Finished BUT octal tube POPS when touched/jiggled [resolved]
- Thread starter Jsin
- Start date
If the cap lead at terminal 20 gives you a consistent 0 and that's the only joint doing that, you could try a voltage check.
Ok. All was good with the ohms. Tubes glowed (though one half of smaller tube seemed dimmer than the other) but no leds were lit underneath. The voltage test did not give any expected numbers.
I went back and reheated some joints - passed the ohm test - plugged it in to test voltage, no tubes glowing and a blown fuse just from turning on.
Think I keep moving myself backwards somehow.
— high maintenance
I went back and reheated some joints - passed the ohm test - plugged it in to test voltage, no tubes glowing and a blown fuse just from turning on.
Think I keep moving myself backwards somehow.
— high maintenance
What numbers did the voltage checks give? Actually knowing what they are could point us in the direction of your problem.
What value are you using for the fuse? In the absence of a more solid understanding of why your amp is blowing fuses, you may want to go to a 3A fuse. This will allow whatever is ailing your amp to get a bit hotter and make itself obvious. I don't normally recommend this procedure right off the bat, but other than the soldering issues from your first set of photos, everything is in its place and it's quite obvious that you followed the directions well, so this may be a necessary risk to take.
The one thing I can see is one of the UF4007 diodes on the outside of the 6 lug strip. If one diode is backwards, that would cause just about all of these issues.
If one half of the 12AU7 isn't glowing at all, that would be the solder joint on A4/A5 not functioning well. One side not glowing as brightly is more than likely just a production variation in the 12AU7 itself.
What value are you using for the fuse? In the absence of a more solid understanding of why your amp is blowing fuses, you may want to go to a 3A fuse. This will allow whatever is ailing your amp to get a bit hotter and make itself obvious. I don't normally recommend this procedure right off the bat, but other than the soldering issues from your first set of photos, everything is in its place and it's quite obvious that you followed the directions well, so this may be a necessary risk to take.
The one thing I can see is one of the UF4007 diodes on the outside of the 6 lug strip. If one diode is backwards, that would cause just about all of these issues.
If one half of the 12AU7 isn't glowing at all, that would be the solder joint on A4/A5 not functioning well. One side not glowing as brightly is more than likely just a production variation in the 12AU7 itself.
Thanks Paul.
I gave it one more cycle of searching and re-soldering. Ensured the 4007s were all banded where they should be, checked ohms, and then turning it on blew the fuse again.
I can grab some heftier fuses later or tomorrow, but what exactly will I be looking for if those keep it running - how will it show me the problem?
Thanks again for all the attention. Am determined to get this back to where I started at least...
J
I gave it one more cycle of searching and re-soldering. Ensured the 4007s were all banded where they should be, checked ohms, and then turning it on blew the fuse again.
I can grab some heftier fuses later or tomorrow, but what exactly will I be looking for if those keep it running - how will it show me the problem?
Thanks again for all the attention. Am determined to get this back to where I started at least...
J
Components that get hot will discolor, and that will tell you where to look. In the meantime, can you post some fresh build photos for us to look over?
Sounds like I'll be looking to break something - that I know I can do...
Here's some pics of the build with some - hopefully - better attention paid to soldering.
-- might feel better about where I'm at if I hadn't been listening to music through this on Tuesday night --
Here's some pics of the build with some - hopefully - better attention paid to soldering.
-- might feel better about where I'm at if I hadn't been listening to music through this on Tuesday night --
Attachments
Could I see the terminal strip with terminals 17-22? Terminal 19 looks like it has a lead sticking through it that needs to be trimmed off.
Here are both sides. I think you are seeing the wire needing trimming on 20L... but I can't figure how to get in there. Could that be causing an issue of this magnitude?
BTW - ran and got some 3A fuses. What's the process? plug it in - see what discolors - unplug - post?
-- J
BTW - ran and got some 3A fuses. What's the process? plug it in - see what discolors - unplug - post?
-- J
Attachments
I would say that 20L is not soldered.
You'll have to try the 3A fuse and see what sizzles.
