Peavey Vypyr 120 Tube

[steelguy]

Anyone have a schematic? HV power supply blowing fuse.
Thanks in advance.

[Enzo]

Probably a bad tube.

COntact customer service at Peavey and ask for the schematics.

[mozwell]

It may be similar to the 60W version, just using 2 extra power tubes & a different output transformer.
There are several fuses on the 60W version, does your amp have these too ?
Which one is blowing ?

Pull the output tubes, does the fuse still blow ?
As Enzo said, likely a bad tube

[xtian]

120 watt head on bench. Has buzzy noise even when on standby, even with all tubes pulled. I observed 350-400 vDC at the OT CT (varying with time, up down up down), BUT ALSO observed 120 vAC at same point! Wall voltage is slipping thru the rectifier, right? So I replaced the four 1N4007s in the rectifier--no change.

How else can the 120 vAC be getting to the OT?
VYPYR 120 watt.pdf

[xtian]

Further info: I disconnected ALL the PT secondaries except the HT (two red) wires. STILL see 120vAC at B+. WTH?

BTW, amp works fine, all functions, except for bad noise at speaker output. Noise is not in preamp--headphone out sounds fine.

[g1]

The standby is not before the OT, so C13 and C14 are suspects.
The voltage being 120VAC could just be coincidence, it does not mean it's coming from the wall. It could be ripple on the main filters.

[xtian]

I replaced all four diode in the recto, D12-15. But your point about 120v being ripple is well taken. I'm going to check it out.

[xtian]

Well, the buzz is indeed improved, but not gone.

[g1]

And it is still there when in standby with power tubes removed?

[xtian]

Yes, in standby, no tubes. Sounds like the buzz when you get your fluorescent lamp too close to your amp. (But I'm not!)

[xtian]

I take it back. Buzz is just as bad as ever.

[xtian]

I guess the evidence leads me to suspect the reservoir caps. Any other possibility?

[g1]

I guess the evidence leads me to suspect the reservoir caps. Any other possibility?

That's what I meant when I mentioned C13 & C14 in post #6, I thought your response in post #8 was after replacing them?

[xtian]

Ah! I read too fast. I replaced only the diodes. We're on the same page: we suspect failing reservoir caps. Thanks.

[oc disorder]

Just a thought here , have one of the transformers in a former life been rotated 45 degrees ?

This could induce hum into the o/p trans but it wouldn't be 120v...