Crackling and static in the right channel [resolved]
- Thread starter Cowwe
- Start date
Yeah, it's definitely the pins not making good contact or some parts being dirty. Depending on how I insert the tube (depth or slight angle differences) my Crack either works perfectly, makes some background noise or won't start at all.
I've had the amp turn itself off a couple times while listening, and slightly moving the power tube turns it on again.
How would you suggest to clean the pins and socket? Is using alcool okay?
I've had the amp turn itself off a couple times while listening, and slightly moving the power tube turns it on again.
How would you suggest to clean the pins and socket? Is using alcool okay?
Deoxit is the best thing I have found for cleaning contacts.
If that doesn't do I use a cutting torch tip cleaner. Which is basically a tiny hole file.
I would also check your volume pot connections again. I had a similar problem years back when I first built mine that ended up being a bad joint on the volume pot. Messing around with the tube was flexing the top plate enough to flex the wire braid to the pot and make/break contact.
If that doesn't do I use a cutting torch tip cleaner. Which is basically a tiny hole file.
I would also check your volume pot connections again. I had a similar problem years back when I first built mine that ended up being a bad joint on the volume pot. Messing around with the tube was flexing the top plate enough to flex the wire braid to the pot and make/break contact.
My kit is officially making me go insane.
It had worked flawlessly for 2 days, then as I was listening it turned itself off. Now it's back to the same issue, where for some reason the amp turns itself off and if I wiggle the tube ever so slightly it turns itself on again (until it happens again).
I thought maybe vibrations from me moving at my desk might be moving the tube and breaking some contact, but it has happened even while I wasn't touching anything.
I went and reflowed a solder joint at terminal 13 since the red wire didn't look well covered, closely inspected every joint once mroe and tested the voltage as usual: everything is within standard values.
Setting the Crack to stand vertically, I went with the chopstick test again and tapped on all joints, cautiously moved the octagonal socket pins left and right and lightly pulled/pushed on wires: no changes at all in the sound and the amp kept sounding perfect for a good 10-15 minutes.
I put the kit back to its place and within 5 minutes of listening it turned itself off once again.
I have wiped the inside of the socket a bit and it looks clean enough to me. The pins themselves also feel pretty tight, and I'm not sure how I would go about messing with them to make a better contact.
Once more, please let me know if you have any ideas what else I can try. If you would like, I'm willing to send a close up picture of every single joint you'd like to see.
This amp is such a joy when it works, but this situation is so very frustrating.
It had worked flawlessly for 2 days, then as I was listening it turned itself off. Now it's back to the same issue, where for some reason the amp turns itself off and if I wiggle the tube ever so slightly it turns itself on again (until it happens again).
I thought maybe vibrations from me moving at my desk might be moving the tube and breaking some contact, but it has happened even while I wasn't touching anything.
I went and reflowed a solder joint at terminal 13 since the red wire didn't look well covered, closely inspected every joint once mroe and tested the voltage as usual: everything is within standard values.
Setting the Crack to stand vertically, I went with the chopstick test again and tapped on all joints, cautiously moved the octagonal socket pins left and right and lightly pulled/pushed on wires: no changes at all in the sound and the amp kept sounding perfect for a good 10-15 minutes.
I put the kit back to its place and within 5 minutes of listening it turned itself off once again.
I have wiped the inside of the socket a bit and it looks clean enough to me. The pins themselves also feel pretty tight, and I'm not sure how I would go about messing with them to make a better contact.
Once more, please let me know if you have any ideas what else I can try. If you would like, I'm willing to send a close up picture of every single joint you'd like to see.
This amp is such a joy when it works, but this situation is so very frustrating.
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Socket looks clean. As it is new it should be. You could try and bend the contacts in a fraction with a tiny screwdriver. Cleaning the pins by pushing the through a sheet of Scotchbrite soaked in DeOxit worth doing. Wiser heads might be able to say why the unit actually switches off and which pin might be the cause. If it is safe to do so, have a poke around with the chop stick when it is this "off" state.
Paul Joppa
Moderator
You used the phrases "turned itself off" and "turned itself on" - does this happen instantly, or does it fade in and out? Is there a loud click, or a thump, or does it just go silent? Have you measured voltages while it is silent (yes that's hard to do!)?
