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-   -   Technics SL-1210MK2 - weird speed problem (http://www.diyaudio.com/forums/analogue-source/60026-technics-sl-1210mk2-weird-speed-problem.html)

mnsh 1st July 2005 02:46 PM

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.

Netlist 1st July 2005 06:53 PM

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 :)

Frank Berry 1st July 2005 07:00 PM

Also replace all electrolytic capacitors.
I had a similar problem. It was caused by bad caps.

Netlist 1st July 2005 07:07 PM

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 :)

burbeck 4th July 2005 10:32 AM

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

Netlist 4th July 2005 11:31 AM

Correct, and this is not easy to repair.
Here's the part number: SFMZ172-01E

/Hugo :)

burbeck 8th July 2005 09:11 AM

p.s
has anyone got a service manual (PDF) ?
thanks
bob

harhaug 15th July 2005 10:09 PM

Quote:

Originally posted by burbeck
p.s
has anyone got a service manual (PDF) ?
thanks
bob

yes

harhaug 15th July 2005 10:16 PM

I don't know what happened to my attachment. Try this link: http://www.backspin.org/sl1200mk2.pdf

- Harald

zeonrider 4th September 2005 08:44 AM

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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