Rockhorst Posted May 4, 2009 Report Share Posted May 4, 2009 First off: I know I'm asking a lot of questions lately. Apologies, I don't mean to flood the board. Secondly: I replaced the pots for the bridge pickup in a friends guitar (Epi LP) a while ago. He has an EMG setup. I used the correct type of pots (25K, for actives). When I installed it everything sounded as expected. However he informed me the other day that the output from his bridge pickup was deteriorating. At the moment, it's almost gone. His neck PU still works fine. I checked the control cavity: all connections still there and solid, no continuity issues. Pots still rate as they should and show a nice smooth curve from 0 to 25K. Switch connections still work properly as well. Frankly, I'm clueless (again). Any suggestions or diagnostics I could run? It seems a stretch that the pickup would've broken down... [and yes, we have checked the battery ) Quote Link to comment Share on other sites More sharing options...
Rockhorst Posted May 4, 2009 Author Report Share Posted May 4, 2009 Some additional info: took the pickups out and checked them. Both show comparable resistance measurements and both are supplied with power from the battery. Bridge pickup also sounds a lot softer then neck pickup when no battery is attached. Quote Link to comment Share on other sites More sharing options...
Keegan Posted May 4, 2009 Report Share Posted May 4, 2009 If you want to be sure it's the pickup, you can hook it up directly to the jack and test it. Is it still under warranty? Quote Link to comment Share on other sites More sharing options...
Thoughtless 7 Posted May 5, 2009 Report Share Posted May 5, 2009 You tried changing the battery, just in case? Quote Link to comment Share on other sites More sharing options...
wood is good Posted May 5, 2009 Report Share Posted May 5, 2009 You tried changing the battery, just in case? He said he did in the original post. You should check the lug on the switch. Maybe its not getting thru to the switch. Quote Link to comment Share on other sites More sharing options...
Rockhorst Posted May 6, 2009 Author Report Share Posted May 6, 2009 Checked the connections to the switch and they seem to be in order. I think it's strange that there's a little bit of signal coming from the bridge PU instead of it being dead silent. I'm seriously thinking of desoldering the whole thing and going over it again... Quote Link to comment Share on other sites More sharing options...
psw Posted May 6, 2009 Report Share Posted May 6, 2009 A bit of a mystery if it worked and now is not...and not that familiar with EMG's...for instance, can an EMG function in anyway without a battery? My first port of call (after the battery thing of course) would be to suspect the jack plug switch. I assume it is wired so that when the jack plug is removed it turns off power. Also, stepping on the lead or poor connections, stray shielding shorting by the jack socket rotating, etc...are all easily done by a user, where as internal problems are pretty rare (unless you have poor wiring or shielding/shorting precautions and something can move inside the guitar). So...I could see that something in the switching might cut or short power so as to stop the EMG preamp getting power yet perhaps still pass a signal. If both pickups are not similarly effected (ie the neck pickup works fine but the bridge is faulty) then that might be another story. Checking each pickup separately and using a multimeter to detect the battery voltages and grounds may well be in order. perhaps that helps or provides some direction...hope so... pete Quote Link to comment Share on other sites More sharing options...
Rockhorst Posted May 6, 2009 Author Report Share Posted May 6, 2009 A bit of a mystery if it worked and now is not...and not that familiar with EMG's...for instance, can an EMG function in anyway without a battery? Yup. Signal is weaker and less defined, but they would still pass signal. I also checked the battery power: both pickups had a functioning power line. I'll recheck the switch and the jack. The switch was kind of a bitch to reinstall, so something might get busted there that got worse by some more swichting during playing. Will keep you posted. Quote Link to comment Share on other sites More sharing options...
mikke Posted May 6, 2009 Report Share Posted May 6, 2009 Maybe some of the components in the emg preamp are dead? Quote Link to comment Share on other sites More sharing options...
Keegan Posted May 6, 2009 Report Share Posted May 6, 2009 Maybe some of the components in the emg preamp are dead? That's what I'm thinking. It sounds like a failing component. Like a resistor losing its resistance to ground. He said it shows plenty of resistance though, so maybe it's a transistor or something, but then you'd think that the volume would be the same as before with the battery unplugged... Quote Link to comment Share on other sites More sharing options...
westhemann Posted May 6, 2009 Report Share Posted May 6, 2009 No I imagine it is a poor connection somewhere...you also may have heated the woven wire ground too much and burned through the pickups hot wire(the white one) If you burn through the white insulation on that wire it kills everything.EMG wiring requires a bit more finesse than passives. In any case,what you describe sounds exactly like a weak or dead battery,but in effect any kind of bad connection can cause it... Also...you did not solder the ground to the bridge,correct?because in some cases that also causes the same thing...EMG is not meant to be grounded to bridge,rather everything is grounded to the back of the volume pot,then run to the input jack... ALSO...take the pickup out and flip the plug over(on the bottom of the pickup)...if that is upside down they will not work. Quote Link to comment Share on other sites More sharing options...
Rockhorst Posted May 6, 2009 Author Report Share Posted May 6, 2009 Thanks Westheman. The thing you remarked that did make sense in the current situation is about the woven ground. That could be the case and could also initially still work and later on make a bad connection when the instrument gets a blow from for instance putting it down. I'll look into that. Quote Link to comment Share on other sites More sharing options...
westhemann Posted May 11, 2009 Report Share Posted May 11, 2009 update?get it fingered out? Quote Link to comment Share on other sites More sharing options...
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