Loud buzzing when plugged into crack

[lazyoliver]

Hello, I've had my crack with speedball for about 4 years now but while trying to fix a faint ringing in the left channel (which I believe was caused by a microphonic tube) I've ended up with a crack that only makes buzzing sound that's uncomfortably loud and occurs with the volume pot all the way down.

To fix the ringing problem I purchased a 12BH7 to replace the microphonic 12AU7 I've been using. When I put in the new tube and turned the crack on I thought I had fixed the problem and the crack sounded as great as always for the first minute. After that first minute though, white noise started to crescendo in the right channel and I turned the amp off. I went back to the 12AU7 hoping it was something related to the 12BH7 but no luck, the white noise was still there. I then proceeded to clean the tubes and their sockets as well as reflow the solder joints for the right channel. The white noise remained. I then noticed the speedball boards where a little dirty from flux and I then cleaned that off with some rubbing alcohol and then tried turning the amp on one more time. Now as soon as the headphone makes contact in the headphone jack I get a loud buzzing sound.

I've double checked my wiring for shorts or cold solder joints but nothing sticks out and I'm not sure where to go from here. Does anyone have any ideas?

[Doc B.]

A loud buzz is usually caused by a bad ground connection. So check the black wire connections, particularly the ones on the headphone jack. Also make sure all of the filter capacitors are well connected.

[Paul Birkeland]

What kind of soldering products did you use on the build?

[lazyoliver]

Thank you for the replies. I gave everything another go over reflowing the solder joints for the filters caps and headphone jack and tried to clean up some excess solder. Now the buzzing is gone but the whitenoise/TV static is still present in the right channel. When I turn the amp on its good for ~30 secs then the noise fades in and then ~30 secs it fades out. I let it sit running for 15 mins with nothing to connected to the amp and then took another listen and the noise was back and didn't go away again. Paul, I used the same 60/40 I've used on all my projects and never had a problem with and a Hakko fx-888D iron.

[Paul Birkeland]

On the FX888, it's very easy to accidentally adjust the temperature calibration when you think you're turning the tip temperature up.  This can leave you with an iron that says 899 degrees but with a tip temp that's far lower than that, then you end up with lots of cold joints.  I went through this when I first got my FX888, and I had to go through the procedure to do a factory reset, then use the not so intuitive method to properly adjust the tip temperature.  Since I see joints in this amp that aren't well flowed out, this is something to look into.