It iis likely to be a thermal expansion that causes a disconnect. These details might help locate the intermittent connection.
It may be a broken wire, where it was nicked when the insulation was removed and the insulation crept back to cver the which then broke in subsequent handling. A little gentle yanking of wires can reveal this kind of problem.
It iis likely to be a thermal expansion that causes a disconnect. These details might help locate the intermittent connection.
It may be a broken wire, where it was nicked when the insulation was removed and the insulation crept back to cver the which then broke in subsequent handling. A little gentle yanking of wires can reveal this kind of problem.
When I say it "turns itself off/on" I mean it happens as if I would be removing the plug or flipping the power switch. The tubes start glowing fainter until they go dark, while the volume gets lower until it's silent (in the span of about 5 or 10 seconds). There are no clicks or noises, aside from two quiet thumps at the very end (one per ear), which I'm positive the amp does normally whenever you would turn it off.
From what I have noticed it's not fading in and out, but rather it fades out and stays like that until I mess with it. I haven't tried leaving it alone after it fades out to see if it fades back in, though.
My amp has been unplugged for a couple hours now so it's completely cool, but it isn't turning on if I plug it in (I would need to go and move the tube).
I'm going to try and measure the voltages right now as long as it's in this state.
Thank you again for your patience in assisting me, Paul.
From what I have noticed it's not fading in and out, but rather it fades out and stays like that until I mess with it. I haven't tried leaving it alone after it fades out to see if it fades back in, though.
My amp has been unplugged for a couple hours now so it's completely cool, but it isn't turning on if I plug it in (I would need to go and move the tube).
I'm going to try and measure the voltages right now as long as it's in this state.
Thank you again for your patience in assisting me, Paul.
Those conditions would be neither tube conducting. Can you see the orange glow from either tube under these conditions? This hypothesis doesn't fit the "instant off" condition you describe though.
This is very much not an issue with tube socket pin fitment, as both the 12AU7 and 6080 are unable to operate under these conditions.
This is very much not an issue with tube socket pin fitment, as both the 12AU7 and 6080 are unable to operate under these conditions.
OK, there are wires going from B7/B8 to the power transformer. If both tubes are not glowing but the high voltage remains, then one of those wires is not well connected or broken.
Don't ignore that it may well be the wires at the power transformer that feed B7/B8 that are loose.
I have a brief update, bringing both good and bad news about my situation.
The good news is that reflowing B7 and B8 seems to have fixed the issue with my amp dying and coming back alive. I have kept it on for a number of hours and the amp stays on.
The bad news is that I am back to fighting with the the crackling noise in the right channel.
Last night I went through the usual chopstick test, and I have found that lightly pushing on the black wire to terminal 3 sends static noise on both channels. I don't know whether this could be the culprit for my issue, but I will be starting from reflowing there.
The good news is that reflowing B7 and B8 seems to have fixed the issue with my amp dying and coming back alive. I have kept it on for a number of hours and the amp stays on.
The bad news is that I am back to fighting with the the crackling noise in the right channel.
Last night I went through the usual chopstick test, and I have found that lightly pushing on the black wire to terminal 3 sends static noise on both channels. I don't know whether this could be the culprit for my issue, but I will be starting from reflowing there.
I would carefully examine the black wires that meet at the headphone jack. It's extremely common for builders to not capture both of them with solder adequately, and this can cause a lot of issues.
I went and soldered terminal 3. Now the joint looks nice and well connected and doesn't react when I try to mess with it with a chopstick.
Unfortunately this didn't solve the noise issue.
The joint at the jack terminal with two black wires connecting honestly looks very good to me. The two wires seem to be covered in solder and they don't make any static or crackling when I mess with them.
I have spent a long time trying to find the joint that's causing the noise but I haven't been able to get anything out of it. I can't even tell whether the noise changes by rocking the tube anymore.
My voltage readings are the following:
1) 79,6 2)172,5 3)0 4)172,6 5)79,7
6)0 7)105,4 8)0 9)106,8 10)0
I have noticed that there is a 1,4v difference between terminal 7 and 9. Could this be an hint?
