Non-bypass pop

[mcasey1]

I just recently completed an AMZ Splitter-Buffer, and I am getting a steady pop every 3 to 4 seconds or so.  Not incredibly loud at first, but it becomes loud enough to be an annoyance.  Turning down guitar volume does not affect the popping.  The circuit has a common input stage that feeds three buffers, and no matter which buffer output of the 3 I connect to my amp, I get the popping noise.  So I figure it is somewhere in the power area that provides voltage to all buffers, or in the input area.  Any quick tricks (capacitor across power + - ?) that could diagnose or solve the problem?  I am going out on a limb and saying that it is a power situation.  Maybe some filtering with a large cap?  I'd love to hear your suggestions!

Thanks

Matt

[JDoyle]

Seeing as there is a 'timing' aspect of your problem, the '3 to 4 seconds', it means that one of the caps is charging up and then somehow discharging - it's the discharge that gives you the pop.

I'd say plug it all in, and use a multimeter to measure the voltage on the caps, one (or more) will climb and then drop back down, that is the source of your problem.

You may want to go through the schem again and make sure that all of the caps are soldered in correctly, no solder bridges, etc.

Good luck!

Jay Doyle

[mcasey1]

Thanks so much!  I will do just that and report back.

Matt

[mcasey1]

Measuring across the electrolytic 1uf caps I get:

one goes from -5.45V to -5.65V 

one goes from -4.20V to -4.25V

another from -4V to -3.90V

The one with the -5V values is the closest buffer to the input, they are in order from left to right as per the layout here:

http://www.muzique.com/lab/splitter.htm

Are any of the voltages supposed to fluctuate between these values in the time of 3 to 4 seconds?  Obviously the first exhibits the most change, but should any of them show any change like this?  Thanks!

Matt

[Mark Hammer]

It's bonehead stupid, and maybe even a nuisance, but in the absence of obvious electronic indicators, I think the smartest thing to do is replace the first cap with a fresh one, listen for the pop, then move to the next one if no pop is heard.  Just make sure you don't damage with excessive heat in the process.

[mcasey1]

Thanks Mark!  That did the trick.  Splitting and buffing with no pop or noise!

Thanks again

Matt