Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: Mike1590 on October 13, 2022, 10:43:28 AM
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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
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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.
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I'd suggest touching up A1 as well.
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Thanks guys! I’ll work on these tonight and report back. Appreciate the quick and thorough responses as always. Y’all are awesome!
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And while you're at it, give the tube pins a good cleaning...John
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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!
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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.
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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. ;D 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! ;)
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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.
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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!
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Black wire at the headphone jack.
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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.
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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.
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This is the wire that's not soldered.
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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.
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The issue definitely seems to be in some way related to that smaller "A" socket. When I wiggle around that tube, I am getting the popping noises. Nothing happens when I move around the larger one. In any case, I took a few more pictures... which have made me realize just how messy my install is! :-[ pardon the melted wire insulation.
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What kind of solder did you use? There is a lot of excess flux on those joints.
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I used Cardas Quad Eutectic Solder with Rosin Core.
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Which LED goes out? What are your voltages when it goes out?
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Those are good questions, Paul. I can try to replicate the issue and measure it then. How should I measure the voltage when it goes out - where should be DVM leads go?
I think the LED that briefly went out was the one attached to A3... I'll verify if I'm able to replicate the issue tomorrow.
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Just let me know which LED is out and what the voltages are on terminals 1-5.
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10-4, I will report back tomorrow. Thanks again!
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I actually had a chance to check on these tonight. Lucky (maybe the wrong word) for me, the LED was already out before I started checking voltages. The problem LED is the one soldered onto pin A3. The issue appears to be with terminal 5. Here are my voltage readings now:
1. 81.2
2. 165.9
3. 0
4. 165.6
5. 148.5
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Measure the voltage at A3. If it's around 12V, the LED is damaged. A workaround for this is to connect a wire between A3 and A8 to restore operation.
If the voltage is 0V, that means the connection at A4/A5 isn't solid and needs more attention.
If it's something else, be sure to let us know.
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It’s measuring ~.89 V - so about 0. Would that imply needing to touch up A4/A5 then?
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Are both halves of the 12AU7 glowing? It is most likely that the solder joint at A4/A5 is loose.
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It looks like the tube is fully illuminated, but I do have the top of the chassis upside down while I’m working on the undercarriage, so I don’t have the best view. I touched up A4/A5, but terminal 5 is still reading ~150V. Any other thoughts where this extra voltage could be coming from? I’d also be happy to take a picture of A4/A5, but I’m pretty confident in that soldering now.
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Also, A3 is still measuring about 0.6V. So that would imply that the issue is still with A4/A5 based on one of your previous replies. I will provide a picture of those connections.
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What's the DC voltage at terminal A2?
The excess voltage is there because the tube isn't conducting.
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Ah, makes sense. Here is a new photo of the connections on that socket - specifically A4/A5 shown. I will check on the voltage of A2. Side note, what is all of that orange/brown stuff? I never noticed all of it until I started working on the underside of the chassis again recently. As far as I know it isn't affecting performance at all, just looks messy/dirty & I'd like to clean some of it off if possible. Unsure if it's excess solder that's fallen off my iron while working maybe?
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A2 is measuring 0V (0.6 mV, to be exact).
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The brown stuff is flux. If you've used rosin core solder, that's totally fine to see there and you can use alcohol and a toothbrush to remove it.
0V at A2, an unlit LED at A3 and 0V at A3 and high voltage at terminal 5 would normally point to the A4/5 solder joint, but you say you have both halves of the tube glowing and the solder joint looks OK.
If the 22.1K resistor between terminals 4 and 5 isn't well connected, that would cause this problem also, as would a loose wire between terminal 5 and A1. If you happened to break off the plastic guide pin on the 6080 and you inserted it in one specific way that's not correct, you could also end up with high voltage on terminal 5, but this also seems unlikely based on the information provided here.
