What Are We Going To Fix?
Ever since I’ve modified my turntables I’ve received nothing but compliments from DJ’s who have played on them and are amazed at the difference in handling and control. The hack in question involves removing two ‘features’ that are more of a hindrance than anything else.
YOU will be held responsible for any damage done to any equipment arising from this tutorial. If you choose to follow these tips, you do so at your own risk. Please be careful and bear in mind that if done correctly, the modifications suggested by the author can be easily undone. Good luck!!
Hindrance #1: Quartz Lock
Approach your trusty turntable but put down the screwdriver and wire cutters, we don’t want to scare the poor beast and I certainly don’t want you to do anything to your turntables until you’re finished reading this article. Now, switch it on, hit start and press your finger against the platter while watching the strobes (Figure 1) rows of dots on the platter). Notice how when you apply pressure to the platter the strobes jerk irregularly, no matter how uniform the pressure? This is Quartz Lock my friends, it is the motor of the turntable compensating for the pressure you are applying in order to return the platter back to it’s current, pitched speed. You slow it down, and it tries to speed it up. You speed it up and it tries to slow it down. These compensations are so small though that you may never have paid much attention to them, but believe me they can make the world of difference. Especially once you have experienced an SL turntable without Quartz Lock.
These dots give a true indication of current speed,
adjust the pitch slider till you see the various rows standing still.
EG: When the top row is standing still you are at (true) 6% pitch
Hindrance #2: Zero Pitch
Move your pitch slider to ‘0’ Notice how it clicks when you get there. That click, and the green light that accompanies it, signifies that you are now running at 0% pitch, listening to your record at it’s original speed. Chances are you do not own a brand new SL 1210mk2 and you have experienced the double-0 (aka argh!!) phenomenon. The argh phenomenon is a unique creature that comes to haunt us when we are at the most crucial point in a mix and accuracy is the order of the day. When the pitch control is not calibrated exactly (most of the time) you will have your true 0% pitch point somewhere between -8% and +8% and you will have a second one when your green light engages. Consider the pitch control in Figure 2 to see what I mean.
If the pitch slider is not calibrated 100% (most aren’t) then your true 0% is on either side of the green light. So, in the example above, when you’re at -1% it’s actually running @ (true) 0% and if you move it down the green light, and it forces 0%, the problem is you have two of these 0% points.
Now when you’re mixing 2 records that are of a similar speed, and the pitch on both turntables is near the dreaded green light zone (argh!) zone, then tight mixing is no longer a pleasure, it’s just bloody hard work. What does this all have to do with hacking your turntable? Yep, you guessed it. This hack will disable the green light zero pitch feature and remove the double 0% argh phenomenon from your pitch slider. It will also disable Quartz Lock so your turntables will be more responsive to your touch. Splendid!
They fixed this problem with the release of the SL MK3 turntables by removing the click in the
pitch slider, and giving you a button that you can press when you want green light on.
Get Out Your Tools – Fixing Time!
Bear in mind before we perform open-heart surgery on your precious SL’s that everything we do can be easily reversed, if you so wish’
You will need the following:
- Faith in what I’m about to tell you to do.
- A star screwdriver
- A small flat screwdriver
- A pair of small wire cutters
- A reminder note that says ‘never switch on turntable without platter attached’ ‘ NB! (This will cause irreversible damage to the motor)
Unplug your turntable and remove the platter by wedging your fingers in the two exposed holes and applying even upwards pressure. It may not feel like it’s going to come off this is just the magnet doing its thing. Once the platter is off remove the 5 screws securing the plastic cover. On the right hand side of the circuit board there is a black plug with four wires: Yellow, Orange, Red & Brown. (Figure 4) I want you to cut the Orange Wire and secure a small piece of insulating tape to each end. Leave it as is so you can reattach the wires if you ever want to. Give yourself half a pat on the back because you are halfway there and your green light (although it will still come on) will never enforce a zero pitch again.
Cutting the Orange wire.
Further down, locate the resistor marked ‘TP17’ (Figure 6) and snip it neatly with your wire cutters. Separate the two ends just enough so they are no longer touching. If you ever want to reconnect them you can drop a piece of solder on.
Disabling the TP17 resistor disables Quartz Lock.
There is just one thing left to do and that is to recalibrate your pitch slider to true 0. See that blue variable resistor marked Pitch? (Figure 5) Take note of where that is we’re going to be working with it in a moment. Replace the platter on the turntable; don’t worry about the black plastic cover for now. Set your pitch slider at 0%, start the turntable and check out the row of large dots. Are they moving in either direction? Your next and final step is to adjust that blue pitch pot until the row of large dots is standing still. I advise making very small adjustments and then putting the platter back on to see the results. If you are into these sorts of things already and you happen to own a Multimeter I believe the original factory setting for this resistor is 2.7kOhm. Otherwise it’s a matter of patience and trial-and-error. When you’re finished calibrating, re-attach the plastic cover followed by the platter and Gavin’s your father’s brother!
If you decide to go ahead and do this hack then I would appreciate it if you would leave a comment with feedback and tell us how you like the hacked and improved Technics SL1200 mk2. This hack is not for everyone, so proceed with caution. I will certainly never forget the looks on the faces of my friends when I told them what I’d done to my beloved decks. It was a mixed expression of shock and horror, followed by the slightest hint of curiosity regarding the outcome. It didn’t take them long, 1 or 2 mixes and they had the Aha Moment, a realisation that this wonderful machine we have come to cherish can be made even better.
(Originally written and posted by Wayne Ellis Lee on November 2 / 2003)