S.E.X. 3.0 Kit: Right headphone driver is significantly quieter [resolved]

[Jet]

Previously I had posted about having no sound in my right headphone driver while using the S.E.X. 3.0 Kit and I got a recommendation to just touch up joints T6 and T7 of the right channel output transformer. This seems to have given me sound in right driver but upon further listening it's significantly quieter than the left.

Things I've tried:
Swapping the tubes again yet the channel imbalance doesn't follow the tubes.
Hooked up the S.E.X. 3.0 amp to a digital source and played a test tone, it made it very clear that the right driver had quite a bit more volume.
Using different RCA cables.
Different pairs of headphones.
Everything has passed resistance and voltage checks.

Thank you for the help on my previous post yet I still need some assistance.
Attached is a current picture of the wiring in my kit.

[Paul Birkeland]

Here's a joint that doesn't look soldered.

I see lots and lots of untrimmed leads.  I would get a set of side cutters (something like the CHP-170) and trim all those random leads back. 

[Jet]

I've cleaned up those untrimmed leads and took a look at that joint, it feels solid but I'll be sure to touch it up. While checking it out I discovered the terminal next to it (36U) looks really off up close and actually feels quite loose! I'm gonna redo everything on that terminal tomorrow.

Thanks so much for leading me in the right direction, I'll give an update once it's done.

[Jet]

I touched up those joints yet when I use the amplifier the left driver is still louder than the right.
Any other suggestions?

[Doc B.]

You might go back and redo your voltage measurements. Note any differences between channels now that you have the circuit working.

[Paul Birkeland]

You appear to be missing the resistor at A10.

[Jet]

The resistor is at A10, it's just that you can't see it in the angle of the picture.
I did voltage checks again, everything is within the recommended values.

[Paul Birkeland]

Can you post the make and model of your DVM?  We can help you send a 60Hz tone into your amp and measure it with your meter if it's sufficiently sensitive.

[Jet]

Sure, I'm using a Klein Tools MM320 Digital Multi-Meter.

[Paul Birkeland]

That won't quite get the job done.  You'll need a meter with a 2V AC scale (yours only goes down to 200V, which is totally perfect for residential electrical work).

This one is generally pretty easy to find close by, but if you're not in the US let me know where you are and I'm sure I can find something appropriate that's close by.
https://www.harborfreight.com/11-function-digital-multimeter-with-audible-continuity-61593.html

[Jet]

I should be able to get that exact multi-meter in the next few days, I'll give an update when I do.

[Paul Birkeland]

If A9 and A8 are allowed to touch, you would get really low output, though I would expect some deviations in some of the voltages under those circumstances.

[Jet]

Got the exact meter!
What's the next step?

[Paul Birkeland]

You can download a 60Hz test tone or use a signal generator app on a phone/tablet with a headphone output, then feed that 60Hz tone into the amp with the source device turned all the way up.

You will want to set the meter to the 2V scale and measure the AC voltage between ground and each center pin of each RCA jack, then ground and each outer (non-ground) lug of the volume pot, then each middle lug with the pot about half way up.

You should see about 0.3V going into the RCA jacks, and some attenuation of that voltage appearing at the output of the volume pot. 

None of these tests (so far) require the amp to be on, so you can get a feel for doing this without the amp on.

[Jet]

Finally got the chance to do the test, everything is around your recommended value of 0.3 AC voltage only being off by around 0.015.