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The sound of silence....


thunderstruck507

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So the other night some friends and I were jamming my Epiphones in the living room and all was well. Turned it all off and crashed. Today I turned the amp on and went to do some stuff around the house to come back to a nice toasty tube amp...

 

Well I plug in and turn on and get nothing.

Change cords, still nothing.

Checked the fuses, both look ok, and the power amp tubes are glowing red like normal.

But I can't see light coming from the preamp tubes at all (don't recall them ever glowing much like the power amp tubes anyway though).

 

Jiggled the power chord, checked all channels, nothing but a light hum no matter what.

 

Speaker is plugged in as well, havent tried plugging in the cabinet to it though.

 

Amp is the marshall dsl401

 

any ideas?

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Hmmmm I'm not an amp tech person at all. But, I was warned, some time ago, about possible power transformer

problems in that model of Marshall. Not saying that's what it is...might just be a bad pre-amp tube? If you have no

other (extra) tubes, to check it out...take it to a qualified service person, ASAP...I'd say. Best do minimal messing

around with amps, unless you are really familiar with them, as they can shock the Hell out of you, at best, and kill you

at worst. So...see a "Pro!"

 

CB

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Hmmmm I'm not an amp tech person at all. But' date=' I was warned, some time ago, about possible power transformer

problems in that model of Marshall. Not saying that's what it is...might just be a bad pre-amp tube? If you have no

other (extra) tubes, to check it out...take it to a qualified service person, ASAP...I'd say. Best do minimal messing

around with amps, unless you are really familiar with them, as they can shock the Hell out of you, at best, and kill you

at worst. So...see a "Pro!"

 

CB[/quote']

 

my transformer has been replaced before, it used to sound weak until I bumped it hard, then would come on strong, so I took it and they replaced it.

 

This time it didn't do anything funny...just stopped working. I'm guessing something in the preamp is messed up since I'm sure they should at least look "on" right?

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Go SLOW. You're in a no panic zone. Don't assume amp failure..., don't assume anything. I've not heard of a tube amp OT going down that way.

Process of elimination is your best friend.

 

Try:

1. check all your plug connects and roll your volume pots up/down

2. tap on your guitar pup (whichever is switched on) -- still nothing?

3. plug a different guitar into that amp

4. plug your cab into it, still nothing?

5. plug your guitar into a different amp if possible... report back results if still nothing.

 

Hit every BLUE NOTE baaaby..., I'm going to play on:-"

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CB is right. That particular model suffered from overheating in the first version. Among other things it was biased too hot.

Since I bought the same one I made sure I bought the improved version. A built-in fan is a common mod if you have an old one.

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CB is right. That particular model suffered from overheating in the first version. Among other things it was biased too hot.

Since I bought the same one I made sure I bought the improved version. A built-in fan is a common mod if you have an old one.

 

When did they make the "improvement"/Change, Ricochet? And, did they rebias

it (cooler)? I never get to see/check out any of this stuff, anymore, as I'm out in the 'Sticks"

hours away, from the nearest dealer(s).

 

CB

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When did they make the "improvement"/Change' date=' Ricochet? And, did they rebias

it (cooler)? I never get to see/check out any of this stuff, anymore, as I'm out in the 'Sticks"

hours away, from the nearest dealer(s).

 

[/quote']

 

Since it obviously isn't an issue for my amp, I completely forgot the specifics(otherwise I would have mentioned them)... I'm not sure of the when.... I think I went by the serial on the back... It's still biased too hot but holds up well.

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Yeah I've tried both mine and rolled every knob on the thing' date=' tapped it all over and such. I'm gonna pull the rear cover and look at the tubes and sockets and see if anything looks amiss.[/quote']

Okay.

Don't rely on the "looks" test for fuses. Check for continuity.

Inside first do a visual for dark/burned spots and loose wires especially the speaker wires at both connect ends. If nothing, then power on and use the "chopstick method" (wood or other non- metal probe) to tap tube bases, circuit board connects, OT, etc. Report back. I'm leaving for work but others can help - try PM to Eracer_Team, cgil, or layboomo who are the amp tech gurus.

 

Hit every BLUE NOTE baaaby..., I'm going to play on:-"

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Okay.

Don't rely on the "looks" test for fuses. Check for continuity.

Inside first do a visual for dark/burned spots and loose wires especially the speaker wires at both connect ends. If nothing' date=' then power on and use the "chopstick method" (wood or other non- metal probe) to tap tube bases, circuit board connects, OT, etc. Report back. I'm leaving for work but others can help - try PM to Eracer_Team, cgil, or layboomo who are the amp tech gurus.

 

Hit every BLUE NOTE baaaby..., I'm going to play on:-"

 

the tubes come out of a metal shield so I can't tap them near there without disecting the whole amp section of the cabinet, and really dunno how comfortable doing so anyway, guess I'll take it to the shop tomorrow

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I'm leaving for work but others can help - try PM to Eracer_Team' date=' cgil, or layboomo who are the amp tech gurus.

 

Hit every BLUE NOTE baaaby..., I'm going to play on:-"

 

Do you know if any of these gents do repair work?

I have one of the 1st Univox 4 channel 105w hybrids ever made (ser # 235) that needs some work.

The spring reverb shorted out, about 1/2 the tubes blew, and it literally MELTED all the wiring in

my LP,(which I had repaired straight away).

I'd LOVE to get it going again,(it was a deathbed gift from a good friend) but nobody in my area will touch it.

I have pics of the amp if needed.

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I used to have a Vjr head that occasionally did exactly as you describe. The only thing that ever worked was turn all power switches on, then pull the plug. Count to 10, shut off main switch. Plug back in, turn on and see what happens. Nobody could ever explain what happened, or why it worked again if you did exactly these steps. Try. Nothing to loose.

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