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Dapol OO Large Prairie

Dapol OO Large Prairie

Example 1: Simple, using Dapol's slide-out PCB

Kit: MX658N18 (or MS580N18); StickyGasket15x11mm speaker

Designed to make DCC Sound installation very simple, Dapol have provided a Next18 pull-out PCB in the boiler - simply pop off the boiler door, unplug the board and add a decoder and speaker.

The Zimo MX658N18 is a perfect fit, and Dapol provide a speaker enclosure in the extras pack for a 15x11mm Sticky Gasket speaker. This enclosure then clips onto the pull-out PCB making contact with pads - no soldering required.

Very neat...

While this makes it very simple to convert to DCC sound, we found the performance from the speaker in such a small enclosure not brilliant - the speaker seal is a bit hit-and-miss. We also found that the loco's pickups were somewhat poor leading to common stalling. There is no way to add a stay-alive to the MX658N18, so will have to wait for the MS580 to do that. We'll attempt a rework using a better speaker in a future example, so watch the space below!

Example 2: MS580 with Tantalums stay-alive

Kit: MS580N18; 15x11mm Sticky Gasket speaker; LifeLink + 4x 470uF Flat Tantalums for stay-alive

Similar approach, but this time with the new MS580N18 sound decoder, which can have some stay-alive attached. We want to add 3 or 4 of the 470uF Flat Tantalums, so this has to be connected to the decoder's normal common positive and ground solder pads via a LifeLink.

The 12V common positive and ground pads are next to each other, close to the plug end. Blue is common, and a grey wire is added for ground.

These wires go to the LifeLink input, and from there we join to a parallel array of Tantalums.

This is a different variation, using 3 Tantalums, and the LifeLink is placed on the same side as the capacitors. Whichever combination you go with, just ensure that it is as neat as possbile so it slides into the boiler still.

This seems to work OK, though the effect from the stay-alive is not as great as we'd hoped. We also don't like this speaker arrangement - the baffle box just doesn't give a good seal and audio performance is limited.

Example 3: hard-wire - bigger speaker and big stay-alive

Kit: MX648 (or MS480); SugarCurve9; LifeLink + 17000uF SuperCap for stay-alive; improved firebox LED

Ok, so this model was designed with its' sliding PCB to make sound fitting easy, which it does, but unfortunately the results are a little underwhelming in terms of stalling and audio output. Therefore we next look at a more extreme approach, gutting out the engine in order to hard-wire the best possbile kit...

Body, frame, and chassis separated, we remove all of the electronics.

Here we have an MX648 hard-wired, or we could have used the new MS480 instead. The SugarCurve speaker sits on top of the decoder, which should just slide into the boiler once the body is refitted later.

Not shown here, but we have also replaced the factory firebox LED with our own, and positioned it more in line with the firebox opening - this makes it much more visible than before, and a good improvement too.

We route wires through to the bunker for the stay-alive, hollowing it out enough for a LifeLink and SuperCap17000uF. A little fettling of the plastic is required, but this isn't too difficult to get neatly in... and boy, does this make an amazing difference to running reliability!

Another example shown here, same kit, and weathered up too...


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.

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