Occasional popping sound - pictures and initial troubleshooting [resolved]

[Mike1590]

Hi all,

I’ve been loving my Crack ever since I completed the build a few months ago. I had some more consistent crackling/popping a little while back but have since addressed that through some additional soldering work. However, lately I have also noticed some very occasional popping noises in just the left earphone. Generally it’s so slight that I don’t notice it when listening to music anyway. The only time the issue presents itself to me is when I’m listening to a podcast, am between songs, etc. I have noticed that when I jiggle the small 12AU7 bulb around, the popping occurs, so I think I’ve largely been able to narrow down the issue to some soldering around that connector. I have tried taking some photos of the existing solder work around there, as well as around the headphone jack. Since the problem seems to be exclusive to the left earphone, I wasn’t 100% sure my issue didn’t lie with my soldering around that component instead. However, as stated before, the crackling sound becomes routine when the small bulb is messed with during playback.

Any help would be greatly appreciated! I’d be happy to try to take more pictures of specific soldering joints, as needed.

EDIT: Photos

[Paul Birkeland]

The junction of the 2.49K resistor and white wire on the headphone jack is suspect, as is the solder joint at A6.

Be sure to use leaded rosin core solder with your iron turned all the way up if it's adjustable.

[Doc B.]

I'd suggest touching up A1 as well.

[Mike1590]

Thanks guys! I’ll work on these tonight and report back. Appreciate the quick and thorough responses as always. Y’all are awesome!

[2wo]

And while you're at it, give the tube pins a good cleaning...John

[Mike1590]

After a bit of soldering work, I think I inadvertently made my problem a bit worse. Now there is a constant very low buzz sound. I suspect the problem is with my LEDs... I think both are too tight, first of all, as it requires some elbow grease to insert the 12AU7 bulb - I'm not sure if this is normal. There doesn't seem to be a lot of extra slack or bend in the leads to allow for flexing. Additionally, and more importantly, one of the leads was not soldered well. Due to the clutter of other wires, I had an extremely difficult time trying to get one of the leads through the hole in the pin. I am not confident in either LED connection, to be honest, and may need to try getting replacement LEDs and trying to start over. Would any of my issues possibly be indicative of bad solders with the LEDs?

Thanks!

[Paul Birkeland]

If your voltages are correct and the LEDs are illuminated, then that is not the issue.  People like to focus on the LEDs sometimes for whatever reason, and resoldering them and moving them around a lot will eventually break them. 

With some inexpensive, disposable headphones plugged into the Crack, poke around in the circuit with a wooden chopstick to see if anything you touch specifically can change the nature of the noise, then that will give you some guidance on what may be loose.

[Mike1590]

Paul, thanks again for the tips. I’ve actually read similar posts by you on other threads re: the chopstick prodding. Unfortunately, I can’t find a compatible pair of cheap headphones around the house I can use.

I contacted Doc late last night about sending my unit in for repair. I’m kinda worried now that I may be chasing my tail and “fixing” things (actually making more of a mess) that don’t need to be addressed. I think at this point I’d rather pay the penalty and have you all clean it up, since you actually know what you’re doing. I couldn’t find an option to submit a repair order last night on the website, so I don’t know if that’s something you’d be able to get going.

I also asked Doc if you’d be able to install my speedball attachment, as well, if I sent that in with my stock Crack unit. I’d expect an extra charge, I’d rather just not have to send my amp in a second time when I inadvertently screw something up with that, as well! 

[Paul Birkeland]

Just plug any cheap headphone in, they can be 16 ohms, that doesn't matter.

I would put a little more effort in before you throw in the towel and potentially spend a few hundred dollars for me to possibly only find one flaky solder joint.

[Mike1590]

I actually just found another headphone adapter that supports my wired earbuds, so I will go through those efforts later today and see what I can find out.

In other news, I just got a little jolt of electricity, I think around the headphone jack maybe. I didn’t do much around here last night, besides add a tiny bit of solder to one joint. I think what may have happened was that I was using a threaded adapter with my earbuds before (which wasn’t working) and maybe some juice came out since that connection wasn’t happening? I don’t know if that tracks or makes much sense or whether I have a new issue cropping up now… either way, I feel a bit more optimistic now that I’ve found some test headphones to play around with. I plan on tinkering with it a bit later this afternoon, so I’ll report back with my findings.

I said it before, but thanks so much for the encouragement/troubleshooting advice! Much appreciated!

[Doc B.]

Black wire at the headphone jack.

[Paul Birkeland]

Now that you mention it, where the black wires meet on the headphone jack you have a black wire that's not captured by solder.  This is a pretty common issue that I see on at least half of the Cracks that I receive for repair.

[Mike1590]

Update - trying to troubleshoot by prodding around with a chopstick is proving to be difficult. There’s a pretty regular crackling sound, so there isn’t an obvious indication when I poke at a joint with the chopstick if it’s eliciting a popping sound or if the noise is coming from elsewhere. I did touch up that black wire connection at the headphone jack. And I’ve isolated the crackling to just the left earpiece - would this help narrow down the possibilities of where I may need to check the solder joint? Both LEDs glow, so I’m not sure if that rules out those being the source of my issue or not… I’m going to review the instruction manual in the meantime here and double check my work around that smaller ocular socket.

[Paul Birkeland]

This is the wire that's not soldered.

[Mike1590]

Yeah, that’s the one I thought I touched up - I’ll double check. I just prodded the smaller tube while watching the LEDs/with headphones on. I heard a popping sound, almost like a relief sound and I noticed one of my LEDs go dark. The humming/popping sound also seemed to cease at this time. After maybe 5-10 seconds, that LED lit back up.