Rek-O-Kut 33H

[copterske2]

Greetings, so I picked up this turntable a couple weeks ago and everything works on it. It has what I assume to be the original fabric belt, but checking with the strobe shows it’s running spot on speed-wise. There is one issue, at least I assume it’s an issue, and that is that during transport, the tone arm dislodges from the mount as can be seen in the first picture. I can set it back in and it plays fine with no issues so I’m just not sure if there is something wrong with the mount and that the pins on the side of the tone arm should be locked into place or if it does just rest in place as is. Thanks much. for any information on this matter.

 

[gadget73]

I believe thats one of the ROK S120 arms?

Should be a screw on the side where the pivots are meant to go. Not sure if its actually a pointy screw or a cup that captures a pointy axle on the arm tube but that doesn't really matter. Likely you can loosen one side or the other up to get the pivot back in position, then carefully tighten them up until the play is gone but its not so tight that it binds. There is a very small but definitely correct adjustment point for this.

ROK S-120 tonearm rewire - pre-questions

Gots me a ROK N-33H with an S-120 arm. When I move the arm and/or touch it to play I get, what seems to be, a grounding hum and while I have a hum to set it on the record I get scratchy sounds when I move it. Once I let it go it disappears. I fiddled with the (original) RCA cable while on and...

audiokarma.org

has some better pics of all this.

 

[copterske2]

Ok I have ordered a u-screwdriver tip so I’ll give that a try once it arrives. Thank you!

 

[copterske2]

Well, now that I’m looking closer. I see that the issue is that the edge of the pivot points on the tonearm are broken. So I don’t suppose there is any other way around it, but to replace the tone arm itself. Although I suppose I could experiment with drilling a little deeper down to give the screw mount something to grab onto

 

[gadget73]

I would assume there is meant to be a cup bearing in there, not just a drilling for the screw point to sit in. A replacement arm or at least parts from a damaged one that would get what you need would do it though.

 

[Nat]

I have a Micropoise arm that had the same issue - the bearing was broken. I kludged a replacement with a bearing taken from another arm (Japanese, not TOTL, which popped out of the original arm and popped right into the Micropoise). I've never seen an issue with the replacement, though, truth be told, I haven't looked hard - I'm not one to argue with success.

 

[gadget73]

do the bearings sit into a tube that runs through the arm tube or what? Kinda looks like there is something forming the "socket" for the bearing to sit in but I can't tell exactly what it is.

 

[Nat]

My memory is clearly that the bearing was in a shallow recess machined out of the arm tube.

 

[adnick]

They look like a tiny bearing race….

 

[Nat]

Which they are - a ball race perhaps an eighth of an inch across, which is typical of arm bearings, at least in my experience. I rebuilt a Logic Datum (essentially a Syrinx Leone) which had much bigger pivot pins and races, and I was surprised by them.

 

[copterske2]

So I managed to sort of re-fashion the bearings by soldering where the edge of the races had broken off. It seems to work just fine. Now the issue I am trying to figure out is a ground hum that I can’t seem to get rid of. The turntable is grounded to the amplifier and in fact gets much worse when the ground wire is detached. It also gets worse when the motor is turned on. But gets better as the turntable is elevated, which is interesting. From some posts I have found it seems like it might be a shielding issue. Does anyone have any thoughts?

 

[copterske2]

OK, here is what worked for this particular turntable. I shielded the panel on the bottom of the plinth with foil. That didn’t have much if any effect by itself. But then through just touching the turntable in various places, I discovered that if I run the ground wire first to one of the screws, holding the panel on, that pretty much did away with the hum. Now, I don’t know if it was a combination of the foil and connecting the ground wire to the screw that did it or just the latter. But regardless it now sounds great!