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Dapol OO Mogul

Dapol's 2020 OO Mogul model is something of a minor revolution in internal design, with a number of innovative features to make DCC Sound fitting easier. A pull-out PCB slots into the boiler, accessed by simply pinging off the press-fit boiler door.

This pull-out PCB has a Next18 socket, ready to take a Zimo MX658N18 sound decoder on the top, and a 15x11mm speaker component underneath, housed in a chamber (supplied with the model). The chamber simply clips into the PCB allowing the speaker's spring-clip terminals to touch contact points on the PCB, so no soldering required.

In addition, the model has a pair of LEDs for firebox glow effect (yellow and orange).

Connection to the tender is via a new style solid contact bar, which is spring-loaded both sides, giving 4 electrical paths... 2 for tender pickups and 2 if you want to place a larger speaker in the tender instead of in the boiler.

Not only is it very welcome to see these features, but the model is also very well put together, and motion is smooth and quiet - first impressions are very impressive.

*** WARNING *** However, before we begin, it would be a good idea to check that Dapol have got the speaker and pickup wires in the tender the correct way around, as we've found quite a few models where they've been incorrectly wired the wrong way, which blows a sound decoder as soon as you put power onto it! An easy way to check is on DC - lift the loco off the track, leaving just the tender, and it should still turn the motor, then try with tender lifted and loco down - both should work OK. You can also try a line-test between the flying speaker wires in the tender and the loco wheels, which should not show any connectivity.

Example 1: Speaker in the loco

Kit: MX658N18; 15x11mm StickyGasket Speaker

We'll start with the easy approach, putting the intended 15x11mm speaker in the supplied chamber in the boiler with the decoder... you can see the supplied chamber here, as it is desinged to clip onto the underside of the PCB.

We didn't need to take the body off the chassis, but were just nosey to find out how much extra space there might be, and to see the plug-in socket.

Here is the 15x11mm StickyGasket speaker component ready to go into the chamber.

The MX658N18 will just plug straight into the PCB on the top side.

Backing peeded off the speaker and inserted into the chamber - no need for any glue - it fits perfectly.

Slotted back together and testing... again, remember you don't need to remove the body - we were just being nosey!

Here is the assembly in position within the boiler - very neat design.

Perhaps the most disappointing aspect of the model is that you can barely see the firebox lights through the cab aperture. Sad, because the LEDs themselves are actually quite bright. Simple solution though - a bit of foil from a KitKat wrapper to reflect it out, makes all the difference!

Example 2: Bigger speaker in the tender

Kit: MX658N18; Zimo Dumbo LS26X20X08-1W

Ok, so that was easy, but the volume from the little 15x11mm speaker is only 'adequate'... if you are wanting more volume, and some grunt/depth to the chuff sounds, then you need to ditch the speaker from the boiler and put something a bit meatier in the tender...

15x11mm speaker comes out (you cannot use 2x 8ohm speakers with the Zimo MX658N18, which needs 1W and 8ohms... if you have both speakers, then it will end up 2W and 4ohm, which is not compatible, and you'll eventually damage the decoder.

We've gone with a Zimo Dumbo LS26X20X08-1W here, which fits with room to spare, but sounds really good...

Some double-sided tape to hold it in place underneath and toward the rear...

Solder the speaker to the model's pre-routed wires, which is a piece of cake, and off we go... hear the difference! The sound is substantially better than the boiler speaker.

Here is the completed model, back together, looking very handsome... well done Dapol - good job indeed!

Example 3: Stay-Alive

Kit: MX649; Rail Exclusives BigBoomer 40X20X07-1W; LifeLink with 4x 470uF Flat Tantalums

Sadly, the neat Dapol PCB with the Next18 socket does not provide a break-out pad for Ground, so it is not possible to add stay-alive and retain that board. The solution is therefore to remove the Dapol PCB and hard-wire a decoder into place. This is in fact quite simple in principle.

Losing the Dapol plug-in board will free up enough length for an MX649 and stay-alive kit. 3x 470uF Flat Tantalums would be easier, but we can just about squeeze the 4th one in... so why not!

Here the LifeLink PCB is connected to the 4 Tantalums. We used a couple of legs off capacitors/resistors to do this.

The MX649 sits on top of the stay-alive (wrapped in Kapton), with the LifeLink connected to the decoder's common positive and Ground pads.

Slides neatly into the boiler, and provides a very worthwhile stay-alive.

As an extra enhancement in this model, we decided to remove the factory LEDs for firebox and put a single large orange SMD closer to the apeture, which is so much more effective than the original light.

With the tiniest bit of filling on the speaker, we can go for the larger BigBoomer speaker (40x20x7mm), which completely fills the space in the tender - just need to be careful not to pinch the wires.

Example 4: Crazy Stay-Alive

Kit: MX649; RE BigBoomer speaker; LifeLink + 17000uF SuperCap

Ok, so the Tantalums are pretty decent as a stay-alive, but we felt like a challenge - see if a SuperCap can fit the boiler! Well, it can, but it won't be something that many people will want to do, as it requires some removal of plastic inside the boiler, including the sliders down each side where the original PCB slid in and out of. Runs amazingly though!


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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