ZPQ Posted August 26, 2007 Share Posted August 26, 2007 Hi, I plugged in my old GP11 4x10 trace combo this afternoon and it's developed a problem. 90% of he volume has gone and it sounds very distorted. I had a quick look and without doing a full on diagnosis I suspect it's the power transistors that are failing. Anyone had a similar problem or have any thoughts. Thanks John Quote Link to comment Share on other sites More sharing options...
neilb Posted August 26, 2007 Share Posted August 26, 2007 Im sure Oxblood will have some suggestions, hes pretty well expert on amps and the best band in the world, aint you Ox? Quote Link to comment Share on other sites More sharing options...
Jean-Luc Pickguard Posted August 26, 2007 Share Posted August 26, 2007 Gavin at GM audio fixed mine: [url="http://www.gmaudio.co.uk"]http://www.gmaudio.co.uk[/url] GM audio is a Trace Elliot affliated authorised service centre and used to do all the warranty work for them. Quote Link to comment Share on other sites More sharing options...
ZPQ Posted August 26, 2007 Author Share Posted August 26, 2007 Thanks for the link, it's a bit too far for me, but if I haven't traced (;-) ) the fault by tuesday I'll give them a ring and see if they have an schematics/service docs. Cheers John Quote Link to comment Share on other sites More sharing options...
Oxblood Posted August 26, 2007 Share Posted August 26, 2007 Dunno wot you mean, mate. I just prop up the bar and try not to get in anyone's way. As for the Trace Combo: I'm a valve man meself, but if I can be of any help on the ideas front.... ZPQ: Sorry for stating the bleedin' obvious, but on this amp, is there any way of intercepting the signal path as it passes from the pre-amp to the power stage? If so, you could take a feed off the pre and check if it sounds clean, and maybe feed a line-level signal into the power amp and see what that sounds like. Next blindingly trite observation: it's not the old "dead batteries in my active bass/effects unit" scenario, by any chance? Anyone else got any bright ideas? Quote Link to comment Share on other sites More sharing options...
Subthumper Posted August 26, 2007 Share Posted August 26, 2007 is there any way of intercepting the signal path as it passes from the pre-amp to the power stage? Sounds like a good place to start,try cleaning all the send and return FX loop jacks, especially the shorting contacts which will require removing the amp from the cab(make sure its unplugged).Also worth cleaning the master vol pot.Sounds unlikely to be the power transistors as they usually go dead short when they blow and then take out the power supply fuses. If none of these work then best to take it to a proper techie. Good luck Cheers Just Quote Link to comment Share on other sites More sharing options...
ZPQ Posted August 26, 2007 Author Share Posted August 26, 2007 Thanks for the replies, Just had another look at it. Cleaned the pots and sockets - no change. Lots of brown gunk inside it - yuck. Connecting the send and return makes no difference, but there is a line in and connecting the send to this and it seems to work. Can't crank it up at this time of night, but it suggests that the fault is in the preamp and somewhere around output gain and end of the preamp chain (line in appear to after this in the chain - which I think is a bit odd). Thanks John Quote Link to comment Share on other sites More sharing options...
bw_user_name Posted August 26, 2007 Share Posted August 26, 2007 ahh, ... I always ran it through the PA and it sounded well good .. 10 yrs in the garage might have F**Ked the speakers ? it's cold up North. Quote Link to comment Share on other sites More sharing options...
bw_user_name Posted August 26, 2007 Share Posted August 26, 2007 See you down the Rampant Horse, OPE Quote Link to comment Share on other sites More sharing options...
ZPQ Posted August 26, 2007 Author Share Posted August 26, 2007 Hi Mick, My last test connecting the send and line in worked fine so I think the speakers are ok, something in the preamp at the end of the signal chain I think. If I can find a schematic then I think it'll be an easy fix. Quote Link to comment Share on other sites More sharing options...
ZPQ Posted August 26, 2007 Author Share Posted August 26, 2007 [quote name='bw_user_name' post='51095' date='Aug 26 2007, 11:56 PM']See you down the Rampant Horse, OPE[/quote] ? Unlikely you'll find me in that part of town - are you going there or something? Quote Link to comment Share on other sites More sharing options...
bw_user_name Posted August 26, 2007 Share Posted August 26, 2007 Sorry it didn't work as thought, Yeah, the Rampant is where we go when in Hull .. are you living near ? Quote Link to comment Share on other sites More sharing options...
ZPQ Posted August 26, 2007 Author Share Posted August 26, 2007 No, I'm on the opposite side of town, just near the Humber bridge. I used to teach near there though. Quote Link to comment Share on other sites More sharing options...
bw_user_name Posted August 26, 2007 Share Posted August 26, 2007 so youre a beech tree man then ? Quote Link to comment Share on other sites More sharing options...
ZPQ Posted August 26, 2007 Author Share Posted August 26, 2007 Yes I go in there now and again. You must work in the pub trade (or related), no one could know all these pubs.... could they? Quote Link to comment Share on other sites More sharing options...
bw_user_name Posted August 28, 2007 Share Posted August 28, 2007 Pub tourism is a hobby of mine, Hope you get the amp sorted soon. Quote Link to comment Share on other sites More sharing options...
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