Bare Knuckle Pickups Forum
Forum Ringside => Tech => Topic started by: MemoryLeak on September 24, 2009, 07:37:54 PM
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Hi, I was wondering if anyone had any idea what's wrong with my amp before I a) pay someone to look at it, or b) spend a lot of time on reading up how to fix valve amps! Its a Laney LC30 which I've had for 10 years ish, and its been pretty robust over time, changed the valves a few years ago but otherwise not needed anything doing.
Recently however, its started going silent for about 5-10 seconds at a time every 20 seconds or so. This only happens once I've been playing for about 10 minutes. It sort of fades up and down as well (albeit quickly), its not like a loose connection snapping on and off. Any ideas?
Any help much appreciated!
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Hiya ( and welcome ! ). :)
First things first, have you gently tapped each valve (side ) with a pencil to see if that valve ( as a consequence ) starts to crackle, or bursts into life / silence uopn demand ?
I am thinking either the valve is on it's way out ( average life 1-2 years ) - or a dry joint on the solder that holds the pins, due to cummulative heat e.t.c.
Also, try spraying the pins and sockets with Servisol switch cleaner from Maplins, to see whether you have the same problem through crud / oxidisation on the pins.
:)
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sounds like a filter cap gone bad - classic symptom with the sound fading in/out.
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Thanks for the replies. The valves seem to be glowing ok, and all look the same, so I suspect its the caps. Is this something I can sort myself, I see something about needing a variac to bring them up to voltage. If this is the case I think its professional time.
Any recommended amp techs in Manchester or surroundings?
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I'm sure Martin of MJW Amps is in the Manchester area - he's a regular poster here.
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Thanks for the replies. The valves seem to be glowing ok, and all look the same, so I suspect its the caps. Is this something I can sort myself, I see something about needing a variac to bring them up to voltage. If this is the case I think its professional time.
Any recommended amp techs in Manchester or surroundings?
I would contact Martin, your amp is 10 years old so you should treat it to a pro makeover...
http://www.martamp.com/
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... I suspect its the caps. Is this something I can sort myself
Depends how experienced you are with electronics and soldering. Bear in mind that valve circuits operate at potentially lethal voltages and remember they can retain enough charge if the caps to give you a very severe jolt, even when they're been switched off for some time.
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sounds like a filter cap gone bad - classic symptom with the sound fading in/out.
Indeed it was. Finally got round to fixing this, cost me £6.95 for a new cap and all is well. And I didn't kill myself. Result.
Thanks for the help all!
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sounds like a filter cap gone bad - classic symptom with the sound fading in/out.
Indeed it was. Finally got round to fixing this, cost me £6.95 for a new cap and all is well. And I didn't kill myself. Result.
Thanks for the help all!
no problem, glad you got it sorted.