Loud Pop In Right Channel Followed By No Sound [resolved]

[2wo]

While you are in there tugging on wires check that one isn't broken under the insulation. This usually happens not far from the striped end...John

[Colonl_Charisma]

Thanks Paul. I'm going to reflow all joints again. On the octal socket I have 2 holes that can be filled. Should I fill both holes or is it not important? I know the manual says to fill both if both are used. I tried to only use one of the holes on all the pins.

Thanks, John. I have been wondering about that, but since all of my resistance and voltage checks are looking good I have not really looked into it.

[Paul Birkeland]

If there's nothing in the hole, you can leave it alone.

[Colonl_Charisma]

Paul, is there any chance that the tubes could have been damaged by the amp? Haha this seems like wishful thinking. However, as I reported before both GE 6080 tubes that I have tried will glow blue on startup and then flash followed by some tiny sparks inside the tube. The 6080 then burns normal. I don't have another tube amp (Crack will be my first) to test the tubes to see if they work in another system.

Also, I appreciate the info regarding the double hole octal sockets. I will not add any extra solder to them.

[Paul Birkeland]

I haven't ever seen that happen.  The only time I can remember seeing this happen is when someone didn't have their power transformer screws on tightly, then didn't get 0 ohms on the resistance check at the end of the manual for the end lugs of each 6 lug strip, so they added in wires to connect them all.  That sent that particular kit on the fritz but it was OK once it was returned to normal. 

When you first turn the kit on, the 6080 doesn't conduct because the cathode is cold and needs to be heated up by the filament.  Generally your symptoms could be explained by a gassy 6080, but that ought to go away with use and shouldn't be an issue when you have a replacement tube.  Since you have two tubes doing the same thing, that does suggest an issue with the amp itself, as damaging a tube to the point of making it gassy is going to present many other obvious issues.

Maybe a fresh shot of the wiring or two will reveal something we have missed thus far.

[Colonl_Charisma]

I am glad to hear that. My intuition tells me that the issue lies with the amp and not the 6080 tube too.

I made a quick Imgur album of some new pics of my build. I did an overhead shot of the wiring and I included some closer shots of wiring and solder joints.

https://imgur.com/gallery/67g9Vbx

[Paul Birkeland]

A2 looks pretty suspect to me.  Wrapping and crimping leads where you can will form joints that are more solid.  Naturally you could also swap the 12AU7, but a 12AU7 that would make issues like that should come with major DC voltage issues.

[Colonl_Charisma]

Thanks PB! I will take a look at A2 tomorrow morning. If you see anything else that looks suspect let me know and I'll touch it up tomorrow.

[Colonl_Charisma]

Hi PB,

Cleaned up A2 on the 9-pin. I used my solder wick to remove all solder from the joint. pre-crimped the wire, and then re-soldered it. It looks a lot better. However, the problem still exists. Going to do another chopstick test.

Should the holes on the 9-pin be completely filled? Mine are not.

[Paul Birkeland]

You really only need the solder to flow between the crimped wire and what the wire is crimped to.  Filling the socket holes is not required for a solid joint.

[Colonl_Charisma]

I performed another chopstick test with the volume turned all the way up. I was unsuccessful in locating the troublesome area. No pop or crack from headphones after pushing and pulling on wires, pushing on hardware, or pushing on joints. LEDs still glow fine, tubes burn (there is still a blue glow that then turns into a bright flash once the 6080 tube begins heating up), and resistance and voltage checks are still looking fine. I also cleaned up the octal socket. I used the solder wick to remove excess solder and I crimped wires around the octal pins. I then resoldered all of those joints.

I do have a very loud buzz in my left and right channel. Right channel always goes out after a pop/crack is heard from the right channel without me pushing or pulling on any wires. Loud buzz stays in the left channel. If I move my hand closer to the hardware then the buzzing gets louder, and if I move my hand away from the hardware the buzzing returns to a lower level.

I have no clue what else I can do.

[Paul Birkeland]

That could indicate loose hardware on the amp, though having some buzzing when the volume pot is all the way up and nothing is plugged in would be totally normal.


-PB

[Colonl_Charisma]

That's fair about the buzzing probably going away once I have more things plugged in besides the headphones.

Are there any other tests I could perform? Any chance I could have a broken wire somewhere, or would the resistance and voltage checks catch that?

[Paul Birkeland]

The chopstick test usually catches broken wires pretty effectively.  You did use the white nylon insulating washers when mounting the power transformer, right?

[Deke609]

If I move my hand closer to the hardware then the buzzing gets louder, and if I move my hand away from the hardware the buzzing returns to a lower level.

I would try tightening all the screws/nuts that attach the hardware. With special attention to the ground lug near the power inlet and any terminal strip  to which a black wire attaches to the lug that bolts to the chassis.

If that doesn't help, I'd go over the joints with A LOT MORE HEAT and maybe remove a bit of solder (optional). I looked at the pics you posted first in this thread. Really nice, neat build. But one thing stuck out: you used lots of solder and yet almost none of the wires have melted insulation near the joint. Almost all of them look as if they were freshly cut and never exposed to heat. That's possible to achieve with really high heat and really short dwell time, but none on your joints look like high heat was involved. So I suspect you used low temp and fed a lot of solder onto the lug.  If either the wire or the lug wasn't making good contact with the soldering iron tip, low temp is a recipe for a cold joint.  At low temps, I can imagine the rosin core (inbuilt flux) of the solder not burning off and instead coating either the wire or the lug, whichever wasn't fully heated. That stuff is insulating. 

If you have an adjustable iron, I'd crank it up to 800F and give each joint a good heating  -- other than the red HLMP diode attachments.

cheers and good luck, Derek