rise to glory

Hi Folks

I've been reading the forum on and off for a while now and unfortunately i've now got a problem with my own amp to share. Basically when I've had valves replaced by a technician they last no time at all. e.g about 10 hours playing. The guy who replaced them last is well respected and knows his stuff about Marshalls as he's worked with them for years.

Each time I've get the amp back it works perfectly however its short lived and before long the volume drops out and theres a sound i can only describe as 'a stormy sea' coming out of the cab. Any time i subsequently switch the amp on this sound can be heard continuously.

When it happened the first time i thought it was just a classic 'valves need replaced job' however it seems there may be a deeper routed problem.

Any Feedback would be much appreciated.

Jesstaa

When was the last time the caps/transformers were replaced? I'm not sure if this is a problem caused by bad caps/transformers. But you never know.

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rise to glory

Now that is a question, I guess the tech may go down that route once i give him another call. Just thought I'd see if anyone else had heard this 'stormy sea' sound

cheers for the reply

American Viking

any possibility of a bias drift or a bad or ungrounded current in the electrical system? using a lot of pedals?
do you have any way of checking the bias to see if it's moving on it's own? i'm not positive that this could be it but if you know how to look into it would be worth checking out.

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-I'd rather be a good liver than have one...

jcmjmp

Try inserting a cable between the effect send and effects return jack to see if that makes a difference. Those jacks can get tired and start causing volume swells and drops.

rise to glory

Tried connecting the effects loop, didn't make any difference unfortunately. Looking at the valves they have a yellow orange glow top and bottom and blue purple centre, which correct me if I'm wrong would indicate they,re still fine. The tech explained that the bias was miles off when he went to set up for the new valves and that he had trouble getting it to an acceptable level, but got they're eventually.

Bias drift may indeed be the issue, I do use a pedal or two so it's wholly possible. Would you be suggesting that the pedal power supply is to blame. Come to think of it it is just a variable voltage adapter, probably not good practice?

Cheers for responses, feel like I'm learning something

Procter2812

my best guess is that one of the transformers has gone.... most probably the power tranny if the tech couldnt get the bias in range properly also if the bias is going lower than standard i know that valves make a white noise/ running water sound... that can happen when they are biased wrong... its happened to me.

Take it to the tech and get him to speacifically check the transformers. i wouldnt imagine the problem would be in the capacitors as you would have a large amount of hum and crackling.

My transformer recently went on my TSL and the syptoms were volume dropping and thin tone... until pop the amp died.

Take it to your tech before the bad part damages anything else such as those valves!!!

Hope i can help you dude!!