kodiakblair Posted September 29, 2016 Share Posted September 29, 2016 (edited) Picked up this Laney monitor for the princely sum of £10 a few weeks back and hoping for some tips on reducing the hum. Starts as soon as you power up and really only changes when the bass is turned up. It's constant whether there's anything plugged in or not. XLR makes no difference either. Doesn't appear to get louder when you turn the volume up full. I know very little about amps so any pointers will be welcome. Cheers KB Edited September 29, 2016 by kodiakblair Quote Link to comment Share on other sites More sharing options...
morgano Posted September 29, 2016 Share Posted September 29, 2016 It could be faulty capacitors in the power supply. Quote Link to comment Share on other sites More sharing options...
kodiakblair Posted September 29, 2016 Author Share Posted September 29, 2016 Thanks @morgano Just been doing a Google search and that gets mentioned quite often. Hope it's not difficult to test for and fix. Quote Link to comment Share on other sites More sharing options...
kodiakblair Posted September 29, 2016 Author Share Posted September 29, 2016 Good Call @morgano Armed with the knowledge that costing me £10 it was no biggie if I messed up I Googled "faulty power supply capacitors" They don't appear blown or burst,certainly no bulge, they did however move when prodded with the pliers handles. Gave a push till the hum stopped then fixed them in place. Result Quote Link to comment Share on other sites More sharing options...
morgano Posted September 30, 2016 Share Posted September 30, 2016 (edited) Hmm. You might find it comes back. Possibly is a dry joint that is taking one or more of the capacitors out if the circuit. By moving it you've (temporarily) re-made the connection. If it comes back or you fancy a bit of soldering it might be a good idea to resolder their connections on the PCB. Edited September 30, 2016 by morgano Quote Link to comment Share on other sites More sharing options...
MoonBassAlpha Posted September 30, 2016 Share Posted September 30, 2016 Yes, this is quite a common thing with capacitors. Being larger components, there is more mass to resonate, and usually being supported by the soldered joints alone, are prone to annular fractures around the legs. This can cause crackles as well as hum as the capacitor connects and disconnects. These large components are often supported using hot glue, but I find the adhesion to circuit boards fails with time. When reworking these components, I prefer to use silicone rubber sealant, then reflow the solder joints. Quote Link to comment Share on other sites More sharing options...
kodiakblair Posted September 30, 2016 Author Share Posted September 30, 2016 @MoonBassAlpha That's exactly what happened.They'd come away from the hot glue so I cut nylon jams and fixed them in place with Mitre Mate. Quote Link to comment Share on other sites More sharing options...
morgano Posted September 30, 2016 Share Posted September 30, 2016 Yes, now you've fixed them mechanically, it would make sense to reflow the solder joints for a long term fix. Quote Link to comment Share on other sites More sharing options...
kodiakblair Posted September 30, 2016 Author Share Posted September 30, 2016 That'll be definitely be next. Makes sense as if they moved once it'll happen again. Thanks for your input folks. Quote Link to comment Share on other sites More sharing options...
MoonBassAlpha Posted October 1, 2016 Share Posted October 1, 2016 You're most welcome. It's a good feeling to get to the bottom of the problem and not just give it a whack and hope it's going to be ok. Quote Link to comment Share on other sites More sharing options...
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