Decoder, PCB, Capacitor

I’ve been doing some more work on my red miniature railway loco. When I DCC’d it initially I used a large stay alive chip that was just visible between the side tanks.

I wanted the chip and stay alive to be invisible so I asked Kevin at Coastal DCC if he could recommend a smaller solution. He recommended a decoder (Zimo MX617F), and a stay alive kit (Zimo SACC16) containing a printed circuit board and a capacitor. I told him I was a DCC novice and he reassured me that everything came with instructions and it was easy to do.

When the components arrived I read the instructions carefully and, after several cups of tea, finally I got my head round it. As Kevin has said, it didn’t look that difficult. I heated up the soldering iron and got started.

First job, solder the decoder to the chassis and motor. This was pretty straight forward. The blue wire is the ‘Common’ which we need later.

Next the PCB and the capacitor. The PCB controls the recharging / discharge of the energy stored in the capacitor.

The instructions suggested that the PCB could be cut to make it smaller if needed, so taking my courage and a Stanley knife in my hands I cut the PCB.

Soldering the capacitor to the PCB was easy, but you need to be sure you solder the negative terminal on the capacitor to the negative terminal on the PCB.

Strangely, the negative terminal is marked on the capacitor (but not the positive) and the positive terminal is marker on the PCB (but not the negative). Dr Spock would say this is illogical 🙂

The PCB and capacitor must be connected to the decoder. The blue common (+ve) wire is soldered to a positive connection on the PCB. A negative connection is needed too, but there’s no built in wire for this on the decoder. I soldered a purple wire to the ‘Ground’ on the decoder and connected it to the PCB.

Here’s the final result.

Will it work?

A quick test run revealed that it works fine. Phew!

The stay alive definitely doesn’t last as long as the TCS KAM4 stay alive, but it seems to make a difference to the running and that’s nice.

I need to cover all the parts in ‘heat shrink’ and fix them in place with double sided tape before I use the loco. However, I don’t have any heat shrink, so that’s a job for another day…..

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