#1
Peavey 6505 112. Power tubes and one other pre amp tube lights. V1-v4 do not. Was looking around the board and found this. Pretty sure this has something to do with tubes not lighting and getting no sound except when plugged into effects loop. Anyone ever seen something like this? Side note. Checked out R82 responsible for tune heating. Resistor checks out with ohm/continuity test.

Between r23 and r39 or near that area.

EDIT:: also changed a preamp tube that appeared to have black smoke or evidence of burning, but that socket is not pictured.
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Last edited by fender4482 at Aug 14, 2016,
#2
MY GEAR!
Amp
-Peavey Classic 30
Guitars
-Silverburst Epiphone Les Paul Custom
-Squier Stratocaster
Pedals
-Ibanez TS9DX Turbo Tube Screamer
-Fender PT-100
-MXR Phase 90
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-MXR Carbon Copy
#3
That looks like a broken trace coming to/from R36 (not sure which way the signal flow is in that amp). Think you could jumper it?
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Quote by Anonden
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#4
Quote by oneblackened
That looks like a broken trace coming to/from R36 (not sure which way the signal flow is in that amp). Think you could jumper it?
Yeah I could. I just don't know if jumping it would fix it. Something had to have caused that to blow. So I'm not sure if jumping it would just smoke the jump too.

EDIT: Not even sure how to jump it. Maybe just solder a spot on?
MY GEAR!
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-Peavey Classic 30
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-Fender PT-100
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-Fuzz Face Clone
-MXR Carbon Copy
Last edited by fender4482 at Aug 14, 2016,
#5
That looks like physical damage, not something that an electrical surge could have done. Circuit boards melt and burn, they don't explode.
Current Gear:
LTD MH-400
PRS SE Custom 24 (Suhr SSH+/SSV)
Ibanez RG3120 Prestige (Dimarzio Titans)
Squier Vintage Modified 70s Jazz V
Audient iD22 interface
Peavey Revalver 4, UAD Friedman BE100/DS40
Adam S3A monitors
Quote by Anonden
You CAN play anything with anything....but some guitars sound right for some things, and not for others. Single coils sound retarded for metal, though those who are apeshit about harpsichord probably beg to differ.
#6
I am still in a very basic knowledge of understanding amp circuits so I'll try to help by talking out my butt until someone else more knowledgeable comes along. Here is the schematic for reference.

R36 is a grid resistor methinks so although the broken(?) trace is definitely a problem, I do not think it would be the reason V1-V4 would not light up. To check if the trace is broken, just check continuity across the right end of the resistor to the other end of the trace, if you can find a good point to poke.

The fact that V5 (the 12AX7 PI) along with the power tubes light up and "work" (going through the effects loop bypasses the main preamp, V1-V4) is curious. It is possible that the resistor may be good but a trace or other component along the way is not. It looks like to me that V5-V7 are "before" V1-V4 in the heater circuit.

Also I presume with the fact that you have the amp open and working with it you are aware that the amp can hold lethal voltages even when unplugged, even when unplugged for a while. If not, now you know and if you do not know how to safely drain filter capacitors and check them, please do not work on it until then.

Also, is that a hole above C48?
Last edited by Will Lane at Aug 14, 2016,
#7
Quote by Will Lane
I am still in a very basic knowledge of understanding amp circuits so I'll try to help by talking out my butt until someone else more knowledgeable comes along. Here is the schematic for reference.

R36 is a grid resistor methinks so although the broken(?) trace is definitely a problem, I do not think it would be the reason V1-V4 would not light up. To check if the trace is broken, just check continuity across the right end of the resistor to the other end of the trace, if you can find a good point to poke.

The fact that V5 (the 12AX7 PI) along with the power tubes light up and "work" (going through the effects loop bypasses the main preamp, V1-V4) is curious. It is possible that the resistor may be good but a trace or other component along the way is not. It looks like to me that V5-V7 are "before" V1-V4 in the heater circuit.

Also I presume with the fact that you have the amp open and working with it you are aware that the amp can hold lethal voltages even when unplugged, even when unplugged for a while. If not, now you know and if you do not know how to safely drain filter capacitors and check them, please do not work on it until then.

Also, is that a hole above C48?
Well it's efinitly a problem. I've got it back together now. Gonna drop it off with a tech at this point. Very familiar with my fluke meter as I use it everyday at work. But thanks for the advice. And yeah that is a hole. Didn't think much of it until you mentioned if. Appears to be a "perfect circle". From factory I suppose, not sure how else a circle that perfect would have been made.
MY GEAR!
Amp
-Peavey Classic 30
Guitars
-Silverburst Epiphone Les Paul Custom
-Squier Stratocaster
Pedals
-Ibanez TS9DX Turbo Tube Screamer
-Fender PT-100
-MXR Phase 90
-Fuzz Face Clone
-MXR Carbon Copy
#8
Quote by fender4482
Well it's efinitly a problem. I've got it back together now. Gonna drop it off with a tech at this point. Very familiar with my fluke meter as I use it everyday at work. But thanks for the advice. And yeah that is a hole. Didn't think much of it until you mentioned if. Appears to be a "perfect circle". From factory I suppose, not sure how else a circle that perfect would have been made.

Thats called a "Via".
It connects one side of the circuit board to the other side. Its normal.

That trace in question coming from R36 looks like a jumper was added to go from that trace to Pin 1 of that tube.

I have seen fried traces before.
An electrical surge can physically damage a trace, basically evaporating a section of it. (I fixed a Mesa Nomad a few months ago that did just that).
And I don't see any evidence of a burned up trace, otherwise that area around the part of the trace would be darker, and black.
Whatever was done there, looks like it was done on purpose.

I would do a continuity check from the right side of R36 > Pin 1 and R36 > Where ever that trace goes to.
From your description, it sounds like it is a problem in the preamp section.
#9
Quote by CodeMonk
Thats called a "Via".
It connects one side of the circuit board to the other side. Its normal.

That trace in question coming from R36 looks like a jumper was added to go from that trace to Pin 1 of that tube.

I have seen fried traces before.
An electrical surge can physically damage a trace, basically evaporating a section of it. (I fixed a Mesa Nomad a few months ago that did just that).
And I don't see any evidence of a burned up trace, otherwise that area around the part of the trace would be darker, and black.
Whatever was done there, looks like it was done on purpose.

I would do a continuity check from the right side of R36 > Pin 1 and R36 > Where ever that trace goes to.
From your description, it sounds like it is a problem in the preamp section.
That looks like a jump to you? I thought it was a crack from maybe pushing in the tube too hard.
#10
Quote by Will Lane
That looks like a jump to you? I thought it was a crack from maybe pushing in the tube too hard.

It looks to me like a solid core insulated wire (about 30 gauge I'm guessing).
I opened the image in my image program and enlarged it.
Looks like on the right end of it, I can see what looks like a wire coming out of green insulation.

And cracks in fiberglass are ALWAYS straight (unless the fiber material itself is curved).

Edited to fix that line ^
Last edited by CodeMonk at Aug 16, 2016,