Popping when inserting headphone jack

[RestoredSparda]

Finished a new build. Double checked and reordered all points going to the headphone jack as I've had this popping issue before.

I'm getting a mild popping in headphones when the middle and last ring on the TRS jack make connection and am inserting the headphone jack while the amp is on.

The mild popping occurs when removing the jack and inserting while amp is on. The popping volume is louder if volume isn't set to minimum.

My question. After going over this amp with a fine tooth comb, is some mild popping when inserting a headphone jack normal for the Crack circuit, or do I need to do some more troubleshooting?

No.other issues, all resistance and voltages passed. No noise when tapping on chassis while headphone is plugged in and Amp is on.  No noise when headphone is connevted and amp is turned off.  Normal startup noise when Amp is turned on. Etc.

Thanks for the help!

[Doc B.]

Reflow all of the terminals on the headphone jack and see if that helps.

[RestoredSparda]

Thanks. No change after resoldering.

I also inserted an adapter 1/4 inch to 3.5mm, so I could rule out moving joints as the culprit (I think). With the adapter. I still get mild pops in headphone when inserting the 3.5mm end into the 1/4 adapter. 

[Paul Birkeland]

99% of the time this happens because one of the black wires that connects to the headphone jack is not captured by solder.

[RestoredSparda]

Thanks Paul. I went over the entire build step by step and everything looks correct and solid.

I am going to pull out the headphone jack completely and rewire with a spare. Can't think of anything else to mess with.

[RestoredSparda]

Thanks for keeping me on track guys. I reflowed all the headphone jack terminals for the 3rd time this time at a higher heat and really let em get hot.

I also at the same time removed the aftermarket output caps and reverted to stock. 

Pops are gone. Time to see if the caps were the issue and put them back.  Thanks again for steering me to the correct path.

[RestoredSparda]

Turns out to be the Russian output caps. After reinstalling the mild pops are back. Perhaps the higher voltage rating or they are just bad? Very old caps. Anyways the mystery is solved.