tonearm wire identification

[marloubow]

Trying to eliminate right channel hum on a Pioneer PL-560. I have isolated the problem (I think...) to a bad solder joint at the terminal plate where the tonearm wires terminate
(no continuity before resoldering terminal, but now have continuity after resolder). I have six wires and five termination points (these become the harness pins for R & L RCA and GRND)
Here's what I have so far (hope it makes sense)

1st term 1st pin, right channel, 2 wires one green, one black. Have cont. to both right channel headshell contacts and on tonearm metal surface.

2nd term 2nd pin, right channel, 1 wire red. Have cont. to both right channel headshell contacts and on tonearm metal surface.

3rd term 3rd pin, one wire, yellow, ground.

4th term 4th pin, one wire, blue, cont. to both left channel headshell contacts, but not to tonearm metal

5th term 5th pin, one wire, white, cont. to both left channel headshell contacts, but not to tonearm metal

before I reassemble and test...does this look right? The oddball in the wiring is the 1st terminal 2 wires and the continuity I'm getting from the tone arm.
I hope this is clear enough for insight from anyone willing to help.
Thanks
martin

 

[hakaplan]

First, which was the pin that was unsoldered, that you resoldered?

Second, you list continuity, for example, to left channel headshell contacts. It has to be more specific than that. Red is right signal, Green is right ground, White is left signal, Blue is left ground. There should be no continuity between any two colors, although in some turntables the signal grounds (blue and green) are tied together, and sometimes one or both are tied to the electrical ground. If both green and red have continuity to the tonearm metal, it means they have continuity with each other, which you shouldn't have.

Yellow and black are usually electrical grounds and to my understanding, should be the ones tied together. It's conceivable that the green could be tied to black, but there should definitely be no continuity with red.

 

[marloubow]

Thanks for the response
First pin right channel.
My left channel terminal (blue for example) on the board registers continuity on both headshell pins for the left channel. Odd I know, but will recheck.
Now this is a continuity test from the harness pins to the headshell contacts with the terminal board in between.
will post again
thanks
martin

 

[marloubow]

I know this sound elementary, but no circuit from the cartridge to the RCAs should be shared...right?
martin

 

[hakaplan]

I know this sound elementary, but no circuit from the cartridge to the RCAs should be shared...right?
martin

Usually. Sometimes you'll see blue and green shared. Also the cartridge must be disconnected from the headshell wires to test continuity.

 

[marloubow]

Let's put this baby to bed.
Problem solved...turns out it was the bad solder joint as I really didn't do any other corrections. No hum what so ever.
Sweet!!!
thanks all!
Martin

 

[boreas]

Let's put this baby to bed.
Problem solved...turns out it was the bad solder joint as I really didn't do any other corrections. No hum what so ever.
Sweet!!!
thanks all!
Martin

Congratulations! Glad you got it sorted.

Meanwhile, your parts are waiting on eBay. Do a search for Pioneer PL-560.

John

 

[ghazzer]

As Howard said, make sure that you disconnect the 4 headshell leads from the cartridge before you start checking continuity of the tonearm wiring. Otherwise you will just be reading the small resistance back through the cartridge and it will look like continuity.

 

[marloubow]

Yes John, I'm watching the counter weight. Made my own feet. Could use the dust cover and hinges as well, but there's nothing like turning a $9.00 turntable into a $100.00 project that makes you second guess your original purchase.
Having said that..would you shoot me the dimensions of your dust cover? Just the footprint and height, dont worry about any tapering. May do a custom job.
Thanks again
martin

 

[boreas]

Yes John, I'm watching the counter weight. Made my own feet. Could use the dust cover and hinges as well, but there's nothing like turning a $9.00 turntable into a $100.00 project that makes you second guess your original purchase.
Having said that..would you shoot me the dimensions of your dust cover? Just the footprint and height, dont worry about any tapering. May do a custom job.
Thanks again
martin

Yup! Dustcovers can get pretty silly. Even the repros are $90 - $120. I wouldn't bid on that one unless it's still sitting on $.99 with an hour to go. Sadly, it looks like three excitable people are on the counterweight. Good luck!

My Fisher foundling measures 16-7/8" x 13-3/8" x 2-3/8". According to Turntabledepot, the online seller of repros, the original is 16-3/4" x 13-1/2" x 2-5/8". I like the reduced height better. More than enough clearance and a better profile, IMO.

John