dumelow Posted December 1, 2009 Share Posted December 1, 2009 Ive got a big marshall dbs amp, its a 4x10" version of this [url="http://cgi.ebay.co.uk/Marshall-200-Watts-Bass-Amp-15-Inch_W0QQitemZ250536674796QQcmdZViewItemQQptZUK_MusicalInstr_Amplifiers_RL?hash=item3a552645ec"]http://cgi.ebay.co.uk/Marshall-200-Watts-B...=item3a552645ec[/url] its been broken for quite a while, and it hasnt been clear whats wrong with it. it powers up but no sound comes out of the speakers. definately the amp and not a cable or bass or anything. anyways i opened it up and to my surprise i found a valve in it. now this amp was sold to me about 5 years ago, the guy before had it for 3 or 4 years and never mentioned to me there was a valve in it, so im assuming that the valve needs replacing. im wondering if i have to get a specific type of valve to replace, and how i go about doing it. is it simple? should i get a professional to look at it. im hoping to get it fixed soon as I want to sell it on as my gigging days are pretty much over for now. Quote Link to comment Share on other sites More sharing options...
umph Posted December 1, 2009 Share Posted December 1, 2009 i very much doubt it'll be the valve, take it to a tech Quote Link to comment Share on other sites More sharing options...
longtimefred Posted December 1, 2009 Share Posted December 1, 2009 that will be a pre amp valve, cant imagine a duff one of them stopping the amp from working. sure it would just sound pants if that was gone. Quote Link to comment Share on other sites More sharing options...
basshead56 Posted December 1, 2009 Share Posted December 1, 2009 The valve in the DBS is is a preamp valve. Even if t´wer blown/dead, you might still get a faint sound out of it, even a bit distorted. I reckon what you have here is a cooked output transformer. These amps have solid state power outputs. I remember talking to a guy about the head version of this amp awhile back and he had a similar problem (he had been using instrument cable to connect it to his cabs and unaware, ruined the output stage of the amp) Funnily enough, he said that was the second one he owned and was a replacement he got from the store when his first one -blew its output transformer! I´d be very surprised if it wasn´t that, or some dodgy wiring. I wouldn´t go messing with valve replacement unless you know 200% what your doing-it can cause serious problems! Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted December 1, 2009 Share Posted December 1, 2009 [quote name='basshead56' post='671332' date='Dec 1 2009, 05:31 PM']The valve in the DBS is is a preamp valve. Even if t´wer blown/dead, you might still get a faint sound out of it, even a bit distorted. I reckon what you have here is a cooked output transformer. These amps have solid state power outputs. I remember talking to a guy about the head version of this amp awhile back and he had a similar problem (he had been using instrument cable to connect it to his cabs and unaware, ruined the output stage of the amp) Funnily enough, he said that was the second one he owned and was a replacement he got from the store when his first one -blew its output transformer! I´d be very surprised if it wasn´t that, or some dodgy wiring. I wouldn´t go messing with valve replacement unless you know 200% what your doing-it can cause serious problems![/quote] Solid state amps, even with valve preamp, very rarely have output transformers, the Hellborg sig power amp is the only oe I know of. And using the wrong cable has trouble breaking SS amps, unless they break and short, and it overheats. You can break the power transformer though. There are probably fuses in it somewhere, check all of them. The valve is probably a 12AX7, but they don't break easily. Get it to a tech. Quote Link to comment Share on other sites More sharing options...
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