I therefore decided not to drive my turntable using the 7687 decoder. Since I am using a PC to control my layout I decided that it would be simpler and more reliable to use a simple k84 type module to control the turntable. These pictures show how I did this.
The manual controller that comes with the turntable provides the plug interface to the turntable and a rather pathetic direction knob and on / off button to stop and start the turntable...
open up the case...
and note the bridge rectifier. We use this rectifier so simply desolder the 4 legs of the rectifier...
I positioned a Viessmann 5213, the rectifier and the turntable plug on a wooden base..
and wired it up as can be seen in the picture. 2 of the 4 switches are used to reverse the polarity of the DC current produced by the rectifier. A third switch is used to switch the stop/go signal for the turntable to be the same as one of the motor polarities. One rail plug of the turntable plug is left free for a s88 port to detect occupation or it can be grounded also. All the new module needs is one ground, one digital and one power supply to be connected. I suggest that you run the yellow power supply through a manual override switch. You can also connect an optional s88 line.
Here is the schematic I use in my software to define the k84 addresses to use for the turntable.
I used a spot of hot glue to hold the bridge rectifier in place.
I plugged it all in, added some lines of code to the program and it all works !
Here is a comprehensive description of how the Märklin 7286 turntable works.