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Sony PS-FL7II lubrication of horizontal bearing

Posted: 17 Sep 2017 13:53
by dave_n_s
I've just replaced the belts on two of these. One is behaving admirably and I really like the arm design with the optical sensor and magnetic lift on a rigid carrier with a very short arm.

The other exhibits a small bass thump every so often when the arm servos onwards, but not on every step of the linear drive. It appears that the stiction that is causing this is in the arm pivot that allows the arm to move horizontally waiting for the platform to make its next step.

The gearing from the motor via the belt to the toothed drive that pulls the string that drives the arm does not seem to allow the issue to be coming from the motor / belt end of things.

The service manual does not mention lubrication of the linear transport or the arm pivot or any adjustment of the pivot.

Has anyone dived into the fine detail of this? I've restored a lot of linear B&O tables and never seen this issue?


Re: Sony PS-FL7II lubrication of horizontal bearing

Posted: 28 Apr 2018 14:04
by racalvo
Did you find an answer to your question? I think I have the same problem.
What kind of lubricant can I use so the magnetic arm does not get stuck?

Re: Sony PS-FL7II lubrication of horizontal bearing

Posted: 29 Apr 2018 21:49
by dave_n_s
This is still in my to-do queue as I don't have a sure approach yet. I don't want to strip the main horizontal movement arm bearing (not the translation bearing) without some rationale that it will fix it.

I have been thinking of putting it in one of my systems and seeing if it clears up with frequent use.

I'll post if I fix it.

Re: Sony PS-FL7II lubrication of horizontal bearing

Posted: 04 Dec 2018 03:46
by brianb25
Interesting Dave!
I think you hit it on the spot, as I get that same deep bass thump every couple or three rotations of the LP while playing. It's driving me crazy. I too have replaced the belt on the tonearm motor with no success.

It DOES make sense that the string may be the problem. I have totally wiped down the horizontal arm, cleaned it with 409 then lubed up the horizontal bar with a light synthetic oil "Break Free CLP"; Cleans, lubricates and protects.

Not sure how or what to do with the string, as you point out. It would be nice if there were some documentation on maintenance of the string. I sure as heck don't want to replace the string.

Maybe 409 on a soft cloth to wipe it, the string, down? Probably try a very mild detergent first, i.e. soap and water? But again, one would think it might be the bushing on the horizontal bar, snagging a bit as it is being pulled.

If anyone else has a hint to remedy this occasional, obnoxious thump, you've got a captive audience :-)


Re: Sony PS-FL7II lubrication of horizontal bearing

Posted: 04 Dec 2018 04:03
by dave_n_s

I actually have a parts deck of one of these now and was thinking of changing the arm assembly, NOT the linear translating mechanism.

Watch what is happening when you hear the thump - the arm has rotated horizontally to track the groove and then appears to catch up with itself in a jump, which causes the thump. I don't think it's the case that the translating mechanism is trying to move it and failing.

Having worked on a number of opto-detection devices recently, I'm starting to think that it's the arm angular position sensing that is the problem. The LED / Opto-transistor must still be functional; I suspect I need to go back into the manual and locate the trimmer that controls the sensitivity of that circuit.

I'll post if I find the answer.

Re: Sony PS-FL7II lubrication of horizontal bearing

Posted: 17 Jan 2019 03:50
by brianb25

Thanks for the update! It was working so well after I changed the belt about 6 months ago. It is starting to stop tracking after the first song, or so of an LP. The "thump" persists even after the belt replacement.

In the meantime, I've restored my Pioneer PL-12D and it is very livable, although the rumble is still audible at higher volumes, not as bad as it used to be before I cleaned and re-greased the spindle lower assembly.

Currently rebuilding a Dual 1219 that a friend asked me to look over...

Please keep me posted as my wife LOVES the PS-FL7 and is getting a bit antsy. I will soon pull it back out of the rack to take another good hard look. Let me know what you find out about the trimmer controls for the LED / Opto-transistor!

Thanks again Dave

Re: Sony PS-FL7II lubrication of horizontal bearing

Posted: 26 May 2019 03:23
by brianb25

Did you ever get the thump figured out on your Sony PS-FL7? I agree, it seems to be the cable pulling the tonearm along that is not running smoothly. It is like it pauses for a revolution or two, maybe three, then activates and when it pulls the tonearm assembly to the next location the tonearm gets slammed into the wall of the groove it is riding in, causing the thump. If the tonearm sled moved more frequently by the motor/cable tracking it properly, we'd have the wiggle room on the tonearm riding perfectly in every groove. Other than this "Thump" it is a great liner tracking turntable.

Found a Technics SL-DL1 at Goodwill. Missing feet and the belt was totally stretched out of shape. I'll be working on this one in another post, related, if I can find some answers. It MAY be my backup to the PS-FL7.