Using MX660 Drop-in Sound Decoder - no milling needed

Kit: MX660 Drop-In Sound Decoder + SugarCurve6 + SACC16 + 2x 330uF Flat Tantalums

Here is our donor model...

Body off and factory PCB out...

Try out the speaker and decoder for position, so we know where they will so...

Place thin double-sided tape across the length of the chassis where the decoder will go, and protect the underside of the MX660 with Kapton tape. The motor, pickups and speaker can all be wired in and tested at this point. The speaker sits on some more double-sided tape and is covered in Kapton to protect it from short-circuit on the chassis.

To re-add the model's lighting modules, it is best to replace the wires completely - fresh wires are always nicer to work with, you can have them a better length, and you can use more sensible colours (DCC standards are a good idea). We've used BLUE for common positive, WHITE for white LEDs and YELLOW for red LEDs.

Not sure why they designed the modules to have 3 separate positive connections, but they did, so we simplify it by looping 2 pairs of the positives back to each other, so only 1 blue wire actually leaves the module.

The lighting board is protected with a little piece of electrical tape on the back - must be fairly narrow so that the board still slots into the grooves provided in the chassis.

Slide the lights back into place, tidy the wiring, and secure the speaker and decoder down with a couple of thin strips of electrical tape. You can now test that everything works - motor, sound and lights. We've wired our example up to have independent red and white light control, as the MX660 has 6 function outputs altogether, so we'll make use of them. YouChoos can supply the decoder pre-configured with function keys to match - just ask when you order!

There is plenty of room left inside, so we add stay-alive, in the form of the SACC16 PCB, and a couple of thin/tall 330uF Tantalums. The Tantalums are placed in a convenient gap near the speaker, and the SACC16 is thin enough to simply sit on top of the MX660 (wrapped in Kapton of course!).

All very tidy, time for another test. The 660uf-worth of stay-alive make all the difference to reliable running.

Just for good measure, we also include independent cab lights - remember the MX660 has 6 function outputs, so we might as well use them!

All done...

Please note that these guides are provided as useful resources for you, as-is. YouChoos cannot be held responsible for errors in the information, or for any damage caused to your models or equipment if you choose to follow any of the steps detailed here.