Resistance check - fails on one channel

[xavk]

Hi Guys,

So I had a working Crack but I decided to try and tidy up some of my wiring which was too messy for my liking.  Since I completed it, i went back through the resistance checks and all are the same as before (and in line with expectations) apart from one.  Now the red input centre pin gives me a solid 1 on all scales (the other reads 94 as it did before).

During my troubleshooting, I have replaced the phono connector with a new one (Neutrik NYS 367) to eliminate the possibility of a short at that end, I've removed the pot and cleaned it up (there was too much solder on it and there may have been a short underneath the bottom row between the right and centre poles).  Might i have burned out the pot?  Any suggestions on other checks I can carry out to isolate the issue much appreciated.

Thanks,

Xav

[Paul Birkeland]

Did you accidentally remove the wire jumper between the two levels of the pot where the black wires connect?

Also, if your scale will only go up to 100K Ohms, you may need to go up 1 more scale.

-PB

[xavk]

 Jumper is still in place and I get the same result with the scale at 200k and 2000k ("1")

[Paul Birkeland]

There is a red wire going from the center pin of the red RCA jack to the pot, what resistance do you get at the pot end of that red wire? 

[xavk]

Same result either end of the wire.  In comparison, the white cable shows 94.3 at the RCA end and 93.2 at the pot end.

[Paul Birkeland]

What resistances do you see on the other lugs of that level of the pot?

[xavk]

I get zero on both others on that level. 

on the other level I get 1.4k on the centre and zero on the other end (ie the end with the jumper).

[Paul Birkeland]

You'll want to be 100% certain that you don't actually have 0 Ohms at the center of the red jack before replacing the pot.  it's very abnormal for a pot trace to go open, and your tests show that the wiper is making contact and that the bottom end of the carbon track is grounded.

[xavk]

Thanks for all help!  Not sure I know what the next step is though - without replacing the pot, how would i test if i dont actually have 0 Ohms on that centre wire - would unsoldering it from the pot and retesting do it?

[Paul Birkeland]

Listen to the amp.

-PB

[xavk]

So when I plugged it all in, got an odd result.  First, no audio at all on the right (not a surprise).  Second, and unexpectedly, the left audio was unaffected by the volume position - same volume at any position (even at zero).

I have a spare pot in the house so going to swap the original for that later today.  Will report back.

[Paul Birkeland]

You very likely have a wiring error. 

-PB

[xavk]

So I replaced both the pot and the wiring from there to the RCA jacks and collectively that has resolved the issue.  Will look at the pot more closely later....