Beautiful Tillig locomotive, such as BR189 OBB, it would be pity having no sound. When opened, I realised quickly there is simply not space between inner roof (PCB) and the inner mechanics of chassis to fit the standard loadspeaker. Instead, I had to buy a set of 2 smaller ones in round shape, which would fit exactly under the PCB at each end.
First thing is to document original state of wires soldered to the PCB, as we need to get them disconnected and take out the PCB.
In order to accomodate the decoder itself, there is not enough space as well. There need to be milled an extra space, as shown in the pictures. Before milling, the locomotive needs to be covered in a plastic bag and adhesive tape around the milled space, so the dust will not get inside the locomotive. It is also a good idea to remove the motor.
Then the PCB needs to be prepared for loadspeakers - just 2 additional holes are needed to fit the top of the loadspeaker in it. After the wires are connected to loadspeakers in serial configuration, they are glued by a cyanoacrylate glue to the PCB, wires are shaped in the manner they will fit between the space left in motor and flywheels.
At the end the decoder connector need to be placed instead of the original small PCB for analogue operation, with orange wire (1) oriented down. The connector pins need to be L shaped before connecting it, so it fits behind the driver's cab. Then a short test ride and the locomotive body can be put on.
