Resistance check problem [fixed]

[Paul Birkeland]

Well done, your 12AU7 is now operating properly, both LED's must be lit at this point.

Now, the 6080 is being presented with a reasonable operating parameter, but it it sucking current like crazy!

Can you check that the 3K resistors are in fact 3.0K?

Next, triple check that the 100uF/160V caps are connected properly (striped sides out), and that the wires running to the headphone jack leave the outboard terminals (6 and 10) on the terminal strip?  If those wires were connected to 7/9, you would experience these issues (until the 2.49K resistors cooked).

Let me know if these suggestions are helpful, and especially if they are not.

-PB

 

[chavac]

Hmm. Headphone wires appear to be correct to 10 and 6. AFAIK they two resistors are 3k (xicon p 10w 3k j).  And rechecked solder on all caps and location/orientation, all seem correct. Resoldered all four jointed, still no 6080 when I fire it up

 

[Paul Birkeland]

Ah, that's right, you had mentioned that the 6080 doesn't glow?

Does there happen to be white residue in the tube instead of silver residue?

Are you 100% sure the socket is properly oriented?

 

[chavac]

Hmm. Yeah the 6080 doesn't lightup. Which part of the tube would have residue? I don't see any. And the way it's shaped it only fits one way. One thing I just noticed is it looks like the new led I just put in burnt out already/doesn't light up anymore.

 

[adamct]

I think Paul meant is the socket itself properly oriented, not the tube within the socket. I believe the residue would form on the top of the tube, but Paul will correct me if I'm wrong.

 

[Paul Birkeland]

Adam is spot on, if the tube had leaked, the silver coating on the tube would begin to turn white.

Check the socket orientation, if it's off you could create some interesting problems.

-PB

 

[chavac]

Double checked the orientation and appears to be correct with the slot facing the vent. I don't see any white residue at the top, just the silver cap. There does appear to be a metallic sheen around the bottom of the silver cap portion, but nothing I would call white.

 

[Paul Birkeland]

Can you post a pic of the octal socket on your Crack? (including the adjacent terminal strip)

 

[chavac]

https://www.head-fi.org/g/i/903101/default/sort/display_order/
https://www.head-fi.org/g/i/903102/default/sort/display_order/
https://www.head-fi.org/g/i/903103/default/sort/display_order/

They were too large for the forum, so I just uploaded them onto my headfi gallery. Hope that's OK. Added one of the whole board in case I'm missing something obvious

 

[Paul Birkeland]

Can you remove the 6080 and repeat your voltage checks? (your build looks very good BTW)

 

[chavac]

Will the burnt out led matter?

 

[Paul Birkeland]

Not particuarly, I'm looking for the voltages at 1/5 to pop up.

-PB

 

[chavac]

Almost identical to the first set I gave earlier, except A6 has a reading as it did in the second set. The led blinks on when I check it too.

 

[Paul Birkeland]

Ooo, this is good info, can you pop out the 12AU7 and repeat?

 

[chavac]

Ok here's with neither tube in
1  115
2  115
3  0
4  115
5  115
6  0
7  0
8  0
9  0
10  0
11  0
12  (negative probe)
13  115
14  0
15  115
16  0
17  0
18  45
19  45
20  0
21  115
22  0

A1  115
A2  0
A3  0
A4  0
A5  0
A6  115
A7  0
A8  0
A9  0

B1  115
B2  115
B3  0
B4  115
B5  115
B6  0
B7  0
B8  0

 

[Paul Birkeland]

Hmm, there is still a power supply issue, could you pop some photos up of that?  There are a fair number of potential sources, but a photo should make it pretty clear.

-PB

 

[chavac]

https://www.head-fi.org/g/i/903127/a/793222/desktop-headphone-amps-community-gallery/sort/display_order/
https://www.head-fi.org/g/i/903128/a/793222/desktop-headphone-amps-community-gallery/sort/display_order/
https://www.head-fi.org/g/i/903129/a/793222/desktop-headphone-amps-community-gallery/sort/display_order/

 

[Paul Birkeland]

Can I see the area around the diode bridge?

Is the ground lug by the IEC entry socket soldered?

 

[chavac]

The buss wire is solder in the middle to the lug.

https://www.head-fi.org/g/i/903138/default/sort/display_order/
https://www.head-fi.org/g/i/903139/default/sort/display_order/

 

[Paul Birkeland]

Alright, with no tubes in, what is the AC voltage between 18 and 19?