Hows your soldering skills? It's doable to keep the existing motherboard and use a 21pin adapter but you've got some work to do and the only outputs the adapter can power is the headlights and the front ditchlights (depending on the adapter you have).
It's as I thought. See all those little items labelled Q1 to Q8 on the bottom on the motherboard? those are the transistors to "amplify" the logic level outputs from the Loksound decoder to make them capable of driving LEDs, lamps etc. It appears all the resistors are on the motherboard as well. This is a plus and a negative. Negative because we can't use them with the adapter and plus because we can easily bypass them.
What you will need to do is for each item in the table that has a logic level output is (ignore the transistor in the table, I was just guessing which transistor was for which output):
Unsolder the wires between the pads between the little boards (on the chassis) and the motherboard and solder on a wire from the LM to the pads on the little boards. You'll need to put a resistors inline as well. U+ will need to be connected to the blue wire on the 9 pin harness.
Table 1 : Rapido B36-7 - LokSound Auxilliary Outputs| Output | Output type | Programmed effect | Transistor (guessed) | DCC mapping |
| X1 | Power | Ditchlight Type 1 (alt phase) | | F6 - Ditchlights (Front) |
| X2 | Power | Ditchlight Type 1 | | F6 - Ditchlights (Front) |
| X3 | Logic | Dimmable Headlight | 1 | F11 - Class lights (Rear) |
| X4 | Logic | Dimmable Headlight | 2 | F19 - Numberboards |
| X5 | Logic | Dimmable Headlight | 3 | F11 - Class lights (rear) |
| X6 | Logic | Ditchlight Type 1 | 4 | F6 - Ditchlights (Rear) |
| X7 | Logic | Ditchlight Type 1 (alt phase) | 5 | F6 - Ditchlights (Rear) |
| X10 | Logic | Oscillating Headlight | 6 | F17 - Emergency light |
| X11 | Logic | Gyra light | 7 | F13 - Gyra light (Front) |
| X12 | Logic | Gyra light | 8 | F13 - Gyra light (Rear) |
or, as much as I really don't want to say you might be able to use a decoder buddy from
nixtrainz and use the adapter with that and scrap the factory motherboard all together.
You could also, if you feel macho enough just make a new "motherboard" from plain PCB or stripboard and go from there.
-Tim
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