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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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25th Jul 2021, 4:58 pm | #1 |
Triode
Join Date: Nov 2013
Location: Shaftesbury, Dorset, UK.
Posts: 29
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Technics SL-BD22D turntable with a strange fault
I have a technics SL-BD22D turntable which has a strange fault there is only 2 volts going to the motor which should be 4 volts, but if you Short the brown and orange on the multi plug it comes to life and works perfect but after about an hour or two the sound ,sounds wobbly on one channel then it cuts out and back on 2 volts and just managed to turn.
I have cleaned all controls change a couple of caps which I had. Has anyone had the same problem could be the ic at fault many thanks. |
26th Jul 2021, 12:12 pm | #2 | |
Heptode
Join Date: Mar 2011
Location: Dorset, UK.
Posts: 519
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Re: Technics SL-BD22D turntable with a strange fault
Quote:
Initially I would be inclined to monitor the +12V supply across C4 (330uF) and +6V regulated supply across C5 (47uF) to observe any voltage change when the fault occurs. A common issue with most Technics turntables of that era is dry soldered joints on the regulator IC/transistor, in this case IC1 (AN78L06) and any PCB wire links. Often saved a lot of time to just re-flow the usual suspects when in for repair. Also check power switch S1. Rich
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To an optimist a glass is half full; a pessimist half empty; an engineer twice as big as need be! |
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26th Jul 2021, 6:13 pm | #3 |
Octode
Join Date: Dec 2019
Location: Owston Ferry, North Lincolnshire, UK.
Posts: 1,689
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Re: Technics SL-BD22D turntable with a strange fault
Perhaps the +12V from connector pin 3 being shorted to connector pin 1 that in turn goes to pin 3 of Z601, is making up in some way for a missing 6V from IC1 that goes to connector pin 5 and then to pin 1 of Z601. Probably not a good idea to back feed the hall device though.
As Rich says, check the regulators and other components for dry joints and S1 the start/stop switch for being resistive contact. Dave
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Quote "All is hyperthetical, until it isn't!" (President Laura Roslin, Battlestar Galactica) |
27th Jul 2021, 8:31 am | #4 |
Triode
Join Date: Nov 2013
Location: Shaftesbury, Dorset, UK.
Posts: 29
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Re: Technics SL-BD22D turntable with a strange fault
Thanks for your help I have re done all soldering joints still no change but I will check voltage across caps and see what they are many thanks nick
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