DanOwens Posted March 16, 2008 Share Posted March 16, 2008 Hey peeps, I have a reasonably cheap little vocal PA that I also use for amplifying my students. Problem is, when I moved into my new house it seems to have gained a bit of a problem in that it all works fine until I tap my foot on the floor a little too hard, or knock the table it's on lightly. When this happens, it cuts out for about 10 seconds then comes back on again. As such I've only been using it in my teaching room and I'd like to use it with my groups too. I'll take it apart and have a look, assuming something has got knocked in transit and I have only to push it in a little. Any ideas before I dis-mantle the thing??? Thanks peeps!!! Dan Quote Link to comment Share on other sites More sharing options...
BOD2 Posted March 16, 2008 Share Posted March 16, 2008 It pretty much sounds like a loose connection somewhere. Check any the external cables first before you open anything up - could it be a loose connection in the mains plug, or a loose speaker wire connection ? Are there any external fuses anywhere ? If so check that these aren't loose. Quote Link to comment Share on other sites More sharing options...
DanOwens Posted March 16, 2008 Author Share Posted March 16, 2008 Ta BOD. Figured 'loose connection' just wondering why it comes back on after a specific amount of time, rather than until I next hit it, you know? Dan Quote Link to comment Share on other sites More sharing options...
BOD2 Posted March 16, 2008 Share Posted March 16, 2008 Unless it has some kind of "limiter" built-in to prevent overload. A loose connection might be triggering the limiter somehow and the limiter might have a "reset time" of 10 seconds ? (just guessing, I'm afraid). Quote Link to comment Share on other sites More sharing options...
DanOwens Posted March 16, 2008 Author Share Posted March 16, 2008 I thought something similar. Maybe there was some kind of trip-switch if there was a power spike designed to cut rather than put out a massive square-wave and tear everything to shreds? Again, just guess-work. Dan Quote Link to comment Share on other sites More sharing options...
warwickhunt Posted March 16, 2008 Share Posted March 16, 2008 [quote name='TheBrokenDoor' post='158640' date='Mar 16 2008, 10:11 PM']I thought something similar. Maybe there was some kind of trip-switch if there was a power spike designed to cut rather than put out a massive square-wave and tear everything to shreds? Again, just guess-work. Dan[/quote] Cheapie PA heads don't tend to have such niceties as trip switches etc. As you've said vibration points to something loose but time delayed return tends to indicate circuitry problems could be solder joint... could be a million things TBH. I think you'll have to bite the bullet and put it in for repair! Quote Link to comment Share on other sites More sharing options...
DanOwens Posted March 17, 2008 Author Share Posted March 17, 2008 [quote name='warwickhunt' post='158680' date='Mar 16 2008, 10:59 PM']put it in for repair![/quote] More like pull it to bits with a soldering iron at the ready!!!! I'm one of those guys!! Dan Quote Link to comment Share on other sites More sharing options...
thinman Posted March 17, 2008 Share Posted March 17, 2008 [quote name='TheBrokenDoor' post='158795' date='Mar 17 2008, 09:42 AM']More like pull it to bits with a soldering iron at the ready!!!! I'm one of those guys!! Dan[/quote] Check all the obvious stuff first - I had a long standing problem with an amp crackling and cutting out. Turned out to be the mains fuse in the 13A plug had disintegrated but was still passing current somehow. The intermittent nature could be some joint or even component cooling and making enough contact again after disturbance. Check any PCB joints of large-ish components as the solder can suffer stress fractures due to vibration. Apart from amps things likes boiler control boards can suffer like this where vibration makes inadequately secured components vibrate and eventually cause a hairline fracture in the solder. [b]However, unless you're pretty confident about working on equipment such as this I'd suggest taking it to a pro as there are hazards with charge still knocking about in large capacitors.[/b] Quote Link to comment Share on other sites More sharing options...
DanOwens Posted March 17, 2008 Author Share Posted March 17, 2008 I should add that only the audio signal cuts out (the digital effect led stays lit), bookended by a very slight clicking sound, not unlike a switch!!!! Dan Quote Link to comment Share on other sites More sharing options...
Huge Hands Posted March 17, 2008 Share Posted March 17, 2008 (edited) [quote name='TheBrokenDoor' post='159239' date='Mar 17 2008, 09:33 PM']I should add that only the audio signal cuts out (the digital effect led stays lit), bookended by a very slight clicking sound, not unlike a switch!!!! Dan[/quote] Beginning to sound like a relay to me. Either the relay is bad, or the circuit switching it is. Unless you have electronics fiddling experience, I'd get it into a shop for repair. Edited March 17, 2008 by Huge Hands Quote Link to comment Share on other sites More sharing options...
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