Large Scale Central

LGB Mikado gets RCS battery R/C

It has been a few years since I did an LGB Mikado install. Luckily I was recently given the job of installing RCS battery R/C in another two of them. One is a USA version, the other is the French version. Whilst it is possible to access the inside of the boiler without removing the motor block I have found removing the drive system makes life so much easier. I place the whole loco upside down in the packaging. This stops the possiblity of damaging the body when handling it. Be sure and put the screws and parts in bags suitably marked for later reassembly. The first thing to remove is the front truck.

Once the truck has been put to one side I then remove the front screw holding the drive system to the body.

Now turn your attention to the rear truck. Remove the screw holding the truck to the motor drive block and then the two screws either side of the motor block that attach the block to the swivelling palstic seat.

The motor block will then lift out cleanly. Handle carefully and remove the chuff and sound trigger connections plus the two wires from the motor. Remove the loco from the packaging and lay it on its side on suitable padding. Remove the hand stanchions and cab screws on either side.

The cab will lift up out of the way. As you do so gently remove the two springy wires connecting the whistle on the boiler and air control device on the RH side below the footwalk plate. Remove the handrails on both sides. Remove the small screws holding the air tanks. Some of the plumbing will also come away. Note where the parts came from.

Remove the six screws holding the boiler to the frame. Be sure and note that the two front screws are shorter than the other four.

Unplug the multi strand ribbon wire from the socket on the pcb in front of the backhead. Also, remove the LGB DCC decoder and set the four dip switches to all ON. The sound works better without it. This gives you access to the place where the R/C and ESC will go. I cut a square of styrene and glued it ot the speaker magnet with silicone roof and gutter sealant. When that was set I glued the RCS # BTL-3r decoder and motor driver pcb’s in place with silicone roof and gutter sealant.

Another view with the Hobby King RX plugged in to the decoder.

There are very few changes necessary to the stock wiring. Specific wiring instructions are available direct from RCS when I supply the equipment. However, there are a couple of ways to set up the loco wiring. My customer chose the simplest method that would allow the motor to be driven direct from the ESC output and the sound to be powered by the traction battery connected to what were the old track pick ups. This overcomes the possible “confusing” effect PWM can have on LGB sound systems. The only drawback is the polarity is fixed and the LGB electronics cannot be reversed, so the rear light will not work. I also had to add two small diodes to the backhead so the operator can see what the system is doing. The other way to do it is to power the LGB electronics via a small DPDT relay (# RELAY-1a) the coil of which is controlled by the rear lighting output of the ESC decoder. This permits the LGB rear lights to work and has the added benefit of flashing to indicate what is happening to the R/C equipment. This method will be used in the second Mikado I am doing this week. Because the RCS decoder has open collector sound triggers, connecting the LGB triggers is a simple wiring addition. NO relays or special transistor signal inverters are required. The LGB ribbon cable is plugged back into the pcb it had been removed from. It does not matter where the antenna goes. 2.4 GHz R/C is most forgiving of antenna placement and has fantastic range.

I mounted two small LED’s in the backhead that show direction set. They are unobtrusive unless you are actually looking for them. Red for reverse. Green for forwards.

The tender is only used to carry the batteries. These are Sub C 3300 NiMh 7.2 volt packs wired in series. They are fused with a 3 amp poly switch. There is a DPDT ON-OFF switch under the front of the tender floor with a 2 x wire connector cable to transfer the voltage to the loco via my standard JST connector.

I removed the lead weight as the batteries are heavy enough. No point in hauling around dead weight. The batteries are charged via a socket mounted in the water hatch.

All that was needed was to put it back together and then try it on a decent sized Garden RR. Like other LGB Mikados, this one runs superbly and the sound is as good as any on the market. Next week I will update this info with the way I went about doing the French loco. Thanks for your attention.