HUGE channel imbalance

[Tonydatigerr]

I am getting a lot of imbalance at all volume levels. The left channel seems to be at least twice as loud as the right. All my voltages and resistance checks came back correct - did I still do something wrong or do I need to let the tube warm up? Thanks in advance for the help!

 

[Paul Birkeland]

If the voltages are all OK, I'd suspect a bad solder joint - probably on the volume control, or at the headphone jack.

 

[Tonydatigerr]

Turns out there were a couple loose connections at the headphone jack.
I went back and checked the B voltages and they seem to be off.

B1: 141
B2: 158
B3: 140
B4: 90

edit: Right channel still quieter than left.

 

[Tonydatigerr]

Hmm... just went to the windows sound settings to re-adjust for the temporary fix and noticed that I lose everything from the right channel when I turn the left down to 0, leaving the right channel at 100. So it appears that nothing is making it through the right channel?

 

[Paul Birkeland]

T1 also has 141V?

Is the LED at A8 glowing?

Are both halves of the 12AU7 glowing?

 

[Tonydatigerr]

Yes, T1 is also at 141V - it was 115V before I installed the 6080.

No, it is not.

Yes, both halves are glowing.

 

[Paul Birkeland]

If you remove the 6080, does it pop back down to 115V?  (My guess is that it does not)

This can happen if one of the connections that shorts A4/5 together isn't well soldered, if the wire going to A7 isn't well connected, if the ground connections at the volume control aren't well soldered, if the LED isn't well connected, and lastly if the wire going from T1 to A6 isn't well connected. 

 

[Tonydatigerr]

No, it goes up to 220. I just redid all the connections you listed and the 2nd LED is still not lighting up. It was actually lighting up a couple days ago, but then I felt like I had to go and "fix" a couple solder joints and guess I missed it up...

Here are pictures of my board in case there is something obvious that I am doing wrong:

https://www.dropbox.com/s/iv9ly4axjp8tha5/IMG_20140130_001447.jpg
https://www.dropbox.com/s/je3f3czhl3rx7a5/IMG_20140130_001455.jpg

 

[Paul Birkeland]

I'd go over the list I posted.

 

[Tonydatigerr]

Is it ok that A4 + A5 is soldered like a giant blob (https://www.dropbox.com/s/4471f1b6my52r6e/IMG_20140130_122230.jpg) or do I need to remove the solder between them?

 

[Doc B]

They should be connected, by the wire that attaches to them being threaded through both terminals. The solder needn't be a big blob, but it probably won't hurt anything as long as it is not a cold joint. It should be very easy to reheat it to make sure that it has good continuity.

 

[Tonydatigerr]

If you remove the 6080, does it pop back down to 115V?  (My guess is that it does not)

This can happen if one of the connections that shorts A4/5 together isn't well soldered, if the wire going to A7 isn't well connected, if the ground connections at the volume control aren't well soldered, if the LED isn't well connected, and lastly if the wire going from T1 to A6 isn't well connected.

I triple checked all those connections and the 2nd LED has still not come on. Is there anything else that can cause this?

 

[Paul Birkeland]

You can test the LED with the diode function on your meter.

To get a feel for how it works, try measuring the one that you know works.  This is done while the LED is in the circuit, but with the amp unplugged and powered off. 

 

[Tonydatigerr]

Here are the voltages for every terminal with an expected voltage in the manual. I have denoted voltages that are off with a "*".

1 146 *
2 163
3 0
4 163
5 92
6 0
7 145  *
8 0
9 100
10 0
11 0
12 0
13 163
14 0
15 187
20 0
21 212

A

1 92
2 0
3 1.5
4 0
5 0
6 146  *
7 0
8 12  *
9 0

B

1 146    *
2 163
3 145    *
4 90
5 163
6 111
7 0
8 0

and will do. I will get back to you with the results.

 

[Tonydatigerr]

Hmm. even with the LED that I know work - I was not able to get a reading with the meter (testing with the leads in every possible position).

 

[Paul Birkeland]

Is there a diode checking setting?  Most of the time, this is a special position on the meter. 

 

[Tonydatigerr]

There is a diode checking setting.

 

[Paul Birkeland]

On the diode check setting and the probes in the correct positions, most meters will actually illuminate our LED's. 

 

[Tonydatigerr]

Well, I ended up snapping the lead to the working LED trying to manipulate it into a position to see if I could actually get a reading. I tried getting a reading on the other LED and was still not successful (placing negative lead to negative side of the diode and positive to positive). Where can I buy replacements over the weekend?

 

[Paul Birkeland]

Well, I ended up snapping the lead to the working LED trying to manipulate it into a position to see if I could actually get a reading. I tried getting a reading on the other LED and was still not successful (placing negative lead to negative side of the diode and positive to positive). Where can I buy replacements over the weekend?

On my meter, the probes happen to go the other way.  This may also be the case for your meter.

I have never seen the HLMP-6000 for sale in any store.  We can, however, mail you some.

-PB