TR!ΔNGL€ T€€TH Posted June 26, 2010 Report Share Posted June 26, 2010 I am having problems with my Marshall JTM 60 3x10, namely that it is not producing any sound. This problem first appeared whilst I was soundchecking for a gig, so the amp was on and there wasn't any spectacular explosions or anything, just no sound when I turned the standby off. I've checked the obvious things, the speaker cable is fine, the amp is coming on and the mains fuse is okay. There is no sound at all coming from the speakers, but I can hear the amp switching between channels. The valves are lighting up, but I suspect that they are the problem. There are four ECC83's in the preamp stage and two EL34's in the power amp stage.I am thinking that my best bet would be to take it into R'n'B or Bruce Millers and have an expert look at it, but I thought I would post and see if anyone had any ideas? Especially any way of narrowing down what the problem is. Quote Link to comment Share on other sites More sharing options...
Soda Jerk Posted June 26, 2010 Report Share Posted June 26, 2010 Might be the power amp valves. If it was the preamps, you'd get at least a bit of microphonic feedback. If you can hear the channels changing, then that may possibly rule out the chance of it being the dreaded output transformer too. But I don't even know what I'm basing that on. Quote Link to comment Share on other sites More sharing options...
sonhenry Posted June 26, 2010 Report Share Posted June 26, 2010 It needs to go to the shop. Unless something is loose, no sound is a blown output tranny or something else. Not likely to be power tubes unless you're blowing fuses. Are you sure the speakers are ok? And the speak wire is fine? Quote Link to comment Share on other sites More sharing options...
givemeasmile Posted June 26, 2010 Report Share Posted June 26, 2010 I need mine looked at too, how much d'you reckon it'd cost for one of our local music shops to check an amp out? Quote Link to comment Share on other sites More sharing options...
TR!ΔNGL€ T€€TH Posted June 27, 2010 Author Report Share Posted June 27, 2010 Thanks for the advice, I guess a trip to R'n'B or Bruce Millers is in order. Any idea how much it'll cost? Quote Link to comment Share on other sites More sharing options...
Lame Guitarist Posted June 28, 2010 Report Share Posted June 28, 2010 Could be internal fuses if that amp model has any. Had the same issue before with amps, some fuses can blow on the circuit board but the amp will still power up but have no sound. If it is that they are easily replaced and can maybe just signal a faulty power tube Quote Link to comment Share on other sites More sharing options...
Roscoe 5 Posted June 29, 2010 Report Share Posted June 29, 2010 My HT fuse kept blowing in my dsl 100 resulting in no sound coming from the amp.Turns out a dodgy cab at cpt toms resulted in my transistor blowing and knocking out 2 valves at the same time.Took it to Kennys music in Dundee - sent it to Marshall free of charge and fixing it for free because its still under warranty. Quote Link to comment Share on other sites More sharing options...
HateEvent Posted June 29, 2010 Report Share Posted June 29, 2010 R&B don't charge anything to look at your amp.If need be, it'd get sent back to Marshall to get checked out. If it's a combo it's 40 to put to them (25 for a head) (this is when out of warranty) and they will assess it and then get in contact before doing any work. R&B could change the valves and see if that was what the problem was without needing to send it away. Maybe a wise idea as a first port of call if they haven't been changed in a long time and it's been used a lot. Quote Link to comment Share on other sites More sharing options...
givemeasmile Posted June 29, 2010 Report Share Posted June 29, 2010 R&B don't charge anything to look at your amp.If need be, it'd get sent back to Marshall to get checked out. If it's a combo it's 40 to put to them (25 for a head) (this is when out of warranty) and they will assess it and then get in contact before doing any work. R&B could change the valves and see if that was what the problem was without needing to send it away. Maybe a wise idea as a first port of call if they haven't been changed in a long time and it's been used a lot. Well I changed my valves a month ago because of this crackling noise that was happening, I don't know much about valve amps and presumed that'd be the issue due to naivety. But this crackling happens even when there's nothing going through the amp, there doesn't even have to b ea lead plugged in. The amp still sounds good and you can't really hear it when you're playing. but it's a pain in the arse on stage between songs. I think it's probably the electrics, is there anybody in town who could fix this? Quote Link to comment Share on other sites More sharing options...
