#1
As the title says, the clean and crunch channels on the amp are are completely dead. I was playing on the clean channel minding my own business until the signal suddenly cut out and I have not managed to get it to run again.

No sound at all and only when I turn the post gain up, I only hear a small amount of hiss as is normal when an amp is turned up so loud, but there is no guitar signal whatsoever. And yes, I did adjust both the pre gain and the post gain on the clean channel. When I adjust the EQ on the clean channel, the hiss does change in sound. So the EQ seems to be fine.

Lead channel works completely fine too. So the section of the amp governing it is not the problem.

What sections of the 6505+112 govern exclusively the clean channel?

The preamp tubes glow and look completely fine. There's nothing microphonic there. Power section is obviously fine otherwise the lead channel wouldn't be working either.

I may get the amp apart and poke around for anything that's gone obviously wrong. But if its anything obvious then please let me know.

I guess this means that my soon-to-be-purchased Boss CE-5 is going to be a bit of a redundant one unless I can get this amp working again.

Not that the cleans of this amp are very good or anything, but that's not really the point. It's broken and it needs fixing.
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Last edited by T00DEEPBLUE at Apr 10, 2016,
#2
Half of V1 and half of V2 are clean/crunch. It's possible that either of them has partially failed. I'll look at the schematic later when I get a chance.
“Ignorance more frequently begets confidence than does knowledge.”
Charles Darwin
#3
I have had that problem before only it was the opposite, the clean/crunch channel worked but the lead channel was dead. All it was was a bad preamp tube, and if memory serves it was in V2. (It was either V1, V2, or V3). The tubes all still lit up, but the one that was the culprit just didn't work on one side.
Atmospheric dark metal w/ black and death metal influences:
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#4
My guess is V2 is 1/2 bad. You can try a 12DW7 in there to get the clean channel cleaner but not touch the Lead channel.
Guitars:
Jackson Kelly KE3 - MIJ (Distortion/Jazz)
Jackson DKMGT Dinky (EMG 81/85)
ESP E-II Eclipse Custom (JB/'59)
ESP LTD EC-1001FR (EMG 81/60)
Fender MIM Strat

Amps:
Mesa/Boogie Dual Rectifier Roadster 212
Laney IronHeart IRT-Studio
Peavey Vypyr 30
Peavey ReValver Amp Sims
TOOOO many T.C. Electronic Pedals. . .
#5
I've opened up the amp and I've found nothing glaringly wrong at all.

I'm worried now that there's either a bad solder joint or a track has partly broken on the PCB.

I've just plugged in the amp again and the amp's clean/crunch channel is alive again, so its an intermittent fault.
Quote by Axelfox
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Last edited by T00DEEPBLUE at Apr 10, 2016,
#7
Intermittent issues are the worst. I'd clean all of the preamp tube sockets with contact cleaner and pick up some 12ax7, 12DW7, and 5751 JJs and have at it.

You can apps try swapping V2 with the slot for the FX loop - V4 I think - I'm used to the non plus.
Guitars:
Jackson Kelly KE3 - MIJ (Distortion/Jazz)
Jackson DKMGT Dinky (EMG 81/85)
ESP E-II Eclipse Custom (JB/'59)
ESP LTD EC-1001FR (EMG 81/60)
Fender MIM Strat

Amps:
Mesa/Boogie Dual Rectifier Roadster 212
Laney IronHeart IRT-Studio
Peavey Vypyr 30
Peavey ReValver Amp Sims
TOOOO many T.C. Electronic Pedals. . .
#8
I'll purchase a 12DW7 and see if that rectifies the fault, even though absolutely nobody in the UK sells them. Not even online. Getting one shipped from the US will cost me a bomb.

There isn't much I can do if there actually is a break in any of the traces. Even though that is unlikely to happen.
Quote by Axelfox
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Last edited by T00DEEPBLUE at Apr 11, 2016,
#9
Quote by T00DEEPBLUE
I'll purchase a 12DW7 and see if that rectifies the fault. There isn't much I can do if there actually is a break in any of the traces. Even though that is unlikely to happen.


Simple enough to bridge with a little piece of wire and some solder.
“Ignorance more frequently begets confidence than does knowledge.”
Charles Darwin
#10
Well the problem isn't so much the action of bridging the break, the real problem is knowing which trace is broken and where.
Quote by Axelfox
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#11
Quote by T00DEEPBLUE
Well the problem isn't so much the action of bridging the break, the real problem is knowing which trace is broken and where.


That's always the case. If you can't read a schematic and relate it to the physical circuit you're pretty much SOL.

I'd try a couple of new tubes first, that's a much more likely problem and having a few extra never hurts.
“Ignorance more frequently begets confidence than does knowledge.”
Charles Darwin
#12
Quote by T00DEEPBLUE
I'll purchase a 12DW7 and see if that rectifies the fault, even though absolutely nobody in the UK sells them. Not even online. Getting one shipped from the US will cost me a bomb.

There isn't much I can do if there actually is a break in any of the traces. Even though that is unlikely to happen.


You don't need to run a 12DW7. Any 12AX7 will work -- just buy one you know you'd buy anyway.

I have a 12DW7 that I've run in V2, and it does a wonder to the cleans -- but ultimately I only put it in when I'm recording cleans. It shouldn't do anything to my lead channel tone, ----- but it does. I don't know why, because it's supposed to be a normal 12AX7 gain-factor on that side. But to my ears it sounds like it really cuts the gain and some of the balls and saturation is missing. It could be just the particular tube I bought.
Atmospheric dark metal w/ black and death metal influences:
(My Soundcloud page):

Pestilential Flood