My Märklin 7286 turntable was not moving so it was long overdue for a service. While I did that, I also decided to do some upgrades to make it work better than before.
I describe here how I carried out the following upgrades:
- Improved rotation
- Improved electrical contacts
- Added lighting to the control shed
- Added control desk direction indicators
- Added an operator in the control shed
The turntable bridge pivots about on a central support ("Königsstuhl") which has some concentric contacts. These contacts needed cleaning so I rubbed them with a very fine sandpaper and also cleaned them with some contact spray applied with a cloth.
I also cleaned the finger contacts on the underside of the bridge that ride along on the contacts:
Despite good contact on the supporting side, I could not get one of the running rail contacts to work, despite bending the finger downwards to apply more pressure, so I gave up and soldered a wire between the two rails.
It always annoyed me that there was no light in the control room, so it was time to fix that. The shed unclips from the bridge providing good access to the interior. The glass windows are made from a single translucent piece that has a small dimple in the ceiling, a perfect size for adding a surface mount LED.
First I looked closely at the LED with a magnifier to determine which wire was connected to the end with a small dot. This is the side that has to be connected to negative. I tied a small knot in the other end of that wire.
I taped the LED into the top and ran the fine wires to the the corner of the building .
I then inserted the glass into the shed, keeping the wires between the glass and the outer frame at the corner so they cannot be seen.
There is enough room in the hole that the building clips into, to pass the two wires through to the underside of the bridge without having to drill a hole.
I decided to power the light using the power from the track as I did not want it only going on when the turntable was moving. Since the track contains the digital signal, it is AC and thus needs a diode to only allow the current to flow in one direction, plus the usual protection resistor.
The rails provide one side of the power source for the light, so I needed to get power from the center rail. I soldered a wire onto the small contact that conducts the center rail current to the parts between the tracks:
I drilled a small hole next to where the contact sits:
A quick test showed the light worked well.