daz Posted July 16, 2010 Share Posted July 16, 2010 (edited) My Behringer combo has been intermittantly cutting out for several seconds then coming back on again. At first i thought it was the lead, but it happened with a new lead too, then i noticed the VU meter still bouncing up and down as i strummed noiselessly, so it cant be lead problems. Any thoughts on why its happening? ps. Its about 18 months old and has had very light use. Still had the labels on and not a mark on it when i got it for a song on ebay. Edited July 17, 2010 by daz Quote Link to comment Share on other sites More sharing options...
escholl Posted July 17, 2010 Share Posted July 17, 2010 protection circuitry coming on maybe? either that, or it's probably a dry joint or loose connection somewhere in the amp. Quote Link to comment Share on other sites More sharing options...
daz Posted July 17, 2010 Author Share Posted July 17, 2010 I have just realized this only seems to happen after its switched on for 30 minutes or so and never before.? Quote Link to comment Share on other sites More sharing options...
escholl Posted July 17, 2010 Share Posted July 17, 2010 [quote name='daz' post='897362' date='Jul 17 2010, 03:44 PM']I have just realized this only seems to happen after its switched on for 30 minutes or so and never before.?[/quote] That sounds like it could be a dry joint then. I don't know if you're handy with a soldering iron, but if you are it should be fairly easy to spot if you look at the underside of the PCB, and a quick fix. Quote Link to comment Share on other sites More sharing options...
daz Posted July 17, 2010 Author Share Posted July 17, 2010 so i'm looking for a crack or gap in the solder somewhere? Quote Link to comment Share on other sites More sharing options...
Daquifsta Posted July 17, 2010 Share Posted July 17, 2010 That, or a joint where the solder is dull and grey, rather than silver and shiny. Quote Link to comment Share on other sites More sharing options...
escholl Posted July 17, 2010 Share Posted July 17, 2010 Yes, hopefully it will be obvious, as it sometimes is quite obvious, but other times it will be nearly invisible to the naked eye and you will just have to re-flow any solder connections that look questionable. Attached image should show roughly what it looks like, although that is a particularly bad example and you issue may not be as obvious. There is also, of course, the chance that it is not a dry joint at all but something completely different. Quote Link to comment Share on other sites More sharing options...
thinman Posted July 17, 2010 Share Posted July 17, 2010 [quote name='escholl' post='897534' date='Jul 17 2010, 07:50 PM']Yes, hopefully it will be obvious, as it sometimes is quite obvious, but other times it will be nearly invisible to the naked eye and you will just have to re-flow any solder connections that look questionable. Attached image should show roughly what it looks like, although that is a particularly bad example and you issue may not be as obvious. There is also, of course, the chance that it is not a dry joint at all but something completely different. [/quote] That sort of cracking around joints is very common - especially on large components or anything subject to any vibration and not firmly fixed. I had it on the joints to the pots of the tone and volume controls of one of my heads (so much for superior German engineering!) - the pots were mounted to the front panel but the board they were mounted on had a bit of flex in it. The result was cracklng and cutting out. Easily fixed with the soldering iron (and more fixings!). I also had exactly the same problem wih a boiler control PCB. Useless for bass anyway. As stated above, they are dificult to see. A bright light and magnifying glass help. Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted July 20, 2010 Share Posted July 20, 2010 You might find this useful [url="http://www.ultimate-guitar.com/columns/gear_maintenance/a_guide_to_fixing_intermittent_faults.html"]http://www.ultimate-guitar.com/columns/gea...ent_faults.html[/url] Quote Link to comment Share on other sites More sharing options...
Subthumper Posted July 20, 2010 Share Posted July 20, 2010 (edited) Hi, I repair alot of amps that have this soldering problem and have noticed it being quite common on a lot of newer amps and equipment that use lead free solder. It seems to be much more brittle and from having done production work with it it is a lot more difficult to make the solder in a joint flow due to the temperature required. I usually reflow these with leaded solder. As mentioned its quite common on larger components and any that are under physical load, inparticular input, output, FX and mains sockets. DONT FORGET TO UNPLUG IT WHEN YOU TAKE IT TO BITS. I know this by experience. Good luck finding the fault. If your not sure what your doing go to a proper tech. Cheers Just Edited July 20, 2010 by Subthumper Quote Link to comment Share on other sites More sharing options...
daz Posted May 4, 2011 Author Share Posted May 4, 2011 (edited) Nearly 9 months later speedy daz finally gets around to having a look see at the old dry joint problem. Thing is, after 5 minutes with a screwdriver now i am stuck on how to get the damn amp out of the top of the cab. I have taken out all the marked screws (see pic) Then after prising the side wings from the front I assumed it would push out from the rear. No joy though, and i cant see any more relevant screws. Anyone got any ideas to aid me ? (apart from the obvious "get a decent make of kit" Hey i only paid £70 for it) [attachment=79046:behringer_cab.jpg] Edited May 4, 2011 by daz Quote Link to comment Share on other sites More sharing options...
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