Technics SL-1950 - Left channel not working / no audio

[Type2]

I am looking for some advice on where to go next. The left channel does not work on the turntable. So far, this is what I have tried:

1. Eliminated the stereo as the variable - I reversed the RCA cable on the phono input and the left channel started working and the right did not - so I know it's the output of the turntable
2. I measured the cartridge using an ohm meter - both sides registered about the same resistance
3. I removed the case and looked at the solder points on the RCA cable. A visual inspection did not reveal any frayed wires.
4. A visual inspection of the ground wire looked good as well.
5. I measured the resistance of the RCA cable from the solder points to the tip of the RCA cable and everything looks good.
6. I measured the resistance of all 4 wires from the cartridge up through the tone arm to the RCA cable.

There does not appear to be any physical breakage of the wires in the RCA cable or the 4 wires from the cartridge / stylus.

I did replace the cartridge with an Audio-Technica AT95E/HSB Headshell/Cartridge Combo Kit off Amazon.

I'm a bit at a loss. If there there something electrical going on in the turntable that is preventing the left channel from outputting audio?

Should I just replace the RCA cable anyway?

Thanks for any help

 

[Grommit]

Hi.
You say you replaced the cart , was it working with the previous cart that was fitted, or can you not try another , or even borrow another cart /headshell to try and eliminate the cart completely? Your reversing of the phonos would suggest that it was the cartridge that was at fault! IMO
I had a few issues with my Aiwa AP2200 ,but that was due to crappy rca wires breaking down

 

[Type2]

I replaced the cartridge because it came with the record player when I bought it off eBay a couple years ago and the condition was unknown. The new cartridge behaves identically.

The black RCA cable from the turntable is not putting out any signal. The red RCA cable works fine.

I reverse the RCA cables to see if the receiver had a bad left channel input on the phono input and the dead signal followed the black RCA cable. So it's related directly to the output of the turntable black RCA cable. I am just curious why I can hook up the ohm meter and test the resistance and get a clean signal - meaning there doesn't appear to be a physical break in the black RCA cable.

I'm at a loss.

 

[bluefan]

I had to replace a cable before on a Technics.. cable looked fine as well. Try playing the TT and moving the cable around.. bending it etc to see if a signal kicks in.

 

[BilboBaggins]

The problem could also be how the headshell and the tonearm couple. I’ve had a flakey headshell before. Do you have a different headshell you could try?

Did you measure for continuity between the cartridge and the rca outputs? Once you can locate the problem, it will be easy to trace. Also, perhaps you have a short?

 

[Type2]

I had to replace a cable before on a Technics.. cable looked fine as well. Try playing the TT and moving the cable around.. bending it etc to see if a signal kicks in.

Ha! Okay - so I wiggled the RCA cable and I got the left channel working so it's definitely the RCA cable that is bad. I feel kinda silly but at least I know what the problem is now. I must have had the RCA cable manipulated in a way that when I checked it for continuity it was connecting just fine. Grrrr... Sorry to waste everyone's time!

Now I need to figure out why my multiple play spindle is not working and why the arm lift doesn't drop all the way. Re: the multiple play spindle, the "fingers" on the spindle retract just fine but there is a ridge directly above that doesn't allow the records to drop. Also I have to press down the arm lift manually to allow the tone arm to touch the record.

I'll do some research on this website and I'll check out both the manual and the service manual.

Greatly appreciate the help!!!

 

[Grommit]

No need to feel bad because you misdiagnosed it !!! I had exactly the same probs with the Aiwa AP2200 I bought a while back.
Once I got the stylus down on the vinyl ok and a few other odd things , the sound was terrible on both channels!!
I put it down to the RCA plugs after doing the same as yourself ,by checking continuity on red and black ,and getting good readings I thought !!
I soldered 2 new plugs onto the cable ends and still had flaky sound , plus the soldering was a nightmare .
In a fit , I took a rca to rca lead ,cut it in half and soldered it in to the small board where the rca wire terminates .
Perfect , and what a joy some new copper wire was to solder ,rather than the flimsy brittle 40 yr old RCA copper !

Good listening . Type 2 !!!

 

[Type2]

Well I figured out why my multiple play spindle was not working - I read the service manual and I had to push the multiple play spindle downwards then clockwise. So, I just tested it and that did the trick. Next issue is getting the arm lift to drop. I think I saw a thread on that issue here - something about a 10mm copper piece under the record player that needed to be lubricated then cleaned with alcohol. I'll try to find that again.

 

[teftamaqua]

The problem could also be how the headshell and the tonearm couple. I’ve had a flakey headshell before. Do you have a different head shell you could try?

Did you measure for continuity between the cartridge and the rca outputs? Once you can locate the problem, it will be easy to trace. Also, perhaps you have a short?

Just yesterday, I put a hinge kit from KAB on my SL1200 M3D and turned it on and the left channel was not working. I went into a panic. I removed and reinserted the headshell a couple times and it started working. It just happened to be the first thing I did in the troubleshooting process. I was relieved. I sprayed the connection with De Oxit and it has been working fine. Mind you, this turntable is new out of the box 2 months ago.

I don't think the two had anything to do with each other, probably, just sitting in the box for so long led to some contact corrosion.

Hope this helps
Tim