No sound out of my AMP!!! ???

[Pete L]

Hey Mates - I have a 86' Marshall Studio 15 combo (the 6V6 15 watter).

Running fine until the other day....it still fires up fine, all tubes lit, etc...plug in however and NOTHING, NO SOUND...not even scratchiness, pop, etc,,,,,the speaker is plugged in. My initial thought is the INPUT jack crapped out??? I pulled the chassis - the jack appears to be gripping the plug - but who knows?

Does this sound like the culprit? Given abrupt nature and NO sound, I'm just thinking it has to be the input jack....coul it be anything else?

Thoughts???? Much appreciated.

 

[601 Blues]

Standby switch??? I had an amp once that acted like that and I had ta flip the standby a couple times!!Just a thought!

 

[Adwex]

Fuse?

Not the mains fuse, obviously.

 

[thegaindeli]

You can have a failed preamp tube that's lit! Replace each tube - one at a time.There are a large amount of bad "long-plate" Russian 12AX7's going around right now.Ideally you should put in a complete set that you know is good.

 

[felim]

Check the HT fuse first, if that's gone, you'll get no sound but visually everything will seem to be working, pilot light and valves will all light up.

 

[PaoloJM]

As there is no sound what-so-ever it might be worth-while ruling out the speaker as the problem first.
To check both the wiring and the speaker itself simply power down the amp and unhook the speaker cable. Take a 9Vdc battery and place the terminals across the speaker lead with negative terminal to the sleeve and positive to the tip.
You should hear a pop and the cone should move to it's forward position. Remove the battery once your test is done as DC is not good for speakers (this short test wont do any harm however).

 

[stookiebhoy]

This happened to me a few weeks ago and it was the transformer that had given up on me so it may be that.

 

[Floydfanatic]

I had this happen to my DSL 100 a few months back. It was a resistor that had fried on the control board. That allowed more current to come through than was supposed to.

This fried the fuse (which I had replaced), which led to 2 tubes running super hot and ruined.

Anything that sudden after working correctly smells strongly of a fuse-related incident to me.

 

[Pete L]

Many thanks for the suggestions - It was the preamp tubes - I swapped in a pair of 12AX7's out of my Fender DRRI.......sweet mother of jesus!!

Would you believe the factory "Fender" GT's have made this amp sound better than it ever has- way sweeter/smoother OD clip? And it sounded great before with nice JJ's....I think i'm giving up on this tube snobbery BS.

Thanks again Mates! Rock on. Pete