IC Buffer and pop sounds

[denny99]

Hi all,
I bought General Guitar Gadget IC buffer PCB, get the components from a local shop and got the chance to assembled it during the weekend. I only omitted the 3PDT switch as I want the pedal to be always on (first pedal in my chain).
The buffer works great, but I have an annoying problem with a true bypass pedal which is placed right after the buffer. It's a distortion pedal (very well known brand) which pops loud when engaged with the switch. This pop sound don't occur when the buffer is removed from the pedal chain and the guitar is plugged directly into the distortion pedal.
I'm using a good regulated and filtered DC power supply to power my pedals.

Any suggestion?  

Thanks in advance,
Denny

[Toney]

Sounds like it could be DC leaking at the output of your buffer build, thats the first thing to check anyhow.
You can measure it simply with a multimeter set to a low range voltage across the output.

[denny99]

Sounds like it could be DC leaking at the output of your buffer build, thats the first thing to check anyhow.
You can measure it simply with a multimeter set to a low range voltage across the output.

thanks Toney, I just measured it and there is some leaking! admittedly I'm not an electronics expert
but what should I double check in the circuit to address the issue?

again, thanks
Denny

[Toney]

Well how about the orientation of the output cap?
Its an electro, so if its reversed or damaged that could be the culprit.

[denny99]

Thanks Toney,
yes it's an electrolytic. I double checked the polarity, and it's correct. I tried with a new cap but the problem persists. I even tried deliberately reversing the cap polarity and no changes: the loud pop sound is still there and so is the DC leaking...  

[merlinb]

The GGG IC buffer has no pull-down resistor on the output. Unless you added one (say 100k) this is probably the source of your popping.

[denny99]

The GGG IC buffer has no pull-down resistor on the output. Unless you added one (say 100k) this is probably the source of your popping.

I haven't added one. I now tried soldering a 1K resistor and the pop is gone :-) thanks!
I will get myself a 100K resistor as I don't have one at the moment.

[merlinb]

I will get myself a 100K resistor as I don't have one at the moment.

Anything in the 5k to 1M range should be fine!

[denny99]

Anything in the 5k to 1M range should be fine!

Thanks, will try!