Auto return = skating across record - eek!

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freestyle_gus
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Auto return = skating across record - eek!

Post by freestyle_gus » 12 Jun 2019 11:00

My recently acquired, slightly crusty Sansui P50 is now running pretty nicely. It actually sounds very good.

BUT. Now that I have properly balanced the tone arm (horizontally zeroed with the platter) the autoreturn doesn't elevate the arm high enough and skates the stylus across the record(!) Which makes me feel rather sick to see :shock: (and I assume long term will damage my stylus?)

Manually raising the arm works fine.

If I balance the arm slightly higher than horizontal (counterweight is further back on the tone arm) it does seem to work (I can use a scale to get the tracking force correct) again. Is this technically a solution? Am I missing something, that may cause me a problem?

I think the problem is old springs are stopping the arm riser going high enough...

My other solution was to add a thin layer of sugru putty to the rubber riser track to bulk it out...

I'd love your opinions on how you'd solve this. Please bear in mind I'm not very technically minded!

:D
Last edited by freestyle_gus on 12 Jun 2019 11:08, edited 1 time in total.

Solist
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Re: Auto return = skating across record - eek!

Post by Solist » 12 Jun 2019 11:05

I had the same problem, another turntable, but same issue.

Yes, it will damage the stylus, cantilever and record. So fix it asap.

Check if you can find a manual. The same mechanism should be used on other models, so some research would be welcome. If you cant find anything, then the only option left is to trying to figure it out by observing the mechanism and look for parts that are stuck. The problem is that the lever which raises the tonearm at the end of the record is stuck, or one part of that mechanism. This will cause the tonearm to not elevate fully resulting in what you experience.
Last edited by Solist on 12 Jun 2019 11:10, edited 1 time in total.

freestyle_gus
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Re: Auto return = skating across record - eek!

Post by freestyle_gus » 12 Jun 2019 11:09

Solist wrote:
12 Jun 2019 11:05
It had the same problem, another turntable, but same issue.

Yes, it will damage the stylus, cantilever and record. So fix it asap.

Check if you can find a manual. The problem is that the lever which raises the tonearm at the end of the record is stuck, or one part of that mechanism. This will cause the tonearm to not elevate fully resulting in what you experience.
Many thanks.

Sadly there are no available manuals for this one :cry:

Solist
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Re: Auto return = skating across record - eek!

Post by Solist » 12 Jun 2019 11:11

The same mechanism should be used on other models.

freestyle_gus
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Re: Auto return = skating across record - eek!

Post by freestyle_gus » 12 Jun 2019 11:12

Solist wrote:
12 Jun 2019 11:11
The same mechanism should be used on other models.
Good idea, I'll have a look!

freestyle_gus
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Re: Auto return = skating across record - eek!

Post by freestyle_gus » 12 Jun 2019 13:15

The SR232 and SRB200 look to be cosmetically the same.

I can't see anything definitive in the service manuals.

musicmn
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Re: Auto return = skating across record - eek!

Post by musicmn » 12 Jun 2019 18:17

Hi freestyle_gus, I checked out some pictures of that turntable on the web but I could not get a good look at the cue elevator. You may just need to adjust the cue elevator height for your current cartridge. Some cue elevators have a screw in the middle of them that pops up when you manually push down on the elevator. If your cue elevator is designed like that first cue the elevator to the up position. Then manually push the elevator down and the screw should pop up. Turn the screw counter/anti clock wise to raise the elevator. Then test the tonearm return to see if it's high enough. Keep adjusting the elevator height until you get correct. On some cue elevators there is a small set screw on the side of the cue piston that is used to raise the elevator. Just loosen the screw raise the elevator to the height you need and tighten the screw then test. Hopefully this is all you need to do to fix this issue. Now if adjusting the cue elevator height does not work to resolve the issue with the tonearm dragging across the record then my guess is that the silicone damping fluid used on the cue piston has thickened with age. Once the damping fluid gets to thick the lever that pushes the cue elevator up can't do it fast enough and the auto return kicks in and you have the dragging issue. If this has happened the only way to fix it is to disassemble the cue control mechanism and clean out all old damping fluid. In put new 300,000 wt silicone damping fluid on the cue piston and assemble the mechanism. On some turntable models getting to the cue piston can be a challenge because it's buried under the main mechanism. On other models it can be very easy to service. Again with no service manual or experience with this model of Sansui turntable I can't give you any more pointers on how to proceed. But I hope something here helps.

freestyle_gus
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Re: Auto return = skating across record - eek!

Post by freestyle_gus » 12 Jun 2019 18:24

musicmn wrote:
12 Jun 2019 18:17
Hi freestyle_gus, I checked out some pictures of that turntable on the web but I could not get a good look at the cue elevator. You may just need to adjust the cue elevator height for your current cartridge. Some cue elevators have a screw in the middle of them that pops up when you manually push down on the elevator. If your cue elevator is designed like that first cue the elevator to the up position. Then manually push the elevator down and the screw should pop up. Turn the screw counter/anti clock wise to raise the elevator. Then test the tonearm return to see if it's high enough. Keep adjusting the elevator height until you get correct. On some cue elevators there is a small set screw on the side of the cue piston that is used to raise the elevator. Just loosen the screw raise the elevator to the height you need and tighten the screw then test. Hopefully this is all you need to do to fix this issue. Now if adjusting the cue elevator height does not work to resolve the issue with the tonearm dragging across the record then my guess is that the silicone damping fluid used on the cue piston has thickened with age. Once the damping fluid gets to thick the lever that pushes the cue elevator up can't do it fast enough and the auto return kicks in and you have the dragging issue. If this has happened the only way to fix it is to disassemble the cue control mechanism and clean out all old damping fluid. In put new 300,000 wt silicone damping fluid on the cue piston and assemble the mechanism. On some turntable models getting to the cue piston can be a challenge because it's buried under the main mechanism. On other models it can be very easy to service. Again with no service manual or experience with this model of Sansui turntable I can't give you any more pointers on how to proceed. But I hope something here helps.
All good advice, many thanks!

I'm going to have some time tomorrow to check through these suggestions. Fingers crossed!

freestyle_gus
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Re: Auto return = skating across record - eek!

Post by freestyle_gus » 12 Jun 2019 20:23

Okay, so I had a chance to get the bottom off tonight and I've diagnosed the problem.

The arm lifter is set into a plastic peg, this is beveled into a point at the bottom and is actuated from below by a metal plate when the autoreturn kicks in.

Unfortunately on this old TT the point of the peg has been worn down enough so that it's not being pushed high enough. So, I think I need to bulk up either the bottom or the top of the lifter, the top probably being the most reliable but least aesthetically pleasing fix.

Anyway, it's pretty clear the arm lifter on the P50 isn't adjustable, at least not as far as I can see.

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