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Old 20th Jan 2021, 9:40 pm   #1
samjmann
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Default Technics SL-D210. Speed problem

Quite a long shot this. I'm after a Hall Sensor for the stator pcb on this direct drive turntable. The speed hunts up and down, worse on 33 than 45. The Hall sensors (two fitted) have 4 connections - 2 outputs, 7.5v supply and ground.

The working sensor outputs measure 1.7k between pins, and the defective one measures 3.7k between pins. Also, when running the voltage from the two connections to the servo IC is 3.9v (good) and 7.1v (bad). It's not the the servo Ic to which sensors are connected to, as both the pins measure O/C on the servo IC when disconnected.

The sensors are: OH-002 type number. I can't find any reference to this anywhere on the 'net. The sensor is surface mounted, is directly under the magnet under the turntable. See picture. The full manual is on Vinyl Engine.

The unit was made in 1984, so I'm sure all the parts are long gone now.
I've no idea what's in the sensors, they've got a 7.5v supply, that's all I know.

All the current production ones seem to have a completely different profile.

Any thoughts or advice welcome. SJM.
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Old 20th Jan 2021, 10:18 pm   #2
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Default Re: Technics SL-D210. Speed problem

A good source of hall sensors is old floppy disc drives. I had a sensor fail in a 5.25" drive which I wanted to keep working. The symptoms were vibration when rotating and a dead spot so it wouldn't always start up. I replaced the faulty hall sensor with one from a scrap 3.5" PC disc drive (ten-a-penny!) and it works fine now. The sensor was a different shape and size and, I think, sensitive on a different a is, but it worked anyway!

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Old 21st Jan 2021, 12:13 am   #3
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Default Re: Technics SL-D210. Speed problem

Thanks Chris for the reply.

I think at this stage it's pretty well 'any port in a storm'. That seems a good idea, I'll have look round.

Cheers, SJM.
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Old 21st Jan 2021, 12:30 am   #4
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Default Re: Technics SL-D210. Speed problem

Yes, anything with a sensored brushless DC motor (BLDC), so that includes computer drives (CD/ DVD floppy), VCR's, some direct driven tape decks, and other direct drive turntables.
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Old 21st Jan 2021, 11:32 am   #5
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Default Re: Technics SL-D210. Speed problem

As said, your best bet will be another donor turntable or motor. If you have a trawl through the service manuals on the Vinyl Engine website, you should be able to make a list of other models that use the same hall sensor.

Funnily enough I’m in the middle of exactly the same issue as one of the hall sensors on my Sony PS-X9 turntable has failed. Sadly this is a hugely powerful motor so its failure also appears to have taken a few of the drive circuit components with it. Luckily eBay turned up a donor motor from a PS-X5 with two of the same sensors for £20 so fingers crossed!
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Old 21st Jan 2021, 12:12 pm   #6
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Default Re: Technics SL-D210. Speed problem

Thanks John.

In the picture you've shown, the pin-outs, of the sensor shown are the same as the sensor on my deck. The supply is on the diagonal, with the two outputs on the opposite. This gives me some hope that it was a standard profile at the time.

Beobloke: I hadn't thought of cross referencing the decks that use the same Hall Sensor! I get worse...

Thanks again for all the help. SJM.
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Old 21st Jan 2021, 7:10 pm   #7
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Default Re: Technics SL-D210. Speed problem

Couple of stators here that might work (for parts).
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Old 7th Feb 2021, 8:04 pm   #8
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Default Re: Technics SL-D210. Speed problem

Success update!

Fitted a replacement Hall sensor from a capstan motor stator PCB from a Panasonic
NV-J30 VCR. Circuit ref:H101. Thanks to John123 for pointing me in the right direction. It worked first go, speed spot-on with the Lenco strobe disc. The VCR (Pana G deck) had a 12v supply to the Hall Ic's. The turntable only used 7.5v, but all seems well.

These surface mount Ic's were fiddly to fit. There was no marking as to which way the part should be fitted. No chamfered edges to denote pin1 etc. Unusually these were 4pin devices rather than the 3pin that are now available.

Thanks to all of you that have offered help. SJM.

P.S. Beobloke: Is your PS-X9 running now?
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