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Fitting a Bachmann 21-pin decoder to a Bachmann 4-CEP EMU

Please ensure you have read the Readme post before using this guide - this can be found HERE




This model requires only one decoder (21-pin) for the whole four-car unit as it is wired through for internal and headcode lighting. So only the powered car, which contains the decoder socket, is shown for this guide.


For this installation you will need


  • Several pieces of plasticard/old credit cards
  • Some strong fingernails and quite a bit of nerve


The fit of the body is very tight on this model. You will need several pieces of plasticard or old credit cards. Carefully seperate the bodyshell from the chassis and slide pieces of plastic in underneath the clips starting from the middle and working towards each end.





There are five clips along each side. Once you have six strips of plastic in place, you can attempt to remove the chassis.


There is no flexibility in the all-metal chassis and is very, very difficult to get plasticard into the endmost clips because of the cast footsteps. this is particularly true at the cab end.


instead, using your fingers, prise apart the body from the chassis at the inner end and gently pull downwards


It is not easy, but you should get around 1/4" of chassis exposed




The next bit is tricky. Eight of the ten clips are disengaged, leaving the clips at the cab-end engaged.


If you have good fingernails or a particularly strong card, run it down one side of the bodyshell to the cab, whilst exerting pressure on the chassis to seperate it from the body.

Otherwise give it a tug, though it is hit and miss as to whether the cab-end clips will break - sometimes they do, sometimes they don't, there is not a lot you can do about it, though I find adding a slight twisting motion on the chassis helps to reduce this risk. It should come away with one swift crack.


Don't worry if the cab end clips do break, there are eight others, and the body fit is tight, so structural integrity is not compromised.


Here is what you are left with, you can see the 21-pin socket and the five clips on the side of the bodyshell




Remove the black 21-pin blanking plate - ensure you lift this squarely or you risk bending the pins.


Insert the 21-pin decoder




Test chassis at this point to ensure the decoder is good (And save having to remove the body again) - the lights should come on in the cab when switched on.


Replace the body by placing it squarely on the chassis, ensuring that the chassis clears the ends of the body. press down firmly and the body should clip frmly into place.



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