Let's fit a Zimo MX645 sound decoder to this Bachmann OO Standard 4MT Tank... take the body off the chassis by removing the 4
retaining screws... 1 at each end plus 1 each side half way along the chassis:
This model came factory-fitted with an 8pin Bachmann decoder, which we'll unplug.
In order to fit in a sugar-cube speaker and the MX645 decoder, we need to remove the 8pin DCC socket and mounting points:
The speaker then sits flush where there socket was. In this example I've used a 12mm high Zimo sugar-cube. The MX645 goes into
the same place that the original Bachmann decoder was, with any unused wires trimmed a little and stuck neatly out of the way.
Zimo provide purple wires for the speaker connection. I've also left the blue and green wires available, as I shall add a
firebox glow light to this model (not detailed here):
All back together, and tested - a very quick and simple installation!
All disassembled and with the MX649 hard-wired and SugarCube9 in place in the boiler.
Perhaps the toughest part of this install is cracking off the bunker... it was really wedged on with this example and needed a
lot of persuasion to come off, but once done, we have easy access to the cab to add crew, firebox glow, and route a pair of
wires through to the bunker for our stay-alive.
We add longer wires for the stay-aive / SPEIKOMP kit, which are blue and grey from the decoder (blue is the existing common
positive blue wire and grey is a new wire soldered to the GND pad of the decoder (not to be confused with the grey motor wire!)
We also have the blue (via a resistor for the firebox glow LED and orange for the firebox glow negative (connected to the
decoder's green AUX3/FA1 output).
Just the stay-alive blue and grey wires come through the cab, filing a notch in the bunker wall so they can come right inside
the bunker when reattached.
The SPEIKOMP kit is assembled, and a 1000uF electrolytic capacitor is hooked up.These fit easily inside the bunker space.
Bunker screwed back in place, and chassis screwed down, final touch is to just add some lump coal.
Here's a similar one, in green this time, but using IceCube18X13X10-1W speaker intead. MX645 hard-wired, firebox glow, a pair
of 1000uF electrolytic capacitors for stay-alive in the bunker...