Kennerz Posted November 25, 2009 Share Posted November 25, 2009 Hello! I feel a bit odd being a Guitarist posting on a Bassist forum, but here goes Basicly, the Bassist in my band's amp went dodgy the other week. We had finished practicing and it started making an odd Lo-Fi noise and sevearly reducing the volume. No dials were knocked and it even did it when we took the cable out of the bass and pressed it. Dont know if this is enough description for any help but give me your best shot! Thanks Kennerz Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted November 25, 2009 Share Posted November 25, 2009 Would guess a dud speaker. See if there is a way to run a seperate cab from it. Figure if the issue is amp or speaker. Quote Link to comment Share on other sites More sharing options...
Kennerz Posted November 26, 2009 Author Share Posted November 26, 2009 Im guessing its a speaker because its a Marshall combo. Its stopped dooing it for a bit the other day but has started messing up again now Quote Link to comment Share on other sites More sharing options...
BOD2 Posted November 26, 2009 Share Posted November 26, 2009 What model of combo ? Are there any valves in the combo ? If so then checking the valves would be a good first step. Also check all the connections - speaker connections, mains cable. Try a different mains cable if you can or if the mains cable is hard wired then open up the 13Amp mains plug and make sure there are no loose wires in there (if you're not sure what you're doing inside a mains plug then get someone who knows about these things to check it). Quote Link to comment Share on other sites More sharing options...
Kennerz Posted November 26, 2009 Author Share Posted November 26, 2009 Its the Marshall MB4210. I think it has 1 preamp Valve. I shall have a look at it and fiddle with some of the stuff in it. I thought it could have been a broken input jack but i dont know if it would make the Lo-Fi noice, mabye more of a crackle. Thanks BOD2 Quote Link to comment Share on other sites More sharing options...
Al Heeley Posted November 26, 2009 Share Posted November 26, 2009 (edited) My MB4210 did [b][u]exactly[/u][/b] this about 2 months ago. I took the crossover card out from the speaker cab, the bit that divides the signal between the horn and the 10" speakers (you have to take the plastic carry handles off to access insode the cab) and found the big white fuse block had come loose where the legs are soldered to the PCB. It was a bad joint. 5 minutes reinforcing with some solder and a soldering iron and it was fine again. As I have reported on here before my crossover card on the MB115 extn cab had a very similar problem too - this time it was the inductor coil block that had come loose - bad soldering, tut tut. I got marshall to send me a replacement, it's been fine (so far) ever since. Edited November 26, 2009 by Al Heeley Quote Link to comment Share on other sites More sharing options...
Kennerz Posted November 27, 2009 Author Share Posted November 27, 2009 Thanks alot Al Heeley! I shall have a look inside it today! Shouldnt be too much of a job id think Quote Link to comment Share on other sites More sharing options...
Al Heeley Posted November 27, 2009 Share Posted November 27, 2009 (edited) [quote name='Kennerz' post='667120' date='Nov 27 2009, 10:09 AM']Thanks alot Al Heeley! I shall have a look inside it today! Shouldnt be too much of a job id think [/quote] While you have the crossover card out, just check the inductor coil connections too - I secured mine more with some more epoxy and a second secure cable-tie to hold it really firm onto the card. In my view thiis is a bit of poor design - a really simple little issue that is easy to prevent yet renders a whole amp/cab potentially useless. - Oh I guess I have to mention, this may void your warranty, but I think Marshall guys are pretty understanding. Edited November 27, 2009 by Al Heeley Quote Link to comment Share on other sites More sharing options...
Al Heeley Posted November 29, 2009 Share Posted November 29, 2009 Exactly the same thing happened again at the giog last night, with the MB115 extension cab - low power and dreadful intermittant distorted sound. Took the crossover card out when I got home and found same white fuse block legs had loosened from the solder point onto the pcb. This is really disappointing sloppy QC from the Marshall factory - thats a spate of failures all on the crossover cards within 10 months of purchase. Quote Link to comment Share on other sites More sharing options...
thinman Posted November 29, 2009 Share Posted November 29, 2009 [quote name='Al Heeley' post='668953' date='Nov 29 2009, 10:31 AM']Exactly the same thing happened again at the giog last night, with the MB115 extension cab - low power and dreadful intermittant distorted sound. Took the crossover card out when I got home and found same white fuse block legs had loosened from the solder point onto the pcb. This is really disappointing sloppy QC from the Marshall factory - thats a spate of failures all on the crossover cards within 10 months of purchase.[/quote] Solder joints can be prone to cracking - especially when there's a large component that might be subject to vibration. In a lot of guitar/bass amps large components like capacitors etc are often glued on with hot-melt glue and/or tied on with cable ties. I had a problem with an amp like that. I also had problems with a boiler control PCB that kept faiing for the same reason. Quote Link to comment Share on other sites More sharing options...
Al Heeley Posted November 29, 2009 Share Posted November 29, 2009 Being a bass amp, you'd expect a company with Marshall's heritage to be able to anticipate this sort of failure mode and take steps to prevent it. Disappointing such a small easy-fix issue can screw up a gig. Quote Link to comment Share on other sites More sharing options...
ColdShoulder Posted July 28, 2012 Share Posted July 28, 2012 Yes, had to re-solder a capacity a few weeks back in a 15" marshall cab. Annoying. Quote Link to comment Share on other sites More sharing options...
mcnach Posted July 29, 2012 Share Posted July 29, 2012 Quote Link to comment Share on other sites More sharing options...
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