Need help with GE-7 Mod (pops & crackles)

[bbmonster]

Hi All, hoping I can get some insight to my mess up. I attempted the GE-7 Hi-Fi mod from the post http://www.diystompboxes.com/smfforum/index.php?topic=51583.0 and now i get intermittent pops and crackles. Sounds like a camp fire where the wood crackles and then eventual pops, and the sound kind of goes up and down also, kind of cyclical.

I replaced the opamps to NE5532's and that was great. That reduced the irritating hiss down tremendously. Then I got greedy and wanted more, so I tried the capacitor replacements. Is there a problem with the capacitors I used? I used the following caps (description off the digi-key invoice, except for the .1uf which was from parts-express):

CAP FLM 1UF 63V POLY MKT RAD
CAP .68UF 10% 63V METAL POLY
CAP POLYFILM BOX .33UF 63V 5%
CAP .15UF 50V STACK METAL FILM
0.10uF 100V Polyester Film Capacitor

Thanks.
-Bernard

[R.G.]

Cold solder joints, from the description.

[rpjones]

yeah, I did the sniper mod to my GE7 and had the same problems. Turned out to be a bad solder joint. Just reflow your joints carefully and you should be good.

[WLS]

Did you clean your board after soldering?

Flux residue will cause all kinds of intermitting pops and crackles.

Bill

[bbmonster]

Thanks, I just re-soldered the caps and the campfire popping crackling noise went away. But now it sounds like a low pitched snow storm with a constant wind (still a bit more tolerable than the stock GE-7 Hissssssss). Is that normal? Or is that still a symptom of a cold solder?

[bbmonster]

Found the post http://www.diystompboxes.com/smfforum/index.php?topic=66402.0 that has what may be causing the wind like noise.

Yay, I learned what a cold solder sounds like. I also learned what a bad capacitor and/or opamp sounds like (booooo, that I gotta find them now in the circuit and hear the wife complain about the popping noises as I poke the debugging audio probe around).

[bbmonster]

A few more question because my success was short lived. I ended up changing all the capacitors I put in and the mod was a success. Super quiet, could hardly tell the unit was on. So I played my guitar with it for awhile, then before I put the GE-7 away I wanted to marvel at how quiet it was again and up each band individually to compare to how it was before. I lowered all the bands to the lowest settings and upped the lowest band to the highest setting, the windy noise came back. I'm guessing the capacitor or caps went bad again.

So my questions are, did a no-no with EQ's, lower all bands to the lowest settings then boosting up each band individually to the highest setting?
Are the capacitor voltage ratings too low (caps i used are in the first post, mostly 63V)?
Did I just happen to get a bad batch of capacitors?

Thanks.

[WLS]

63 volts should be able to handle just about anything we build unless you have something that would be generating that much voltage like a charge pump, but this is not the case. I would look into the resistor end of it stressing out a capacitor.

You should be able to put your settings anywhere you like without any consideration as to it's effect.


Bill