Digital Analog Therapy - Nationwide Repairs, Brooklyn, NYC, NY

The following tutorial is to help you with calibrating your Technics SL1200MK2 Turntable as well as the Technics SL1200MK3, SL1200MK5, or SL1210M5G pitch control back to original factory specs.

 Original Source:
Frequently Asked Questions (FAQ) Of Technics SL-1200Mk2/SL-1210Mk2 Turntables.
[Almost] Everything you ever wanted to know about your 1200 
Revision 2.2 - January 18, 1994 Copyright (C) 1993,1994 Steve Valdez < This e-mail address is being protected from spambots. You need JavaScript enabled to view it >

NOTE: The site we took this information has been on the web for years.  We discovered it back in 95', and found it again last year.  Hasn't been modified since then, but it's still an excellent reference.  We advise you to check out the page, which offers other tips, and guidelines that are helpful.  We've attempted to contact the author, Steve Valdez, but he does not respond.  His words are easier to understand then our own Technical Jabber. There are some minor revisions that should be included in his original, but we'll just make the corrections here) You'll see the Various REVISION POSTS throughout these articles).

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IMPORTANT: Make sure you have the pitch slider set at the center (0%) if you make any of the two following adjustments. 

Also, the pitch gain on one 1200 is not necessarily the same on another 1200. Or, a +6 according to the scale on the first 1200 is probably not the same speed as a +6 according to the scale on the other.

ADJUSTIMENT OF PITCH GAIN

Some have said that you can get +-15% pitch gain by doing this but on the decks that I have tried this on it doesn't get up that high. One consideration if you try this is that it gets harder to zero in on the exact speed when mixing beats.

REVISION : You cannot get the turntable to past +/- 12% by doing this modification.  Please also note, that by modifying your turntable's speed, you also mess with its drive.  Although not too common, the drive circuits have been known to short out.

Remove the top panel under the platter as described. Look at the upper right hand corner of the PCB (printed circuit board). There will be a colored pot up there (blue) which says "pitch" next to it. Use a multimeter on the pot to get a reference before turning it if you want to get back to where you started from. (test for resistance, one clip to the lead facing the back, the other on the lead to the right) Turning to the right should increase the gain (greater than +-8%) and vice versa. The pot is a little touchy when it comes to precision adjustment.

ADJUSTING THE PITCH SLIDER TO 0% AT CENTER

Contrary to (popular?) belief there is no way to lose true 0% pitch when the slider is in the middle - no matter how you hack it.  When in the middle there is a switch which is thrown which bypasses the pitch slider and the motor is now crystal locked at the exact speed. But, if your deck is messed up in this area when you move the slider in the + direction, for example, it will slow down at first and will then move to 0 and then will speed up as you move it more in the + direction! In other words you now have 0 at two places. So this is for reference if you need to get your pitch slider so that 0 is really in the center. Open up the base, look where the pitch pot is. There will be a hole about 3-5mm in diameter where you can see a small pot on the other side. Hook up a multimeter to that pot (again, connect to the center lead and the one nearest the edge of the board I think) and use a small adjustment screwdriver to adjust it to 2.7kOhm, and that's it.

CALIBRATING YOUR PITCH CONTROL TO ORIGINAL FACTORY SPECS

Part 1:
1. Set pitch Knob to 0
2. Pull out the CN102 plug from the drive PCB
3. Connect multimeter to terminals 5 and 6 of plug CN102 (+=5, -=6) on the pitch control PCB side. Adjust VR302 so that the resistance is 2.7Kohms. ± .01Kohm.

Part 2:
1. Reconnect CN102 plug back to PCB.
2. Connect frequency counter to TP27(+) and the GND(-) below it. Turn power to ON.
3. Set pitch control knob to 0
4. adjust VR301 so that frequency is 262.08kHz. ± 0.05kHz.

These adjustments have now reset the whole pitch control system back to factory spec. Failure to bring these measurements to spec indicates either worn variable pitch fader and/or pitch control variable resistor. If these are new, then the fault could lie with the the control IC, IC301.

Hers's a list of what they do...

• IC101 = Turntable Drive - Technics Part
  
• IC201 = Turntable Control - Technics Part
  
• IC301 = Pitch Control - Technics Part
• IC302 = NAND Gate - Technics Part 

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