If you have more 1A fuses, you can try powering the amp up with no tubes. I'm 99% certain that your fuse will still blow, but it's another test that could be performed.
If you have more 1A fuses, you can try powering the amp up with no tubes. I'm 99% certain that your fuse will still blow, but it's another test that could be performed.
Sure, go ahead and have them in for the 3A test.
That lead poking out at 19 could definitely be shorting the HV winding. Please do trim that first before running the 3A fuse.
SUCCESS!!!
I crimped that wire right to the board, resoldered the LEDs and a couple of other dull looking spots, did an ohm test then - moment of truth - 1A fuse and the tubes glowed. Flipped it over and both LEDs lit! Voltage test was spot on.
Just listened to Kind Of Blue on my Stein 6xx and it sounded magical!!!
1,000 thanks for all the help. Very excited to listen for awhile and then take a run at Speedball.
I crimped that wire right to the board, resoldered the LEDs and a couple of other dull looking spots, did an ohm test then - moment of truth - 1A fuse and the tubes glowed. Flipped it over and both LEDs lit! Voltage test was spot on.
Just listened to Kind Of Blue on my Stein 6xx and it sounded magical!!!
1,000 thanks for all the help. Very excited to listen for awhile and then take a run at Speedball.
raindownthunda
New member
I have a related question regarding a popping noise I have experienced in my new BHC build twice now with two different tubes. Both times the tubes worked fine for 5-10 mins and then I saw a bright white "spark" inside the tube. The first time this happened was with a WE 421a and the spark stayed in the same position on the plate. Both times the white sparks were accompanied by LOUD popping noises, IIRC only out of the right channel. At first I thought this might be a bad tube as I had tried 5-6 other output tubes with no issue before these... but after the 2nd time it happened with a different tube that had been tested as a good tube by the seller, I got suspicious it could be the amp.
I re-inspected the wiring and noticed that the octal socket wiring had moved a bit due to tube flex (and poor judgment on my part) so that two of the octal socket bare wires were VERY close to touching between pins 2 & 3. I am wondering if those wires were close enough to touching that this would explain the white spark on the plate accompanied by LOUD popping?
I've rewired the pin 2 & 3 wires so they are definitely not going to touch. I also reflowed a few solder joints at the same time, including the grounds for the headphone output. So far I've run both of the tubes I experienced issues with for 25+ mins each with no sparks/popping. I have PTSD from wearing my headphones when the popping happened, so I want to get your input on whether or not the issue I experienced sounds like faulty wiring that has now been fixed, OR if it could still infact be bad tubes that spark/pop very intermittently. I would hate to get rid of nice tubes that are perfectly fine. I have heard about tubes "arcing" but don't know if the issues I'm having sound like arcing.
Attaching a pic of the "white spark" glowing on the right plate of the WE421a. It was pretty bright (camera did not capture the brightness very well). Thanks in advance!
I re-inspected the wiring and noticed that the octal socket wiring had moved a bit due to tube flex (and poor judgment on my part) so that two of the octal socket bare wires were VERY close to touching between pins 2 & 3. I am wondering if those wires were close enough to touching that this would explain the white spark on the plate accompanied by LOUD popping?
I've rewired the pin 2 & 3 wires so they are definitely not going to touch. I also reflowed a few solder joints at the same time, including the grounds for the headphone output. So far I've run both of the tubes I experienced issues with for 25+ mins each with no sparks/popping. I have PTSD from wearing my headphones when the popping happened, so I want to get your input on whether or not the issue I experienced sounds like faulty wiring that has now been fixed, OR if it could still infact be bad tubes that spark/pop very intermittently. I would hate to get rid of nice tubes that are perfectly fine. I have heard about tubes "arcing" but don't know if the issues I'm having sound like arcing.
Attaching a pic of the "white spark" glowing on the right plate of the WE421a. It was pretty bright (camera did not capture the brightness very well). Thanks in advance!
Attachments
It would be hard to say without seeing how close the wires were before, but if pins 2 and 3 on the octal socket touch, that's not a good situation!
