1200 MK2 -- wacky pitch control, requesting advice from an expert

[hatertot]

I'm pretty bummed.

I have a couple old 1200MK2s that I've been working on. Both turntables have an issue:

Pitch control is very inconsistent, and seems to operate on a wacky curve. They are perfectly calibrated for +/- 8 pitch range, and their zero-points are spot on, however there is a weird curve. For example, sliding from from 0 to +1, the pitch increases from 0 to .5%. Then from +1 to +2, it goes from .5% to 2.2%. @ +3 on the slider, + 3.5% speed, and so on until at +7 on the slider, it plays at +7.5%, then at +8, it goes back down to a correct 1:1 slider position to percentage speed ratio. There are a few very specific ranges on the slider where the pitch increases very dramatically at the slightest adjustment of the pitch fader.


A couple notes for anyone who is still reading and considering responding at this point:
- I am using Traktor Scratch's on-screen readings to give me what +/- speed the control vinyl is playing at. I have every reason to believe it's accurate because I compare the 4 different reference speeds at which you're supposed to check the strobe dots, and everything checks out (e.g. the zero platter dots are still @ Traktor saying we're at 0% pitch difference)

- I've performed the no-zero-lock mod (clip orange wire) as well as the quartz lock mod (clip the resistor), and I believe that I should be able to expect near linear pitch control regardless -- all i've done with these mods is remove all overrides that inhibit the pitch fader having full control over the speed of the platter.

- I've replaced one of the pitch faders with a brand new one. This actually did help significantly but the problem remained. Specifically, in the +0 to +8 range, it was 1:1 linear, but in the 0 to -8 range was still really curved.



1200 experts, i beseech you for your advice. Have you seen this issue before? I'm thinking the only thing left for me to try would be new pitch control boards and then even maybe a new master logic board

[DjLiquitATL]

Make sure the pitch control cables are not squashed by the cabinet when you put everything back together... Also the zero point fluctuates when Quartz lock is disabled/removed. You will have to spend a lot of time getting pitch perfectly calibrated back to factory settings

You did clip the tp17 resistor right? And cut the orange wire?

Pitch should be good. Don't go off TSP readings... Look at the dots...they should move smoothly and if there are any issues with pitch you can see the platter dots go out of wack

Now sometimes platter magnets get messed up which could also be the issue... I had to replace a platter about a month ago bc my pitch was all out of wack similar to what you described

Also make sure you set both pitch controls the exact same calibration

[hatertot]

the platter eh? That's sounds like a much better lead to me than the entire main board. Thanks a million!!

[angel1092]

You need Mk2 Timecodes.