Lame Guitarist Posted June 29, 2010 Report Share Posted June 29, 2010 Well I changed my valves a month ago because of this crackling noise that was happening, I don't know much about valve amps and presumed that'd be the issue due to naivety. But this crackling happens even when there's nothing going through the amp, there doesn't even have to b ea lead plugged in. The amp still sounds good and you can't really hear it when you're playing. but it's a pain in the arse on stage between songs. I think it's probably the electrics, is there anybody in town who could fix this?Do you have an effects loop in your amp? If you do can you plug a short patch cable into the send and the other end to the return, then try again and see if the problem clears? Quote Link to comment Share on other sites More sharing options...
TR!ΔNGL€ T€€TH Posted June 29, 2010 Author Report Share Posted June 29, 2010 R&B don't charge anything to look at your amp.If need be, it'd get sent back to Marshall to get checked out. If it's a combo it's 40 to put to them (25 for a head) (this is when out of warranty) and they will assess it and then get in contact before doing any work. R&B could change the valves and see if that was what the problem was without needing to send it away. Maybe a wise idea as a first port of call if they haven't been changed in a long time and it's been used a lot. Cool, cheers for replying. I think that I'll be taking it down once I get a hand with transport. I assume that I'm best calling in advance, rather than just appearing with my faulty amp? Quote Link to comment Share on other sites More sharing options...
HateEvent Posted June 29, 2010 Report Share Posted June 29, 2010 Cool, cheers for replying. I think that I'll be taking it down once I get a hand with transport. I assume that I'm best calling in advance, rather than just appearing with my faulty amp?Consider this thread your call in advance - I'll let the others know that you'll be down at some point Quote Link to comment Share on other sites More sharing options...
givemeasmile Posted June 30, 2010 Report Share Posted June 30, 2010 Do you have an effects loop in your amp? If you do can you plug a short patch cable into the send and the other end to the return, then try again and see if the problem clears?BOOM and it's fixed! nice one! anyone want to buy it? haha Quote Link to comment Share on other sites More sharing options...
Lame Guitarist Posted June 30, 2010 Report Share Posted June 30, 2010 BOOM and it's fixed! nice one! anyone want to buy it? hahaSeen this problem on a few amps and took me a while to figure out what was going on. Its just the effects loop jacks building up dust or dirt and giving a bad connection and this cuts out sound at times or gives noise and crackle. When you put a cable between them it solves the connection break. You are best opening the amp and gently rubbing the metal parts of the jacks with a flat head screwdriver and cloth. Don't use electrical solvent cleaner unless your confident you won't get any on the circuits. That stuff is good but can corrode circuit boards and stuff if it gets near Quote Link to comment Share on other sites More sharing options...
Monk Rocker Posted June 30, 2010 Report Share Posted June 30, 2010 I'm glad I read this thread! I'm having the exact same prob - I'll try the effects loop fix tonght:-) Quote Link to comment Share on other sites More sharing options...
triggs Posted June 30, 2010 Report Share Posted June 30, 2010 best guy to see is dennis marshall in dunfermline dennis marshallforget brucies or r&b. quite often depending on the job he'll do it while you wait Quote Link to comment Share on other sites More sharing options...
britheguy Posted June 30, 2010 Report Share Posted June 30, 2010 best guy to see is dennis marshall in dunfermline dennis marshallforget brucies or r&b. quite often depending on the job he'll do it while you waitAh! wide words from Triggs the Fender Blaster Master. That bloody Fender he did is awesome:up: Quote Link to comment Share on other sites More sharing options...
toiletbag Posted June 30, 2010 Report Share Posted June 30, 2010 best guy to see is dennis marshall in dunfermline dennis marshallforget brucies or r&b. quite often depending on the job he'll do it while you waitThis man speaketh the truth! Quote Link to comment Share on other sites More sharing options...
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