Seeburg USC2 Thumping Noise When Record Spins

My USC2 has a loud thumping noise when the record spins. Sounds like a heart beat. This happens more with some records than others. Would this be a case of adjusting where my arm sits on the mechanism? Maybe a ground issue? I think the sound happens more depending upon how warped the record is. Not sure where to look for this one.

It has a set of new stylus installed. Records are clean.

Thanks for your help.

Check, and if need be, adjust the stylus pressure adjustment(s).

Well, I adjusted the stylus pressure and it didn't really do much. What does get rid of it is if I touch my fingers and put just a little pressure downward on the two screws on the arm of the thing that goes into the record to spin it.

My advise would be to unplug the jukebox from the wall, look at the "stickies" posted above, for where to find/purchase, a service manual, so you can at least ID whatever you are "pushing on". At that point, re-post here, and someone will most likely be able to understand the problem and suggest a fix. As it stands now--that "thump" may be causing expensive damage. Ron Rich

Ok, thanks Ron. I do have the service manual and should have been more specific in my post.

The part that I push down on very slightly that makes the thumping noise go away are the two screws on the pivot block on the clamp arm. I have adjusted the pivot block but that does not help the noise go away. Just slight pressure down on those two screws with my fingers makes the thumping noise go away.

Not sure if this means the clamp arm needs adjusting?

In this case, I would first check the turntable thrust bearing adjustment. If in spec., I would check the clamp arm spring--if "over-stretched", IMHO, it MUST be replaced. After that, yes, if someone has "re-adjusted" the clamp arm, it may have been done incorrectly (of course, that would be the "first time" anyone heard of that !! ) Ron Rich

Well, I adjusted the three screws on the centering pin position clamp arm with locking nuts and now the record runs into the tone arm when loading side 2 of the record. Is that something related to the centering pin position or does the pickup lifting need to be adjusted again?


EDIT: Nevermind, I figured this out. I had to adjust the bushing screw on the left side of the mechanism when looking at it from the back. Now it has clearance to load the record and the arm gets out of the way.

Well Ron, you pointed me in the right direction again. The clamp arm spring was worn out. It had obviously been stretched and snipped at some point. The spring had a gap in the middle and was balancing on the little plate it is SUPPOSED to be hooked around! Went to the hardware store, got the right spring and now, no more thumping.

Hope this helps someone else out in the future. Kind of tricky to hook the spring back up, but it came together. Again, thanks Ron for your help.

Torin

Torin,
Glad it's fixed--but gotta dis-agree--it was NOT "worn out"--it was "vandalized"--Hint, If you ever need to hook/unhook one, hook it on the casting first, with the clamp arm in play position--no record in the slot, use a "spring puller" to pull it through the clamp arm, onto the holder. Ron Rich