Resistance check errors with S.E.X 2.1 build.

[Noskipallwd]

Hello, finished wiring my sex kit earlier today. I performed a resistance check and have a few errors. All readings were fine except:

Left input RCA center pin reading 75k should be 100k, right channel is fine.
T14 and T24 readings are variable with pot position as they should be.
Both start at close to 0 ohms, turn the pot up they have an imbalance. Maximum volume has:
T14 close to 1000 kohms while T24 reads 280 kohms
A4 and B4 vary as well.
At lowest both are around 200k
At max volume:
A4 close to 1000k and B4 reads 280k
I have checked the wiring a number of times, reflowed some solder but can't seem to find the problem. All help is greatly appreciated.

Cheers,
Shawn

 

[Noskipallwd]

Thanks Grainger, the resistors look ok, but I just noticed my RCA center pin readings are varying with the pot. Which is not supposed to happen. A bad pot wouldn't cause that would it? I'm just not seeing any miswires, all my other resistance readings are fine. Maybe I will pull the pot and try another, I have a few in my stash.

Cheers,
Shawn

 

[Paul Birkeland]

Left input RCA center pin reading 75k should be 100k, right channel is fine.
T14 and T24 readings are variable with pot position as they should be.
Maximum volume has:
T14 close to 1000 kohms while T24 reads 280 kohms

Mk, so the 75K/100K pair would indicate something partially shorting out the 75K side of the pot.  Is T14 100K or 1000K (1M)?  Then we have T24 reading 280K.  This is odd, as T24 must be somewhere along the carbon trace of the volume pot, which has an esatablished (low) impedance of 27K, but T24 is somehow showing more resistance to ground at 280K.

I'd double check those readings, then double check the solder joints on the left channel, especially the black wires that establish the ground connections.  If there is a bad connection somewhere in that chain, it could cause erratic readings.  I wouldn't recommend changing the pot at this time.  You could try measuring the resistance between the outer lugs on each deck to double check if you like.

-PB

 

[Noskipallwd]

Ok not making progress, so I changed the pot with an identical one.. Resistance at the same positions are off but changed.

At minimum volume
Left center pin 1.5 ohms right is ok
T14 1.5 ohms
A4. 222 ohm

T24. 97 k
B4.  97 k
At max volume
Left center pin. 75 k right ok
T14. 97 k
A4. 97 k
T24. 74 k
B4.  74k

All other readings are good, I'll keep looking for wiring problems, gonna take a break, my head hurts!

Cheers,
Shawn

 

[Noskipallwd]

Well, I thought I would update. Found the problem(s), the non-stock left RCA jack I installed was defective. The center pin was making intermittent connection with the outer ground. Also, one of my ground wires on the left channel was not making proper connection. Looks like I might have nicked it while stripping. I was poking solder joints looking for bad ones and it broke when I touched it. All resistance readings are good. Passed the smoke and voltage tests and is driving my BK12-Ms beautifully. Norah Jones on vinyl through the Eros and  the S.E.X., wow. Should have listened to Paul, wasted my time changing the pot. Thanks for the help.

Cheers,
Shawn