Unfortunately this didn't solve the noise issue.
The joint at the jack terminal with two black wires connecting honestly looks very good to me. The two wires seem to be covered in solder and they don't make any static or crackling when I mess with them.
I have spent a long time trying to find the joint that's causing the noise but I haven't been able to get anything out of it. I can't even tell whether the noise changes by rocking the tube anymore.
My voltage readings are the following:
1) 79,6 2)172,5 3)0 4)172,6 5)79,7
6)0 7)105,4 8)0 9)106,8 10)0
I have noticed that there is a 1,4v difference between terminal 7 and 9. Could this be an hint?
I just went ahead and reflowed most of the joints in the amp, basically only leaving alone the 9 pin socket and the connection around the power switch. I made sure to pay particular attention to the octagonal socket and the part where the black wires meet at the jack. Nonetheless, this did not solve anything. Right now I am at a loss on what to do, as the amp is still unusable as it is.
One thing that keeps puzzling me, is that a couple of weeks ago the noise did react to moving the 6080, and that after messing with it for a bit the amp did work flawlessly for a period of time. It only came back after I reflowed the bad joints at B7/B8, which fixed my issue with the amp turning itself off.
Hoping that you won't mind the wall of text, I'm going to reorganize the main results from my testings so to have the situation as clear as possible:
-The crackling noise appears soon after the amp is on. I would say after about 15 seconds, whereas when the problem first appeared it only started after a longer period of warm-up.
-The noise is exclusively in the right channel. If I just barely unplug my headphone jack I can hear it in both (since that's when the headphones normally play in mono).
-The noise does not depend on whether I have the RCA's connected or not, and it does not change depending on which wall outlet I plug it in (not even a different house).
-I have tried multiple driver and power tubes and all of them have the same issue. Wiggling either tube does not have an audible effect, and the socket and tube pins look rather clean.
-The noise doesn't change depending on volume. It's always there at the same volume.
-The chopstick test did not reveal any weak connection. Even lightly pulling/pushing on wires I couldn't notice any audible reaction.
-Applying pressure on the chassis in several different positions did not reveal any audible changes either.
-I have reflowed the majority of joints, including those that looked alright to my eyes, and the voltages always measure within the standard values. The one thing I noticed, as I mentioned in a previous message, is that there is always a discrepancy of about 1.5V between terminals 7 and 9, whereas the other terminals (for example 1 and 5) mirror each other much more closely.
One thing that keeps puzzling me, is that a couple of weeks ago the noise did react to moving the 6080, and that after messing with it for a bit the amp did work flawlessly for a period of time. It only came back after I reflowed the bad joints at B7/B8, which fixed my issue with the amp turning itself off.
Hoping that you won't mind the wall of text, I'm going to reorganize the main results from my testings so to have the situation as clear as possible:
-The crackling noise appears soon after the amp is on. I would say after about 15 seconds, whereas when the problem first appeared it only started after a longer period of warm-up.
-The noise is exclusively in the right channel. If I just barely unplug my headphone jack I can hear it in both (since that's when the headphones normally play in mono).
-The noise does not depend on whether I have the RCA's connected or not, and it does not change depending on which wall outlet I plug it in (not even a different house).
-I have tried multiple driver and power tubes and all of them have the same issue. Wiggling either tube does not have an audible effect, and the socket and tube pins look rather clean.
-The noise doesn't change depending on volume. It's always there at the same volume.
-The chopstick test did not reveal any weak connection. Even lightly pulling/pushing on wires I couldn't notice any audible reaction.
-Applying pressure on the chassis in several different positions did not reveal any audible changes either.
-I have reflowed the majority of joints, including those that looked alright to my eyes, and the voltages always measure within the standard values. The one thing I noticed, as I mentioned in a previous message, is that there is always a discrepancy of about 1.5V between terminals 7 and 9, whereas the other terminals (for example 1 and 5) mirror each other much more closely.
I would try this: https://forum.bottlehead.com/index.php?topic=11676.0
The 1.5V difference between 7 and 9 is not anything concerning.
The 1.5V difference between 7 and 9 is not anything concerning.
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