Technics SL-1210MK2 - weird speed problem - diyAudio
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Old 1st July 2005, 01:46 PM   #1
mnsh is offline mnsh  Sweden
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Default Technics SL-1210MK2 - weird speed problem

I have a strange problem with an SL-1210MK2 turntable. Things work perfectly when turned on - rotation speed is stable, pitch control works fine, sound output is fine.

A couple of minutes after turned on and started, the platter starts "losing it" - speed jumps up and down when the pitch control is near -8%. At this point the pitch control works fine in the range -6% to +8%. The speed jumps slowly spread to the rest of the pitch control range and maybe 10 minutes after the platter is started, it is just rotating really fast.

Changing the pitch control slider with a new one (I had a spare) makes no difference. The voltage selector is on the correct setting (220V).

Any idea where this problem could be?

thankful for any suggestions,
m.
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Old 1st July 2005, 05:53 PM   #2
Netlist is offline Netlist  Belgium
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Check for bad solderings on Q201 and surrounding areas.
Resolder IC101 and IC201. If that doesn't help, Q2 and Q3, both 2SD637R, could be broken.

/Hugo
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Old 1st July 2005, 06:00 PM   #3
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Also replace all electrolytic capacitors.
I had a similar problem. It was caused by bad caps.
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Old 1st July 2005, 06:07 PM   #4
Netlist is offline Netlist  Belgium
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Hmm...even on 20+years old 1200's I never had to replace one single cap. Could you remember what cap exactly caused your problem?

/Hugo
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Old 4th July 2005, 09:32 AM   #5
burbeck is offline burbeck  United Kingdom
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hi m,
i have had this problem with that model on 2 occasions, inttermitant speed and speed suddenly increasing.
Around the motor there is a sensor /servo coil, this is a printed flexible circuit board coil that terminates in 2 vertical pins/wires soldered to the main board, at the point where the wires attach the circuit becomes broken. you will have to take out the main board to inspect this part and then it is not ovious. on one occasion the part measures ok but when assemled was causing problems, (crack in the coil).
the good news is that this part is availible as a spare from technics, sorry i cannot give you part number or drawing as i have lost my service manual.
regards
bob
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Old 4th July 2005, 10:31 AM   #6
Netlist is offline Netlist  Belgium
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Correct, and this is not easy to repair.
Here's the part number: SFMZ172-01E

/Hugo
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Old 8th July 2005, 08:11 AM   #7
burbeck is offline burbeck  United Kingdom
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p.s
has anyone got a service manual (PDF) ?
thanks
bob
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Old 15th July 2005, 09:09 PM   #8
harhaug is offline harhaug  Norway
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Quote:
Originally posted by burbeck
p.s
has anyone got a service manual (PDF) ?
thanks
bob
yes
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Old 15th July 2005, 09:16 PM   #9
harhaug is offline harhaug  Norway
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I don't know what happened to my attachment. Try this link: http://www.backspin.org/sl1200mk2.pdf

- Harald
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Old 4th September 2005, 07:44 AM   #10
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May be true what others wrote. But many years I, service Tehics ,westax, omnitronics, gemini , turntables. Many DJ's have same problems in SERBIA. The main problems is weaknes of MAGNET on botom of plate.The DJ's carring there equipmnent with large loudspeakers boxes, with stong magnets. Try to put if you can new plate. WHAT you mean about that, & the others wiseguys
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