Technics SL-23 turntable slowing down over time

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pcoleff
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Technics SL-23 turntable slowing down over time

Post by pcoleff » 18 May 2019 13:18

Hi all,

I recently got technics SL-23 at the thrift store. I replaced the belt on it, lubed up the pitch knobs, and speed switch, as well as put a new stylus on it. I noticed, though, that even when the pitch knob was turned all the way to +, it was still playing slow. I tried opening it up and adjusting the variable resistor and that made it so I could get it to the correct speed. But it's still slowing down. Basically, what happens is that it starts a little fast, then gradually gets slower. This is independent of the tonearm's place on the record. So it'll get slower and I can bring the tonearm back to the beginning of the record and it'll still be slow. Then, if I turn the turnable off for awhile and start it again, it'll go back to the previous speed, but gradually start slowing down again. Any suggestions as to what to do? I thought maybe that the motor would need some oil, but the service manual basically says that that motor doesn't require oil and doesn't tell me what kind I should use. Thank you for your help
Patrick

Alec124c41
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Re: Technics SL-23 turntable slowing down over time

Post by Alec124c41 » 18 May 2019 15:06

After ~40 years, a bit of oil will help. A drop of sewing machine oil to the motor shaft, under the pulley, will run into the bearing. Also get a few drops into the spindle bearing, under the platter. Ideally, you would remove the spindle, and clean out the bearing well, before adding fresh oil.

Cheers,
Alec

totem
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Re: Technics SL-23 turntable slowing down over time

Post by totem » 18 May 2019 17:16

The SL-23 has a known issue along with others, regarding the speed adjustment pots.
By lubed did you mean cleaned? You would have to get at them from the bottom and not a spray
from the top.

lenjack
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Re: Technics SL-23 turntable slowing down over time

Post by lenjack » 18 May 2019 20:06

What do you mean by lubing the pitch knobs? You didn't oil them, did you? That's a no-no. If you meant cleaned with contact cleaner, that's OK. If oiled, I think they need to be replaced.

pcoleff
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Re: Technics SL-23 turntable slowing down over time

Post by pcoleff » 18 May 2019 21:02

No, I didn't mean oil in the pots. I used deoxit, the same stuff I've used on my keyboard pots. They seem to be working well. In fact, they are operating a lot better than before I cleaned them. I've bought some sewing machine oil, as recommended by this board, to try and lubricate the motor shaft and spindle.

lenjack
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Re: Technics SL-23 turntable slowing down over time

Post by lenjack » 18 May 2019 22:33

If you haven't used the oil yet, get yourself some of this Technics oil.https://www.kabusa.com/frameset.htm?/

Van_Isle
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Re: Technics SL-23 turntable slowing down over time

Post by Van_Isle » 19 May 2019 06:05

That Technics oil is not necessary (nor probably desired) for a Technics belt drive. Direct drive ... yes for sure. For the SL-23 with the standard bearing-well style spindle, a light oil like the sewing machine oil is just fine.

I've had to disassemble the 45-off-33 switch on these tables to get them clean ... and that had a huge impact on steady speed.

That approach can't hurt (unless parts of the switch are lost / damaged / reassembled incorrectly) ... however with this situation I'm wondering if failing capacitors and / or failing variable resistors (internal trimpots) are causing the problem?

lenjack
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Re: Technics SL-23 turntable slowing down over time

Post by lenjack » 19 May 2019 16:33

Yes, there may be internal trimpots.

Van_Isle
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Re: Technics SL-23 turntable slowing down over time

Post by Van_Isle » 19 May 2019 17:40

lenjack wrote:
19 May 2019 16:33
Yes, there may be internal trimpots.
I can assure you there are trim pots in the SL-23. OP did adjust them (post 1). Clearly identified in the service manual.

Electone
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Re: Technics SL-23 turntable slowing down over time

Post by Electone » 24 May 2019 00:19

The SL-23 came from the factory with a dark grease in the spindle bearing well. I have yet to service one where the grease had hardened (unlike JVC and Pioneer). But, it's still a good idea to clean it all out and replace the grease with fresh oil. Beware not to lose the tiny ball bearing at the end of the spindle.

Melbourne_calling
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Re: Technics SL-23 turntable slowing down over time

Post by Melbourne_calling » 25 May 2019 17:39

Hi, a friend recently had a very similar problem with his Technics SL-23. i.e after cleaning the pots with a contact cleaner, it still wasn't holding correct speed. I suggested he read this short article written by someone in a similar predicament, and their solution to the problem. Basically he changed 5 or 6 electrolytic capacitors in the speed control section as suggested in the article, and it cured the problem.
Here is the link to the article
http://www.artandtechnology.com.au/audi ... -sl23.html
good luck with it, hope it helps.
cheers

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