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Ah sounds good. I will try to scrub some of that off once I get my amp working right again. I will check on those other connections tomorrow. You are correct that the 6080 guide pin is still in place, so I don't suspect that's the case either. I'll keep ya posted once I check on the connections you described and have had a chance to touch them up/re-measure voltage. I will also double check both halves of the tube are glowing by putting the chassis right-side up. Thanks again for your guidance on this!
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I couldn't wait to tinker til tomorrow, so I played around a bit more tonight. Good news! The A3 LED now glows and the voltage on terminal 5 has gone down. There is still a low and constant buzzing in both headphone earpieces, but I think I'm getting closer to finding a fix. I did try tapping around with a chopstick a bit and didn't hear the same popping that I was hearing before - but having said that, I didn't mess around for too long, so it's very possible those sounds still exist.
Terminal 5 - 82.4V
A3 - 1.578V
A2 - 0V
A1 - 81.9V
If you have any more thoughts, I'd love to hear 'em! Otherwise, I'll plan to test for the popping sound a bit more tomorrow and report back.
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For a low buzzing sound, I would check that all the 220uF capacitors are well connected and soldered to the terminal strips.
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That did the trick!!! No more buzz and now I can move that smaller tube all around during playback without any popping sounds. You’re the man, Paul! Thanks so much for walking me through everything.
Edit: And most importantly, thanks for giving me the confidence to keep tinkering before throwing in the towel (and a bunch of money).
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Darn, I jumped the gun. During music playback there was a loud pop and the left earphone completely cut out. At that time one half of the small tube also went out - presumably the one connected to A3 since that’s the one I’ve had trouble with. Should I try bypassing the LED and using a wire to bridge the pins like you suggested before?
Edit: I was able to confirm that the side of the tube that went out is the side connected to pin A3.
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If half of the tube stops glowing, it's not the LED.
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Ah okay. So should I just start by checking back through the locations we already discussed then? Any other possible culprits that weren’t mentioned earlier in this thread?
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The tube glows from AC voltage fed to it by the green twisted pair of wires. If one half of it stops glowing, the connection between A4 and A5 still isn't quite right.
You can remove all of the other wiring in the amplifier besides the green wires and the incoming AC wiring from the power switch and IEC module and the 12AU7 will still light up.
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Good to know. There is a tiny bit of solder on the white plastic socket between pins A4/A5. I’m wondering if that could be the cause of my problem? I tried to snag a photo of it but it’s nearly impossible to get an accurate looking shot of it. Is there a good way to try to clean that out without reheating the solder and trying to use a solder pump? As you’re aware, I don’t have a ton of real estate to work around in, so I don’t know how possible that attempt would be…
I may just try to suck as much solder out from A4/A5 pins and start that connection over again…
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A4 and A5 need to be connected, so if there's a speck of solder between them, that isn't hurting anything.
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Should I have the actual pins be soldered together? I had it configured this way before I started this troubleshooting process, but removed that solder a few days back. It looked like the pins were separate in the instructions, but since I originally had them soldered together, it makes me think I read that somewhere in the instructions while I was initially working on my build… either that or I just made a mistake, which is most likely! :)
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It's also possible that you have some dirty tube pins that are giving intermittent contact, and these can be cleaned by simply pressing the tube into a piece of steel wool a few times. There's a very remote chance that the 12AU7 has an intermittent internal connection, but this is extremely rare and typically comes up when we test the tubes prior to shipping.
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This was something else I was considering, so I’m glad you mentioned it. The tube that gave me issues this morning is one I bought secondhand online for tube rolling, NOT the one y’all had sent me in my kit. I will try my amp again with the tube Bottlehead included. I’ll also clean the pins on both tubes, just to be safe.
