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Technics 1210 mkII doing CRAZY things


munamunamike

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They don't really have motors in the usual sense, the 1200 series was one of the first to use direct drive motors, and surprisingly powerful ones, able to get the heavy platter up to spped in about a quarter of a revolution, just what DJs wanted then for old fashioned cueing - scratchy scratchy stuff not even thought about then! One of the key features was a PLL speed accuracy system that constantly monitored the speed and made adjustments. The fact the deck speeds up, stops and reverses is a good indication the drive windings are fine, so the likely fault will be with the feedback sensor circuit - it thinks it's too fast, so it stops, then realises it's too slow so starts again.

 

Just a guess, but if the deck gets bumped about a fair bit - it could simply be a dry joint. The recored deck equivalent of when a moving head light loses the feedback from it's sensors and starts to wave about out of control.

 

I know this doesn't help you fix it - but it would certainly be fairly simple to open it up and have a look - and maybe if you want to fix it yourself, try doing some swaps with the other one that works well - at least then you have a pretty good chance of isolating the fault to a particular area.

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They don't really have motors in the usual sense, the 1200 series was one of the first to use direct drive motors, and surprisingly powerful ones, able to get the heavy platter up to spped in about a quarter of a revolution, just what DJs wanted then for old fashioned cueing - scratchy scratchy stuff not even thought about then! One of the key features was a PLL speed accuracy system that constantly monitored the speed and made adjustments. The fact the deck speeds up, stops and reverses is a good indication the drive windings are fine, so the likely fault will be with the feedback sensor circuit - it thinks it's too fast, so it stops, then realises it's too slow so starts again.

 

Just a guess, but if the deck gets bumped about a fair bit - it could simply be a dry joint. The recored deck equivalent of when a moving head light loses the feedback from it's sensors and starts to wave about out of control.

 

I know this doesn't help you fix it - but it would certainly be fairly simple to open it up and have a look - and maybe if you want to fix it yourself, try doing some swaps with the other one that works well - at least then you have a pretty good chance of isolating the fault to a particular area.

 

 

Interesting, the odd thng was I was using them at a party, changed the record and when I started it back up it started doing that! They have allways been flighcased and never knocked around, I have popped it opend and cannot see any obvious signs of damage/loose wires etc but will have another olook tommorow! Cheers paul..

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Im in dorset and have someone who services technics. but I wanted to know if it was something people had seen before incase it was an wasy fix.

he said he had never seen it before and if some has seen it before and rectified the problem I could just pass the details onto him!

 

Thanks tho

 

Mike

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No SL1210 is an easy fix, the board is quite fiddly to get out as it sort of half-surrounds the motor stator.

 

Most crazy SL1210 faults are caused by dry joints, there are a couple of tiny electrolytics on the motor pcb that can go s/c and I think they cause the platter tacho to become dc coupled to the motor drive IC with silly results.

 

I hope you've checked it's not full of beer.

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Probably is a bad joint leading to weird things happening to your motor.

 

Are you sure the power supply is a good clean 230V?

 

Regards, Sam.

 

I have tried it in 3 locations now so I yeah..

Also have looked inside for signs of spilleages and here is a little dust inside bit that is it..

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