SL-1401 Quartz TT with oscillating platter

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Spoke
Australia
Posts: 2
Joined: 06 Feb 2020 17:58
Location: Augsburg

SL-1401 Quartz TT with oscillating platter

Post by Spoke » 12 Feb 2020 22:23

Hi all, first post here. I'm looking for some help on the so called oscillating platter syndrome I have on my Technics SL-1401 turntable. I've only found few posts which address this oscillating issue. The platter does the washing machine forward-reverse movement after start is pressed and doesn't get out of it. It's gone into this 'mode' 3 times now. Firstly for 1 week then played perfectly again for a month till it was out again for months. Then it played perfectly for the day that I was measuring voltages, then out again for a month now. Each time the strobe is also completely out, even before hitting the start. When it plays, the strobe was always quite dim. There doesn't seem to be any other problems, not that it needs more.
Anyone know what the dim strobe is a sign of?
And which IC could cause the oscillation ? Perhaps the combination that the strobe is off, is also a sign.
Many voltages on all 3 ic's (DN860,AN660,AN640) are way off so I was looking for some pointers on where to start looking. As for parts, I was looking at a working donor board (different model)which has these ic's. There is also the russian version of the AN640 -KR1043HA7 on ebay, if anyone has tried that out?
Any thoughts about this?

Monkey_Relish
junior member
junior member
Australia
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Joined: 20 Apr 2019 12:08

Re: SL-1401 Quartz TT with oscillating platter

Post by Monkey_Relish » 15 Feb 2020 11:58

In my experience, IC’s either work, or they don’t. I would look at surrounding components.
Especially DC supplies to the IC’s. Also check transistors, zener diodes and electrolytic caps. Since it works fine sometimes, thoroughly check for dry or cracked solder joints.

Mr Relish

Spoke
Australia
Posts: 2
Joined: 06 Feb 2020 17:58
Location: Augsburg

Re: SL-1401 Quartz TT with oscillating platter

Post by Spoke » 15 Feb 2020 22:44

Thanks for the ideas! I'll get onto those first, they are the cheap things too.

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