Help, voltage problem!

[Paul Birkeland]

I forgot to connect the pc to the amp  ;D
The pot reads 1.61-1.62v
Terminal 6 reads 14.6v
Terminal 10 reads 1.83v

Woah, yeah, there's a problem there!

So all four terminals on the pot gave ~1.62V?  That's a good sign.

Can you very carefully repeat the measurements, but this time measure the AC voltage at T1 and T5?  Most meters should still pick up on the 60 Hz AC component and block the DC.  If you see something like 12V AC, that's a valid measurement.  If you see something a lot higher, then let me know and we can tweak things to get your measurements. 

 

[smallmany]

T1=177.6v
T5=176.9v

Terminal 6 and 10, I must have read wrong, after doing numerous tests, T6 is on average is only 2-3 times larger than T10. i.e: T6=2v    T10=.7v

Also, at maximum volume, T6 and T10 both have a reasonably close value of 15.3v.

 

[Paul Birkeland]

Well, while those voltages are sort of meter nonsense, they would suggest that the 60Hz signal is getting into the 12AU7 and being amplified properly. 

This would leave a funky 6080 (which may have been damaged when run with the missing wire from B2 to 2L), or a bad solder joint on the 6080 tube, specifically the wiring to and from T9 and T10, as well as the feed from T5 to B4.

-PB

 

[smallmany]

Is there a way to test if the 6080 tube is in fact damaged?

 

[Paul Birkeland]

The easiest way would be to pop in a different 6080 and see if you get the same results. 

I'd really go over those specific solder joints first. 

 

[smallmany]

I've rewetted those joints but to no avail. 


Update: I forced the pot counter clockwise, now i get no channel imbalance at low volume and the sound is even. Im contemplating whether or not the sound quality worsened or not

                                              e
                                    s
                          r
Definitely wo

 

[Paul Birkeland]

I'd see if you can source a 6080 locally.  They are an incredibly common tube, and should be available at an old time TV repair or general electronics repair shop.

 

[smallmany]

Replaced the stock pot with alps blue velvet, balance issue is gone.
The stock pot drove me insane, you guys should give the option of purchasing a pot that isn't so crappy

Looking forward for the speedball .  Thanks for those who replied, especially PB. ;D

 

[Paul Birkeland]

Replaced the stock pot with alps blue velvet, balance issue is gone.
The stock pot drove me insane, you guys should give the option of purchasing a pot that isn't so crappy

Please let us know if you find a high performance potentiometer at a decent price that we can be 100-1000 of at a time.

(FYI - the PEC pot that is beloved on many forums actually has poorer channel balance than the pot we use, as does the dual 100K control that you can get at Radio Shack.  We also offer advice on how to add a 10 cent pair of resistors to solve the channel balance issue)

 

[Chris65]

Please let us know if you find a high performance potentiometer at a decent price that we can be 100-1000 of at a time.

http://www.tocos.com