Left noise

[audiophileboss]

I changed the pot on my crack...works, sounds better, but during the breaks between music it produced a hum in the left channel mainly. Now, an led did not work so I resoldered it and now its fine.

Could the led be my problem?
Also, does ground wire have anything to do with the noise?

[Grainger49]

Bad grounds are a frequent source of hum. 

[audiophileboss]

Now how can I fix my grounds?

[audiophileboss]

Btw I changed 1 led no difference. I am hereing a hum...ac hum. How can I eliminate that

[Grainger49]

I have posted this three or four times before.  Hum can be from ground or circuit common.  Here is the path to rewet all ground terminals/pins for the Crack:

The start of the grounding points is terminal 3.  This jumps to the 2 left lugs of the volume pot and back from there to the RCA jacks outer connector/shield.  From the top left lug of the volume pot there is a grounding jumper to the two bottom lugs of the headphone jack.  This jack may be different than what is being delivered today.

Also from terminal 3 you go to the center lug of the 9 pin tube socket.  This is the ground route for the LEDs in the 2 cathode circuits of the driver tube.

The power supply ground comes from those bottom headphone jack terminals to terminal 12.  From there it jumpers to terminal 14 and ends at terminal 20.

The heater (AC) supply is a ground wire from transformer terminal 4 to terminal 22.

Ok, so all this means you should clip on to the chassis (which is screwed to terminal 3 the source of all the grounds).  Tracing from the plate outward you should read zero to T3, Volume 2 left lugs, both RCA outer conductors, headphone jack bottom terminals, T12, T14, T20, center pin of the 9 pin socket, and to T22.

Other grounds that should be solid are pin 8 of the large tube, pin 4 and 5 of the small tube, T8, T11, T14, T16, T17, T20, T21 & T22.

[Paul Birkeland]

Now how can I fix my grounds?

Put the stock pot back in.

[audiophileboss]

Heavens no...stock pot is horrible . I need to figure out this hum though. I am going to try shileding some grounds and see if that changes anything

[Paul Birkeland]

Heavens no...stock pot is horrible . I need to figure out this hum though. I am going to try shileding some grounds and see if that changes anything

That' not really the point.  If you put the stock pot back in, and the noise is gone, then you have concisely found the source of your noise.

Shielding grounds is wrapping grounds in grounds, I wouldn't expect that to do much.

[audiophileboss]

This pot is more sensitive. The stock pot was too cheap to show the hum. I need to rectify the hum without removing upgrades.

[Paul Birkeland]

This pot is more sensitive. The stock pot was too cheap to show the hum. I need to rectify the hum without removing upgrades.

I'd suggest that your "upgrade" is potentially a downgrade, or there may be issues with the installation.  Wouldn't you at least want to eliminate it as the issue?

[audiophileboss]

Ok, paul youve got a point. I ordered another pot...more hifi. Lets see if its the same, better or worse. My sound is much better with this pot, but hum is my only problem. Anyother suggestions as to what i could do to eliminate the hum?

[Paul Joppa]

"Any other suggestions as to what i could do to eliminate the hum?"

The engineering answer is to first determine what is the source of the hum. That's usually a lot more work than fixing it afterwards - but often much less work than trying every solution you can find until one of them works!