Hello, markliners.

How would you go about connecting a 7186 turntable (not 7286!) to the 7687 decoder?

The decoder box does not contain a ribbon cable. The 7186 does not have a ribbon cable. The connection diagram in the decoder and the 0308 digital book show a ribbon cable.

Thanks and best regards,

Tony

I am not aware of any feedback from any Turntable.

The output of the 7687 to the 7286 is analog and one-way as far as I know. Do you have any evidence of digital feedback? How does the TT even know where the bridge is? There are no position sensors.

As others have pointed out the two turntables use different motors. The 7286 uses a DC motor, so if the polarity to the motor is reversed the motor will turn the opposite direction, allowing the turntable to turn either direction.

The 7186 turntable has a "universal" motor which will run on AC or DC - but with DC unless you reverse the current through the magnet it will always turn the same direction (irrespective of the DC current direction) - which is the reason it will also run on AC.

The motor as fitted to the 7186 turntable uses standard loco motor parts, so what you COULD do is use a loco upgrade kit to change the field coil magnet to a permanent magnet, and fit a 5 pole armature. I would recommend changing to a 5 pole rotor as this may be needed to get the current low enough for the 7287 decoder to handle, the motor in the 7286 is quite small and geared well down, and I don't know what the current carrying capacity of the 7287 is.

You may then need to look at the release solenoid, to see if the driver for that has enough grunt. Again the solenoid in the 7286 is quite small. At worst it may be necessary to rewind the solenoid with more turns of finer wire to get the current low enough, but there is a trade off when you do this. It may be better to have the decoder operate a relay that then drives the solenoid.

Hi Antonio,

Don't use the 7867 with the 7186 TT as you will destroy the stepper motor control in the device.

Use a m84/k84 device to replace the push button panel.

The motor in the 7286 turntable is an ordinary DC motor not a stepper motor. The decoder just times how long it expects to take for each track increment, then releases the solenoid which cuts of the motor when the solenoid lever indexes into the drive gear on the end of the turn table bridge. The only form of feedback that the decoder can get is sensing when the current drawn by the motor is turned off when the bridge indexes at the next track.

Definitely a DC motor.



If it is anything like the LDT controlller it is a dual half bridge controller, which when driven with appropriate waveforms can drive a stepper motor, but by driving the two inputs appropriately makes a good DC motor driver.



I don't believe it does, I suspect it is like the LDT one and does it purely on time since it was actuated. The LDT one has a potentiometer to set the speed to allow for variations in motors (it will also handle the SB motor).

Hi Alan/All,

The motor is DC and my reference to a stepper motor control is not the type of motor but a simple term to explain how it counts the number of steps to locate the correct position.

Tom (torle) explained it well.

The bottom line is if the the 7687 decoder is wired to the 7186 turntable there is a great chance that the decoder will be destroyed.

I like to convert old analog stock to digital operation. Posts about the 7186 turntable were not working for me, but here is my solution.
The primary issue is digital power vs old AC power to turntable, while also controlling the k84 decoder. The turntable will not function with digital power, so the yellow lead must come from an accessory transformer that shares ground with track (or turntable ground).
The k84 is needed for left/right turn (#4) and the long pulse (#3) to get going; k83 for solenoids won't allow control. Importantly, once the k84 unit gives a start pulse it needs to be turned off. The turntable will continue to rotate (with less noise) and stop at next closest track (just like old manual switch does).
The k84 start and stop is easy to program in cs3, but is manual for older intellibox. Maybe there is a more clever solution to stop pulse in older digital drivers.
Pic of k84 connections is below. Yellow and white go to accessory transformer; red and brown to digital power. This works for me.

Since the request was for a 7186 I would stick to the original product!!!

This is what I found in the Marklin Digital booklet.

You need an M84 or the components shown in the picture.
I recall Marklin telling me that the m84 is better to manage the 7186, compared to the m83

2 x 7245 universal relays
1 x K83
1 x S88 if you want to program the tracks (to me useless)

I have managed to get the crane to work in this same configuration, more or less.
HTH
Marco