teen t-shirt Posted July 5, 2010 Share Posted July 5, 2010 i own a Vintage Marshall Bass Combo and its a great sounding amp... when the fecking thing works its (since i took ownership of it) been crackling when i turn certain knobs to adjust certain things, not only does it crackle but it also loses volume so i adjust the volume to bring it back to where it was and it then stays there but then crackles back into life at increased volume which can be a pain in the arse some times when i'm trying to practice... the only control which causes a crackling sound is the Contour control, the volume dip however can occur at random times i could be playing through it for an hour and it wont happen or i could be playing through it for 5 minutes and it will crackle and the volume dip will occur, its just completely unreliable, its a marvelous amp but i can't trust it to gig with, i'm just glad i have my Peavey TKO75 which has been my work horse but just doesnt have the balls for what i need anymore so need to try and fix the marshall. here's the details and specifications for the amp: 200 Watts. Serial No. 5319 50/60hz (240v mains) Model No. is unfortunately unreadable as the amp is so old it was written on the back and has since faded. Any help you guys can give me as to what might be wrong or what the next step should be in fixing this problem or if you reckon i should just take it to a shop or is this a problem i can sort my self. thankyou for any comments and help. Teen T-shirt (Freddie) Quote Link to comment Share on other sites More sharing options...
Al Heeley Posted July 5, 2010 Share Posted July 5, 2010 Pretty sure its some filth on the pot tracks causing both cracking and shorting to give drop in volumes. i had this with a Marshall 30th anniversary valve amp too - exactly what you are describing. Took it to a friend of mine who is an amp technician, he took the amp head out of the cab and cleaned all the pots properly, problem gone. A squirt of contact cleaner spray and a few twiddles does the job on the pots. If it is really vintage, a couple of the pots may need replacing if the tracks have become too corroded or fluffed up. Worth paying for the job to get done properly unless you are confident and handy with a soldering iron. Quote Link to comment Share on other sites More sharing options...
teen t-shirt Posted July 5, 2010 Author Share Posted July 5, 2010 good to know i'm not the only one who has suffered this, yeah am fairly handy with a soldering iron so i'll open her up and give her a good clean if i get chance to put a picture up i will but thankyou for the advice and help much appreciated cos i just didnt know what to do. Quote Link to comment Share on other sites More sharing options...
GarethFlatlands Posted July 5, 2010 Share Posted July 5, 2010 Does it have a headphone out? A dodgy connection there can lead to volume issues as the amp keeps flicking between speaker and headphone out, assuming plugging 'phones in cuts the speaker off. A quick blast of contact cleaner might help there before you open her up and fire up the soldering iron. My old valvestate combo had a similar problem that a good thwack would sort out. Turned out to be the above and the big capacitors inside becoming loose and needing re-seating/gluing. Quote Link to comment Share on other sites More sharing options...
teen t-shirt Posted July 5, 2010 Author Share Posted July 5, 2010 [quote name='GarethFlatlands' post='886717' date='Jul 5 2010, 09:52 PM']Does it have a headphone out? A dodgy connection there can lead to volume issues as the amp keeps flicking between speaker and headphone out, assuming plugging 'phones in cuts the speaker off. A quick blast of contact cleaner might help there before you open her up and fire up the soldering iron. My old valvestate combo had a similar problem that a good thwack would sort out. Turned out to be the above and the big capacitors inside becoming loose and needing re-seating/gluing.[/quote] i dont think it does but i will double check, i'm going to be going to my local music shop on wednesday so i will tell them the same thing i have told you guys and see what they suggest... but thankyou everyone for your comments and advice i will take it all on board and i'll let you know if i solve the problem Quote Link to comment Share on other sites More sharing options...
Big_Stu Posted July 13, 2010 Share Posted July 13, 2010 Don't know if you're aware, but a Marshall dealer is only endorsed by them to sell the amps, not to fix them. I got caught the hard way with that, spoke to Marshall & they have a very friendly, very good service dept who not only fix your problem but overhaul the amp top to bottom to check for anything else. They were even cheaper than the shop who had done a botched job on a combo I had, which coincidentally was a crackly pot. You're not that far from them to either take it yourself for a day out or for a courier to take it. I'd never go anywhere else with a Marshall now. I was given the full tour last year around the factory & was shown the service area with the amps waiting to be fixed - from world-wide........ If you look closely, yes that is Gary Moore's name on the water damaged cardboard box near the back. "NO preferential treatment HERE" they said. Quote Link to comment Share on other sites More sharing options...
Al Heeley Posted July 13, 2010 Share Posted July 13, 2010 Hey - theres my Marshall 115 extn cab I sent back as the crossover card kept rattling itself loose with my massive F U N K ! Quote Link to comment Share on other sites More sharing options...
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