Thorens 125 MK II: Need Help Troubleshooting Sound Issue with Setup

[sayhifiusay]

Gear:
Preamp: Douk Audio T4 PLUS HiFi JAN5654 Tube Preamp
Receiver: Quad Artera Stereo Power Amplifier
The new turntable: Thorens 125 MK II (SME 3009 III, Audio Technica AT160ML)
The old turntable: Technics SL-1210MK2
Speakers: B&W CM1
Headphones: Bose QuietComfort


I’ve been working on upgrading my stereo system for some time now and recently replaced nearly all components, with only a new preamp left on the list. A month ago, I was fortunate enough to get a Thorens turntable at a great price, complete with several nice accessories. When I first tested it at home, everything worked fine—sound came from both speakers, speed and flutter were spot on.

Since then, I’ve done a few restoration steps: the base plate was missing wooden trim, so I bought, painted, sanded, and attached new ones. I also added silicone oil (200,000 cps) to the trough and adjusted the levelling of the unit turning the three plastic screws underneath. However, I haven’t tested the player over these last few weeks while working on these fixes.

Today, I plugged it in, confident everything was ready to go, and suddenly, no sound from the left speaker! I connected my old Technics turntable, and it played through both speakers without any issues. This has left me perplexed because when I plug in headphones through the preamp with the Thorens connected, I get sound in both ears. If there were no sound in the left headphone, I'd suspect an issue with the RCA cable from the turntable (not original, it’s an Audio-Technica), but since the sound is fine in the headphones, where could the problem lie?

I’ve considered the RCA cable between the preamp and receiver, but my Technics turntable works fine with that cable. Is it possible the headphones are “fooling” me by combining the signal, making me think both channels are playing when they’re not? Which is unheard of, right?

Here's what I’ve tried so far:
* Applied Deoxit to the phono inputs (grounding wire and RCA cable).
* Deoxit on the tonearm inputs.
* Ordered a new RCA cable to replace the one between the preamp and receiver.


Next steps:
* Borrow an integrated receiver and test with only the Thorens in the setup.


What would you suggest I try next?

I'm a beginner with all of this, so the idea of potentially needing to solder connections feels a bit daunting to me.
Thanks in advance for any advice!

 

[twiiii]

Get a clean everhard pencil eraser and clean the contacts on the back of the head shell and the spring loaded contacts in the tube of the arm. Providing it has a removable head shell. Also check the contacts where the signal cables plug into the base of the arm.

 

[sayhifiusay]

It turned out the issue was with the anti-skate! I noticed that the tonearm was drifting away from center when lowered. I removed the anti-skate weight, and that brought back sound in both speakers. Not sure if this is a rookie mistake, but I’ll check the turntable leveling again. Running without anti-skate isn’t really a long-term solution, so I guess I’ll need to fine-tune it. Just seems odd.

 

[JonL]

In my opinion, it's unlikely that the anti-skate is the root cause of your problem. Much more likely is a poor connection someplace that reconnected as you were moving things around to remove the weight. If I'm correct, it's probable that the issue will reappear at some point, regardless of what you do with the anti-skate.