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Old 21st Nov 2016, 6:27 pm   #1
nigelr2000
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Default Technics SL-Q30 Direct Drive Turntable

This has been sitting around for ages but I got round to playing with it today.
The fault was when you powered it up it made a hummy noise and ran slowly backwards pulsing the drive in sympathy with the hum.

I looked close at the 2 hall effects and saw one had some very tiny bulges on the top. Quick look in the spares pile revealed an old JVC linear tracker with broken cabinet and direct drive turntable so i stripped it to find the halls were 4 pin out of one end like a transistor unlike the technics where they emerge from each end like an IC, also no pinout information available in the service manual but with nothing to lose I connected it up, same symptoms so I rotated it 180 degrees, still no effect I then turned it over re-soldered it in stuck the platter on top and was amazed to find it running and at the correct speed. What a result, just goes to show they are quite robust devices as you can insert them the wrong way round and wrong way up !!
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Old 21st Nov 2016, 7:34 pm   #2
unitaudio
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Default Re: Technics SL-Q30 Direct Drive Turntable

The repairs you don't expect to work are always the sweetest when they do!

Regards,
Paul
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Old 22nd Nov 2016, 12:16 pm   #3
ben
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Default Re: Technics SL-Q30 Direct Drive Turntable

Wonder what caused that sensor to fail? I'd associate bulges with some short/overheating, I would have thought though that the voltages used in such a circuit would be negligible....
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Old 22nd Nov 2016, 12:55 pm   #4
Lloyd 1985
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Default Re: Technics SL-Q30 Direct Drive Turntable

Nice work! I've got a Sony PS-Q7 on the to do pile with a dead hall sensor, I tried some from computer fan motors, bit they just were not right! Borrowed one from one of my Technics Sl-5's and it ran fine, one day it'll get fixed!

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Old 22nd Nov 2016, 8:45 pm   #5
nigelr2000
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Default Re: Technics SL-Q30 Direct Drive Turntable

Ben, I think it had been got at as there were a few screws missing and the hals are open to the world so if the platter was put on with it powered it might just have been shorted by the metal centre spindle

Hi Lloyd I have done a bit of research and I think the one I used is one of these
http://www.allegromicro.com/en/Produ...hes/A1233.aspx and they show as still available
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