SEX 3.0 Transport Damage - can't find the source

[Paul Birkeland]

I listed out 7 quick tests to do to see where the issue may be.  You've done 2 of them, could you do the next 5 and report your results?

-PB

[yay]

Yes, ofc. I just stopped with the other tests since i damaged something whil doing test 3 wrongly.
Should i open another thread for that damage caused?

[Paul Birkeland]

There aren't any voltage issues that I could see.  Please start over with the tests and let us know.  Also, if you are able to get a 60Hz tone fed into your SEX amp, we can use that to check on things as well.

-PB

[yay]

I finally have some time to take care of this once and for all now.
I did the jumper tests, and this is my result:

The upper and lower lugs on the volume pot on the headphone jack side of the amp need to be temporarily shorted together, then see if the issue goes away.
-> Left and Right channel coming from only the left speaker, both the same volume and also the correct volume.

If the issue is still present, remove that jumper and put it between the upper and lower middle lugs on the volume pot, then recheck.
->  Left Channel coming from the Left Speaker, correct volume. Right Channel and Right Speaker no sound.

If that didn't change the issue, remove that jumper and jumper pin 10 on each 12 pin socket together, then recheck.
-> Left and Right channel coming from only the left speaker, both the same volume and also the correct volume.

If that didn't change the issue, remove that jumper and jumper pin 3 on each 12 pin socket together, then recheck.
-> Left and Right channel coming from only the left speaker, both the same volume and also the correct volume.

If that didn't change the issue, remove that jumper and jumper terminal 3 to terminal 17, then recheck.
-> Left and Right channel coming from only the left speaker, both the same volume and also the correct volume.

If that didn't change the issue, remove that jumper and jumper the upper and middle inside headphone jack terminals together, then recheck.
->  Left Channel coming from the Left Speaker, correct volume. Right Channel and Right Speaker no sound.

If that didn't change the issue, remove that jumper and jumper the upper and middle outside headphone jack terminals together, then recheck.
->  Left Channel coming from the Left Speaker, correct volume. Right Channel and Right Speaker no sound.

[Paul Birkeland]

I strongly suspect you have a broken wire between the binding posts and the headphone jack.

-PB

[yay]

Should i just replace the whole CAT5 cable there and see if the issue persists?

[Paul Birkeland]

Each length of wire should measure about 0 ohms from one end to the other.  I would measure them and see where you might have a break.  These tend to happen near the ends of the wire, so it may be fixable without doing much modification.

The reason I believe you have a broken wire is that you shorted together the outputs of both channels at the headphone jack, and this goes from the headphone jack to your speaker jacks.  One channel works in this scenario and one does not, so the only plausible conclusion is that the wired connection from the headphone jack to speaker jacks isn't working.

Another way to test this would be to plug in headphones and check that output.  It may provide another useful data point.

[yay]

I believe the break is somewhere in the middle of the CAT cable, under the shield. After unpacking and looking at the damage, it looked like at that spot it might've gotten some damage.
What are the specifications of the CAT cable? I only have one without the shielding and in 26AWG around.


Would this cable work well? It's AWG 24, and looks like this: (see attachment)

[Paul Birkeland]

We use plenum rated (better with heat) shielded cat5 with solid core conductors.  If you can find some with shielding and solid core conductors, it should work just as well as what we provide.

[yay]

So i removed the CAT5 cable, and then tested each strand for resistence, and it measured 0ohm on all of them. Seems like this isn't actually the reason?

[Paul Birkeland]

If that didn't change the issue, remove that jumper and jumper the upper and middle outside headphone jack terminals together, then recheck.
->  Left Channel coming from the Left Speaker, correct volume. Right Channel and Right Speaker no sound.

That would still tend to suggest an interruption in that wire.  The other possibility is that the CAT5 on the output transformer on the offending channel has shorted itself out.  There isn't a good way to measure this, you'll just have to inspect the wiring.  Look for two wires that may have been crushed together by shipping damage.

[yay]

Alright, so i switched out the CAT5 cable for the input/output incl. the ones coming from the transformer.
Resistence checks all check out, Voltage tests fail for terminal 2.
I measured only 1V there, all other tests worked out.
No sound coming from the right channel, i checked out if it was coming from a RCA input with too much solder, but they are not shorted together.
Doesn't even seem like an issue with the new cables at all?

[Paul Birkeland]

You now have a voltage issue, so that's something to go for.  If you have 1V at terminal 2, your voltage at terminal 6 should be off as well.

[yay]

Full measurements:

Terminal 2: -1.16V
Terminal 3: 18.8V
Terminal 4: 0.02V
Terminal 5: 0.00V
Terminal 6: 411V
Terminal 7: 413V
Terminal 10: 390V

Terminal 16: 85.3V
Terminal 17: 19.2V
Terminal 18: 0.02V
Terminal 19: 0.00V
Terminal 20: 395V
Terminal 21: 412V
Terminal 24: 388V

H2: 3.38V
H5: 3.38V
H4: -3.18V
H7: -3.18V

[Paul Birkeland]

The 150K 2W resistor may not be adequately connected.

Having 0V at terminal 2 could be caused by an internal tube short, but you don't have enough voltage difference between 6 and 7, so that's not the case.

A dead triode would leave you with about 400V at terminal 2.