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Old 14th Feb 2021, 11:42 am   #1
cradlefish
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Default Panasonic SG 4000 - turntable speeding up/slowing down

Hi all,
Hope everyone is well. I recently got this lovely old unit up and running with some excellent help and advice from you all. I have a new problem and I hope there is a simple solution...
The turntable has started speeding up and slowing down during playback of a record. I've got a new cartridge and new belt on this unit so don't think that's the problem. I have manually adjusted the speed as advised by the original instructions which helped a bit but the problem keeps returning. It needs a new slipmat as the original is perished - could that be playing a part? My new one is a cork/rubber blend but I don't think is as thick as the original.
Any advice or help would be massively appreciated!
Stay safe and thanks in advance.
James
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Old 14th Feb 2021, 12:06 pm   #2
Edward Huggins
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

I've looked at the Panasonic operating instructions, but I can see nothing in there about speed adjustmrnts. If you check the control electronics to the motor, are there 2 very small pre-set potentiometers, one each speed for setting the speed accuracy on 33 and 45? You can also test it out with strobe if you have one. Also double check the Belt in case it has twisted/crossed over on itself.
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Old 14th Feb 2021, 3:04 pm   #3
cradlefish
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

Hi Edward,
Thanks for your reply - the instructions to adjust the speed are in the service manual which I found after a fairly lengthy search!!! There is a white belt that also goes around the platter and seems to move a bit. When I got the player the original belt had totally perished and it took some cleaning out to get rid of it. The new belt seems to align on top of this white one regardless of where I position it. I have tried the record player without the white belt but it doesn't seem to make any difference.
I'll happily attach some pics if that helps!!
James
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Old 14th Feb 2021, 3:36 pm   #4
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

There is a very good free Android app called "RPM Speed and wow" that can be used for monitoring the speed of the platter.
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Old 14th Feb 2021, 3:46 pm   #5
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

Great! I'll try it, thanks so much!
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Old 14th Feb 2021, 10:14 pm   #6
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

i have one of these [had it from new ].Its own speakers are rubbish Hook it up to some half decent ones and you will be amazed at the difference in the sound. I had the same problem with mine some years ago .All it needed was a tiny drop of sewing machine oil on the motor bearing .its been fine ever since . Not bad for a 43 year old Unit
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Old 15th Feb 2021, 12:00 am   #7
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

Check the rubber motor supporting grommets (if fitted) have not perished - see if there is much 'side to side' movement in the motor pulley.
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Old 15th Feb 2021, 8:30 am   #8
cradlefish
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

Ah, fantastic - will give it a go! I got the system without speakers so currently have some Gale studio monitors linked up which sound great!
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Old 15th Feb 2021, 8:31 am   #9
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

Thanks Ben - I'll check.
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Old 15th Feb 2021, 9:36 am   #10
Michael Maurice
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

With the turntable off, check that the spindle bearing itself isn’t gummed up with old oil/grease.

Take the spindle out by unscrewing the securing nut on the underside of the bearing.

Thoroughly clean the surfaces of old oil/grease, including the bottom of the bearing, then apply fresh oil.
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Old 15th Feb 2021, 1:31 pm   #11
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

Great - thanks Michael. I've cleaned the spindle itself and that helped a bit. I'll try and follow your advice a bit later. Thanks so much!
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Old 15th Feb 2021, 3:50 pm   #12
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

Hi, could you please explain exactly how to get at the motor bearing? Not having any luck and am something of a novice!
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Old 15th Feb 2021, 10:24 pm   #13
Michael Maurice
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

The only motor bearing you can get to is the top one, you will see the pulley on the motor shaft, the bearing is underneath this, its where the spindle enters the motor bosy itself.

you need to dribble a couple of drops of oil (not 3 in 1 and certainly not WD40) onto that bearing.
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Old 16th Feb 2021, 8:45 am   #14
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

Thanks so much! Sorry if I am missing what is probably obvious! I got some sewing machine oil and dripped a couple of drops onto the mechanism. I then let the turntable run for a few minutes before trying a record - it was an improvement but still a bit slow/fast at points. I guess I'll need to wait a while for it to do its magic - I don't think this unit has ever had a proper service and had been in a charity shop for a good while.
If there are any other suggestions or advice - all is welcome at this point!
This is such a wonderful forum - you are all amazing!
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Old 16th Feb 2021, 9:26 am   #15
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

Is the belt too small/tight? If so that may be the problem, the belt diameter should be around 5mm larger than the diameter of the part of the turntable that it goes round.
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Old 16th Feb 2021, 9:44 am   #16
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

Morning!
I don't think so but have attached a pic. The white band you can see on the underside of the platter can be removed but it doesn't seem to make a difference.
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Old 16th Feb 2021, 10:47 am   #17
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

Stating the obvious, but have you cleaned the speed change switch? They often get a black coating caused by fumes from the rubber belts and become intermittent.
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Old 16th Feb 2021, 1:08 pm   #18
Michael Maurice
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

Quote:
Originally Posted by cradlefish View Post
Morning!
I don't think so but have attached a pic. The white band you can see on the underside of the platter can be removed but it doesn't seem to make a difference.
It wonder if it's original? I doubt it, it really shouldn’t be there. What do others think?
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Old 16th Feb 2021, 1:10 pm   #19
cradlefish
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

Hi all! Just to say that the sewing machine oil seems to have done the trick! After applying it this morning and running the turntable for a bit there was some improvement but it wasn't consistent. I left it until lunchtime to give the oil a chance to settle in and (fingers crossed) it seems to have worked its magic!
Thank you all so much for your kind suggestions and all the help you have given me.
Ever grateful,
James
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Old 16th Feb 2021, 1:12 pm   #20
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Default Re: Panasonic SG 4000 - turntable speeding up/slowing down

Quote:
Originally Posted by Michael Maurice View Post
Quote:
Originally Posted by cradlefish View Post
Morning!
I don't think so but have attached a pic. The white band you can see on the underside of the platter can be removed but it doesn't seem to make a difference.
It wonder if it's original? I doubt it, it really shouldn’t be there. What do others think?
Removing it is going to speed up the turntable, assuming the belt still makes contact with the pulleys. 50/60Hz conversion?
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