Bachmann OO Class 90 with Zimo MS sound

Kit: MS440C

Revisiting the excellent Class 90 to see what MS kit can be fitted, and rememering that it needs to work with the pantograph too.

Upgrading to DCC sound is no problem in itself - the roof panel is removed and an MS440C 21pin sound decoder is put in, in place of the blanking plate.

We check that the pantagraph operates correctly with the MS440C - a little tweak of CVs here.

To do more with this model we need to do a bit more work though... stay-alive and improved speaker are very useful - especially the speaker, as the factory unit it not great.

The speaker PCB is unscrewed and the speaker component take out, then we grind off the whole of the speaker enclosure in the roof to make maximum space for something better.

The space is not quite big enough for a dual SugarCube (24x15mm), so instead we opt for our 3D Custom speaker that was designed for the Hornby Class 800! Same speakers, just a couple of mm less in length (22x15mm).

Even that, at 22mm, is marginally too much to fit through the hole in the model's PCB, so we very carefully file the PCB edge inside the hold to widen it - doesn't need much - just untli the speaker slides through.

Once in position, we run a tiny amount of SuperGlue around the edge of the speaker, and a little BlackTack to secure it all - perfect fit, and a massive improvement over the original speaker.

With the body back on, you can see how tight the speaker is the room, so every mm created was worthwhile!

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