My Marshall has blown again

[bucketshred]

TBH, I've wanted a new amp for a while so this seems like a good opportunity to get one. I'm not impressed with Marshall at all at the moment.

Paddy

[JacksonRR]

Not all OTs are balanced. Some will measure way off and that's OK. It's one of those little things no one tells you on those valve sites that go on and on about matched phase inverter tubes. What's the point when even matched power tubes aren't matched perfectly? It's snake oil.

To the OP: Yeah I got the feeling you didn't want it anymore, but a working Marshall is worth a lot more than a dead one when you're trying to cut your losses. I love picking up dead amps, but it makes me feel guilty at the same time. Most of the time it's something real cheap and easy to get it back to a deserving price. Open that sucker up and follow the leads coming off of the power tranny. Do you see anything funny in that area? Bubbled out capacitor, bad connector, cold/broken/bad solder joints or burnt up resistors? Don't touch anything unless you've drained the filter caps, cuz that'll solve your amp problems for good.

[bucketshred]

Mate, I know nothing about amps. My plan is to take it to Marshall, complain, get it fixed and then flog it to fund a new amp.

Bloody cr@p timing too considering I've just joined a new band.

Humph.

Paddy

[ShredHeadJHJ]

Sell it and buy a Splawn Quick Rod or Pro Mod. Bye bye Marshall!!!

That being said, I finally got a chance to (extensively) play a 4 channel JVM with some good volume through a Soldano cab. That thing killed. Very very good sounding head, and great cleans. Still not on par with my Quick Rod though.

[Dmoney]

if your tubes aint lit, then there is no heater voltage going to them. that is usually a separate feed from everything else.
it usually feeds your indicator light too but not always!

you might have a bad valve that has blown the heater fuse, or something similar to toe-knees problem. that could be it.

Is your amp is under warranty? marshall charge £25 an hour + parts to diagnose and fix a fault I think.

JacksonRR. yeah, that measuring test is defo not a dead cert. I had to check my old O'netics OT that way, it measured the same each side... but really low readings compared to other trannies, but I checked it was in spec with the builders and they told me it was. You can't do a proper check on transformers unless you have special kit I think?

[JacksonRR]

Yeah if you do decide to save the cash and open her up and you find a blown fuse, first thing is yank those power tubes. Fuses are awesome when they work out, but sometimes they don't and when you're valve fails in an awesome light show(I peed a little my first failure, jk), it may take out more components. But if you'd rather take it to a tech and be done with it, you may be better off selling it broken. Well I wish you best of luck finding the new amp, man.

[Transcend]

I had a similar problem to this a while back and it just turned out to be the heater fuse that had blown.

Nice cheap & simple fix not had a single problem since

[Twinfan]

Yep, if no valves are lighting I'd check the heater/mains fuses.  If one or both have gone try a fresh one and see if that pops too.....

[Telerocker]

What about the on/off button? I had mine once broken.

[JacksonRR]

So what's going on with it Bucketshred? Any news?

[bucketshred]

Well there is the possiblity of me getting it fixed for a very low price in the new year by a mate of mine. He is out of the country at the moment. Once that is done then I'm flogging it and going amp shopping :D

Paddy

[JacksonRR]

Sounds good man. When it gets fixed can you post what had happened with it? I'm curious....

[hunter]

You didn't you use the same speaker cable by any chance?

Good point!

Do all the valves fire up and glow?  Are all the fuses OK?

None of the valves glow at all.

Paddy

That means 98% it's a fuse that has blown. Could just have blown because of an electricity spike or because of a bad tube, resistor or whatever.

Check fuses.
Replace blown fuse.

Try and see.

[HTH AMPS]

is there ANYTHING powering up in the amp at all?

you say that the valves don't glow, but does the mains on/off switch light up?

if NOTHING is lighting up, it could just be the mains fuse - they do occasionally pop even without anything being 'wrong'.

if the mains lights up but the heaters don't, then it'll be a fuse on the heaters like others have suggested.

it'll not likely be very much wrong.

[JacksonRR]

is there ANYTHING powering up in the amp at all?

you say that the valves don't glow, but does the mains on/off switch light up?

if NOTHING is lighting up, it could just be the mains fuse - they do occasionally pop even without anything being 'wrong'.

if the mains lights up but the heaters don't, then it'll be a fuse on the heaters like others have suggested.

it'll not likely be very much wrong.

Had this on a Laney GH50L. Replaced the fuse, fired it up, EL34 lit up with sparks, took out a resistor and both mains fuses. First fuse saved the surrounding components when the tube failed, second time not so lucky. Is there any sign of power tube failure or old age?