Loud Hum after soldering loose joint

[grantr2]

I finally got a chance to solder a loose connection to the volume knob which was causing popping and crackling. After doing so, I now notice a loud humming noise out of the right channel of my headphones. Any idea what could be the cause of this? I have attached some images, but please let me know if more are needed.

I purchased this BHC second hand with upgrades (speed ball, 24 step attenuator, film caps, upgraded power cable), but not sure if these are contributing to the issues.

Thank you

 

[Paul Birkeland]

You'd want to double check that the DC voltages are in-spec before using an amp that isn't appearing to work properly.

I think you might just be battling with a flaky solder joint that needs more heat. With all the extra caps stuffed in there, it might be hard to get to some of them.

-PB

 

[grantr2]

Thank you for your response. What is the process for checking the DC voltages are in spec? Not sure if it matters, but before I soldered the loose wire, sound was coming out of the unit fine, but would have the occasional pop up crackling, which I believe was caused by the loose wire on the attenuator volume knob.

What’s the easiest way to tell if the solder joint I just did has enough heat? What is the recommended temperature to use? I was at 375 degrees when I solder the loose connection. Thank you again for your help.

 

[Jameson]

Take a look at the manual. There are resistance and voltage checks after the build instructions. Running those tests can help identify where there are issues. If everything comes back within spec, the next step would be to plug in a pair of cheap headphones and poke around with something non-conductive (like a wooden chopstick) to see if you can reproduce the crackle at a certain joint.

We recommend turning the iron all the way up. 375 F is not nearly hot enough. 375 C is probably fine.

 

[Doc B]

If the hum started after you soldered some terminals it would probably make sense to see if a wire came loose from a connection that was weak and got disturbed when you were working on those terminals. A loud buzzy hum is most often due to a bad/loose ground connection. A lot of those joints look like they could use a little more solder to get them to where they have a nice even fillet of solder between the wire and the connecting point.