Jelco grub screw for tonearm cable

[13Daque]

I'm mounting a Jelco SA-750L (new to me) on a Thorens turntable and I notice there's a tiny grub screw on the shaft of the tonearm. This appears similar to the grub screw on an Ittok, an arm that's much more familiar to me; on the Ittok, the screw serves to keep the tonearm cable in place. The grub screw is awkwardly placed--It's hard to put the tonearm in the collar and tighten the screw, based on where it is on the shaft--and actually appears to be a little higher than the plug of the tonearm cable, so I'm not even sure if I'm right about its purpose. The cable does seem a little loose, and I could see the plug working its way out over time. There's nothing about this screw on any of the Jelco documents I have from Vinyl Engine. Maybe I just need to take a break and take another close look at it with a clear head, but can anyone tell me about this screw and its purpose? Is it in fact there to hold the tonearm cable in place?

 

[markd51]

Don't quote me on this, but I assume just about every Jelco Arm is the same as far as Tonearm Cables, and the Mounting Shaft.

I'm thinking that this Grub Screw you speak of is not for the purpose of retaining a DIN Tonearm Cable in place, but to retain the Plastic DIN Male Plug that's fitted within the Tonearm Mounting Shaft, and what the Tonearm Cable itself Plugs into.

I've never had a Tonearm Cable fall out of either Audioquest Arm I own which are Jelco based Arms.

 

[13Daque]

Thanks, that would make sense! I would think there'd be better ways to retain the male plug in place--but maybe the advantage of this way is that it makes the tonearm easier to service. Anyway, thanks for your input.

 

[markd51]

I gather you fiddled with this screw? Do insure this screw is now properly retaining that Plug and properly tightened.
The Grub Screw should be flush to the Mounting Shaft's surface and not jutting out.

I know DIN Cables can be a little testy to get fully inserted and seated. Especially when trying to insert the Cable by lifting the Table with one hand, and going in blind with the other with Cable in the other hand.

Like I've said, I've found that when the Cable is positively plugged and inserted the Clips within the Tonearm Cable's Female DIN Plug grip very well. If yours do not, this could then be likely a fault of the Tonearm Cable used and not the Tonearm itself, which possesses 5 Male Pins, not Clips.

These arms highly benefit from high quality cables to reach their full performance potential. It can be the most important cable in the entire system.

I've always used high quality Tonearm Cables from makers like Audioquest, and Audio Sensibility.

 

[13Daque]

I didn't do much to that screw, but I backed it out in the way you described, flush with the shaft. (By the way, another confusing point: the Allen head to this tiny screw is the exact metric size as the one that's on the shaft of an Ittok.) I am pretty sure that the tonearm cable is Jelco. I will likely give the set up a test run later today, and thanks again for your assistance.

 

[markd51]

I didn't do much to that screw, but I backed it out in the way you described, flush with the shaft. (By the way, another confusing point: the Allen head to this tiny screw is the exact metric size as the one that's on the shaft of an Ittok.) I am pretty sure that the tonearm cable is Jelco. I will likely give the set up a test run later today, and thanks again for your assistance.

The purpose of that set screw is to of course retain the Male DIN Plug inside the Tonearm Mounting Shaft. it likely should be snug, but not excessively so. The reason is, is that Plug is largely Plastic or Nylon of some sort.

Should that Plug not be retained, when one would go to remove a Tonearm Cable, it's going to yank that Male Plug with it,and likely rip out the internal Tonearm Wiring.

As for the Linn Ittok. I had thought that Tonearm was made by Jelco for Linn, but I might be wrong?