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Thorens TD166 MKII Right Channel Distortion

C

croches

New Member
Hey everyone! I've been trying to get an old Thorens TD166 MKII working again but I have persistent distortion in the right channel that I can't seem to diagnose. At this point I'm wondering if it's an issue with the cartridge, but curious if anyone has any better ideas of how to proceed before I buy a replacement.

Turntable: Thorens TD166 MKII w/ a TP63 Tonearm (I believe)
Cartridge: Signet TK7Ea
Stylus: AT VMN20EB (stylus is brand new)

Here's a list of things that I've tried:
- Swapping RCA cable connections at the receiver (Left to Right and Right to Left): Distortion moves from right channel to left channel. Don't think that my receiver is the issue, because it works perfectly fine with another turntable.
- Continuity testing with multimeter: I have continuity from the cartridge (Red, White, Blue and Green) all the way through the RCAs.
- Replace RCA ends: Have replaced RCA ends with new RCA ends. No change.
- Cleaning stylus: Cleaned the tip of the stylus, no change.
- Swap wiring on cartridge (Red to White, Blue to Green etc): This moves the distortion from the right channel to the left channel, which is what makes me think it's potentially an issue with the cartridge. I tested the cart with a multimeter and everything seems to be in spec, so not sure how else to know if the cart is bad.

Any thoughts would be much appreciated. Thanks!
 
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all signs point towards a problem at the cartridge or stylus end of the chain since swapping the wires at the back moves the problem. Maybe being grossly out of alignment could do it? seems odd that it would only be in one channel though. Stylus I'd think would be in both channels but I suppose its possible to have one be messed up in a specific way that only affects one channel. Think it would have to be something with the magnet itself being out of position though, unless somehow the rock on the end was damaged on one side only.
 
Yeah, I have a feeling it’s the cartridge…was just hoping it would be something simpler/cheaper. Maybe I’ll try to find a cheap cart to test to see if that’s the problem.
 
Anti skating? Too little or no anti skating could give right channel distortion.
Downforce? Shall be 2 g +/- 0.2 g with that stylus.
 
Just tried adjusting the anti skating across the spectrum (although the anti skating instructions in the manual are a bit confusing, so not entirely sure I’m doing it correctly) and played around with some additional downforce, but neither made any discernable difference. I ordered a cheap cart on Amazon for $15 to see if the distortion persists before I commit to replacing with a decent cart. But still open to other ideas.
 
croches said:
Just tried adjusting the anti skating across the spectrum (although the anti skating instructions in the manual are a bit confusing, so not entirely sure I’m doing it correctly) and played around with some additional downforce, but neither made any discernable difference. I ordered a cheap cart on Amazon for $15 to see if the distortion persists before I commit to replacing with a decent cart. But still open to other ideas.
Click to expand...

At that price the new cartridge might be suspect as well. Might have wanted to try AT's cheapest, I believe it's around $30.

Most likely neither will be a good match for the arm on the TD166MKII, it prefers a higher compliance cartridge like the old Pickering XV-15.
Screenshot_20231128-153915.png
 
Thanks for the feedback! My hope was that even if the cheap cartridge performs poorly, it will at least help me distinguish (cheaply) whether or not there is still distortion isolated to the right channel, at which point, I can make a decision about whether or not to buy a better cartridge. Do you think the extra $15 is worth spending on that AT cartridge if it's purely for testing?

I had reached out to AT about what current lineup cartridge would be a good replacement for the Signet and they suggested the VM520EB. Just didn't want to get stuck with a $135 cartridge that didn't fix the issue.

Appreciate the link for that stylus too! Will definitely keep in mind if I find the cart is still functional.
 
While I wait for the test cartridge, I just tried using Seb's Thorens Baerwald Arc Protractor to see if maybe it was a cartridge misalignment issue...no improvement. Played around with tracking and downforce again, and still no improvement.

This may be a dumb question, but is there any way to clean a cartridge? Like could there be something in the cavity of the cartridge that could be causing distortion? I'm remembering that when I replaced the stylus, one of the magnets from the stylus was broken off and sitting magnetized to the inside of the cart. I used tweezers to carefully remove it, but wondering if there could be any other junk in there. Anyone with experience trying to clean out a cart? Would it be risky to try spraying some air in there?
 
Your troubleshooting is on point. If it's not your cartridge/stylus it's a gremlin.

Carts do fail, it's just not very common.

Have you removed the stylus and checked inside the cart opening and stylus suspension? Possibly the stylus has issues? I think these have magnet on the back of the cantilever, maybe one fell off?

If your stylus is good, I would seek out another Signet, as it seems you have no other reason to change your setup. You should also be able to find a new budget priced stylus that will fit your Signet, for testing in that direction as well. Sadly, getting the same quality stylus and cantilever will not be so budget friendly...
 
And this is why I love these threads. Sometimes all it takes is a little back and forth, and just writing things out to figure out the problem.

As I mentioned in my last message, when I'd recently installed a new stylus, I'd noticed that one of the magnets had fallen off the old stylus and stuck to the inside of the cartridge. I carefully removed it and moved on. Well I just inspected the inside of the cartridge with a flashlight and magnifying glass and found another magnet stuck on the inside, so I removed it and...the right channel is now back in action!

Frustrated that I had to go through so much troubleshooting to come back to something I should have probably noticed from the beginning, but thank you all for bearing with me and throwing out suggestions. Not sure if I would have remembered about the magnet issue from before without the back and forth.
 
Cool, glad you got it sorted. Guessing the stylus is the kind with a pair of teeny magnets glued to the cantilever in a V shape where it goes up into the cartridge body?
 
@gadget73 Thanks! And yes, you're exactly right about the stylus. Not sure how they got dislodged/broken, but since they're magnets they clearly sucked up into the cartridge instead of just falling from the stylus.
 
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