, and intact.
Remove each speaker, verify that each speaker moves in / out freely, without scraping, and that the coil has continuity.
Check the speaker cable plugs for bad connections, loose parts...
If you play with a bad speaker connection, it can blow the amp up. The amp must have a speaker or load resistor connected. It can cause arcing in the output, or fry the OT...do not attempt to operate the amp without a load connected.
Make sure that the correct impedance speaker is used, and don't try to substitute the wrong impedance.

peavey 5150 - 6505 head.pdf
peavey_evh5150 schem.pdf
peavey-vh-5150-combo-amp-schematic-diagram.pdf

Another thing is effects send and return jacks.
try plugging in a guitar cable between send and return jacks...

[Billy R aka DynaFreak]

good advice re the ohms switch and associated connectors btwn the output stage and speaker jacks. I had a 5150 with similar problem in which there was intermittent contact within one of the molex connectors (factory problem). Had to disassemble the molex and redo the joints. the problem was NOT visible from the outside.

[soundguruman]

good advice re the ohms switch and associated connectors btwn the output stage and speaker jacks. I had a 5150 with similar problem in which there was intermittent contact within one of the molex connectors (factory problem). Had to disassemble the molex and redo the joints. the problem was NOT visible from the outside.

One of my customers had the output tubes turning red.
Turned out to be a worn out plug on the speaker cable.
It just wasn't making a good contact anymore.
And that little plug will kill the amp when it goes bad.
So, the speaker and speaker cable are super important to keep the amp running.

[drumguy560]

Alright. Sorry for the long time away from this problem thread. Let me say thanks for all of your input. The amp was in fact working, it was the cab that was the issue with it making no sound. IT IS NOW MAKING SOUND. However, it is not the correct sound. I have enclosed a video of the strange sound the amp is making. I am comfortable soldering and working around high voltages. I just need to know what to replace. None of the caps have any swelling, not to say they are good...

anyhow, here is the video

Thanks!

Strange Problem With Peavey 5150 II - YouTube

[soundguruman]

Alright. Sorry for the long time away from this problem thread. Let me say thanks for all of your input. The amp was in fact working, it was the cab that was the issue with it making no sound. IT IS NOW MAKING SOUND. However, it is not the correct sound. I have enclosed a video of the strange sound the amp is making. I am comfortable soldering and working around high voltages. I just need to know what to replace. None of the caps have any swelling, not to say they are good...

anyhow, here is the video

Thanks!

Strange Problem With Peavey 5150 II - YouTube

The tubes glow brighter blue with no input:
That's normal. Nothing Wrong.

[drumguy560]

The tubes glow brighter blue with no input:
That's normal. Nothing Wrong.

I figured as much. But did you hear the horrible distorting?

[Gtr_tech]

Oh man.....sounds like arcing to me. Check the power tube sockets (and the board they're mounted to) for carbon tracks. Other than that....I think you may have damaged the output transformer. They can develop partial shorts that won't affect it at a low volume but when you reach a certain voltage at the primary, the arcing starts.

This could very well be an expensive lesson. I hope you learned something from this....

[drumguy560]

Oh man.....sounds like arcing to me. Check the power tube sockets (and the board they're mounted to) for carbon tracks. Other than that....I think you may have damaged the output transformer. They can develop partial shorts that won't affect it at a low volume but when you reach a certain voltage at the primary, the arcing starts.

This could very well be an expensive lesson. I hope you learned something from this....

There are no carbon traces on the tube sockets. I re soldered all of the connections there. Is there a way I can test the output trans with a meter?

[Gtr_tech]

A meter won't find a "soft" short. You need to do a kickback test to check the winding properly.

The Super-Secret Transformer Tester - Premier Guitar