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I don't want to jinx it, but I think I may have found and fixed my issue. I was using a power cable from another amp that I was using while I worked on my Crack. That power cord sort of fit my Crack, so I didn't think anything of it at the time. But it was pretty loose. I ended up using the proper power cable that came with my Crack kit and it fit MUCH snugger. Since making that switch, I haven't had any issues and I'm now a couple hours into music playback. I also cleaned my tube pins for good measure, and am using the tubes that came with my Crack for now. So far so good! Fingers crossed! I'll probably send another follow-up in here later tonight after logging a few more listening hours while I work, but I am thinking this may be resolved!! ;D
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After ~5 hours or so of listening, I have had 0 issues with buzzing/popping. I think it’s probably safe (knock on wood) to mark this one as resolved. Thank you again so much for all of your guidance, Paul!
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Argh, this is the never-ending problem apparently! After hours of consistently excellent playback, this morning after another “pop†I lost all audio from the left channel. The small 12AU7 tube stayed illuminated completely, leading me to believe this is an LED problem. Based on an earlier comment from you, Paul, and some searching around, I suspect I’ll need to remove that A3 LED and jumper A3 and A8 with a wire. Super newbie question incoming, but does it matter which color wire that came with the kit I use, or are they all created equal? Thanks!
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White, black, or red would be a good idea. There are voltage issues that would come with a dead LED that would confirm this is the issue.
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Thanks for the quick response. What would be some troubling voltages to keep an eye out for - or are there too many possibilities to list them all? I tried powering on/off the amp a few times and was still not getting any audio out of the left channel, so I’m hoping the problem is constant enough to be replicated when I put my amp back on my work bench later tonight…
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What are the voltages on terminals 1-5 and A3?
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Based on your reply on page 2, I think my LED on A3 is no good. I think my voltages are in range off the top of my head, except for terminal 5 and A3 (which is right around 12 V):
1. 81.6 V
2. 166.6 V
3. 0 V
4. 166.1 V
5. 149.1 V
A3. 12.7 V
Also, I noted the following during testing. Prodding terminal 5 for the voltage check resulted in crackling in both channels (likely due to the high voltage? But maybe a sign of a bad solder joint). The A3 LED was dark. Still no sound in left channel, like earlier.
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Yes, that is a voltage that indicates a dead LED.
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10-4. Any recommendations re: length of wire, amount stripped back at each end, clip off the dead LED I assume, etc.?
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About 1-1/4" stripped 1/4" at each end should work.
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So the saga continues… :) I jumpered A3 and A8 and am now registering expected voltages at both socket pins. All of my other voltages measured at terminals 1-10 also appear to be in range:
1. 84.1V
2. 172.6V
3. 0V
4. 172.6V
5. 81.9V
6. 0V
7. 104.7V
8. 0V
9. 105.5V
10. 0V
A3. 1.59V
A8. 1.59V
However, I am still having some occasional loss of sound in my left channel. This isn’t a consistent loss of sound like I was experiencing prior to this jumpering. The only thing I can think of is that the LED lead connected to A8 doesn’t go through the pin. Rather, it was sitting on top of the pin and then I soldered it on. I was having an extremely difficult time getting both the LED lead and the jumper wire through that small hole. If that was the cause of my issue, I’d expect the right channel to be impacted, but my issue still seems to just be exclusive to that left channel… but I may be wrong about that…
Edit: To add to that comment, I’ve never seen the A8 LED go dark during voltage measurement when I have the undercarriage of the chassis exposed. Not that this would necessarily mean anything, but if it was responsible for loss of sound/power, I’d expect to see it flickering some. Again, not sure how accurate my line of thinking is though.
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Unfortunately we find that our customers really like to zero in on the LEDs when there's something amiss with a Crack kit, and often they will poke, prod, and resolder them until they break without achieving any meaningful results.
A drop in sound should come with a change in voltage, and knowing what that is can more precisely direct your efforts.
Keep in mind that when you had a dark LED, we had to measure voltages to even understand what that meant.
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I’ll try to measure different connections and look for drops during sound loss. Any terminals or pin connections that could be good candidates to start with, ya think?
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Terminals 1-5, and slightly less emphasis on 7 and 9.