[BVM]

Having purchased extra function only decoders for the lighting in the Bachmann Class 108 I am very disappointed by the result.

In the power car the motor block effectively kills the light that end and the light at the other end is only sufficient to light up the first compartment. In the trailer cars and middle carriages only the end compartments are lit.

To me it needs at least one extra LED in the middle of the cars.

Has anyone done this or thought about how to do it?

 

[BVM]

QUOTE (SouthernGreen @ 19 May 2008, 22:05) <{POST_SNAPBACK}>Have you considered the strip LEDs from DCC Supplies? - warm white probably best for carriage lighting - as it has solder tabs should be a piece of cake to swap for the Bachmann equipment.

No- but a helpful suggestion that I will investigate; thanks.

 

[BVM]

QUOTE (SouthernGreen @ 19 May 2008, 22:05) <{POST_SNAPBACK}>Have you considered the strip LEDs from DCC Supplies? - warm white probably best for carriage lighting - as it has solder tabs should be a piece of cake to swap for the Bachmann equipment.

One should always be suspicious when some one says "it will be a piece of cake"!!

It is all bit of a nightmare.

Bottom line is that LED strips do not work. The strips have resistors built in but Bachmann have also built in resistors. Result is that existing LED's take the current that is available and the strip doesn't light at all.

Here are a few of the things I learnt-

1. There are two brass contacts at each end of each car so you would think that there was a + and - each end. WRONG. There are three +'s and only one negative. The circuit board in the roof of each car is basically a negative strip.

2. There are a series of surface mount components on the underside of the circuit board in the floor of each car, resistors, diodes and some components I do not recognise. It is too difficult to work out what does what without a circuit diagram.

3. In the process of trying to work out what was going I managed to blow the leds in the roof of the car I was working on. I removed them and then I got the LED strip to work but because of the limited current available I needed 4 elements (or 12 leds) to get any sort of reasonable result and even that is not perfect because there is a small graduation down the strip-brighter one end than the other. You also have to remove the plastic diffuser to compensate for the thickness of the strip. Taking the leds out only works for the middle cars because in the others you need the led for the route indicator. In any case you cannot get the roof circuit board out in those cars because it has been glued in one end with the cab end details. This also means in those cars you have to solder to the board inside the car which is somewhat scary.

4. I am now an expert at putting the bodies on and off!!!

5. I think the best approach to improving things will be to add two leds in parallel with the existing ones but located at the third points along the cars and this would also require cutting a slot in the diffuser. It would also be a lot cheaper than the led strips. I may have a go at that once I have regained my composure and energy levels.

 

[BVM]

QUOTE (BVM @ 29 May 2008, 18:03) <{POST_SNAPBACK}>One should always be suspicious when some one says "it will be a piece of cake"!!

...................

5. I think the best approach to improving things will be to add two leds in parallel with the existing ones but located at the third points along the cars and this would also require cutting a slot in the diffuser. It would also be a lot cheaper than the led strips. I may have a go at that once I have regained my composure and energy levels.

I have done a bit more experimentation and have two solutions;

1. The simplest but most expensive is to remove the existing LED at the decoder end of the unit and to use three elements of the flexible LED (9 LEDS). This can be off centre since the existing LED at the other end will still work. In the cars where you can totally remove the roof circuit board it is relatively easy to just wire the strip to the terminals used by the old LED. They are very close together and it is more difficult to do that when working with the board in the car. However in that case the two brass contact springs can be used as at this end of the car there is a positive and a negative. Three elements also fit better than four and they are pretty much the same colour temperature. It also helps to replace the plastic diffuser as this does help distribute the light more evenly and it adds both rigidity and weight to the cars. However you have to nip an 1/8 inch off the tops of the compartment dividers to do that.

2. Adding two further LED's in parallel to the existing LED's does not work as the existing LED takes all the current (I did not have any bright LED's to hand so was using regular 3mm ones-it is possible that two bright ones might more evenly split the available current). The decoder I am using had a function 4 lead not connected to anything and so I used that to connect to the cathode of the two additional LED's and connected the anode side to the plus terminal at the end of the car thus using the existing resistance. This works reasonably well but the two new LEDs do dim when the existing LED is turned on. You need the diffuser to spread the light and this means cutting two holes in it for the new LED's. It then fits back without the need to trim the compartment dividers. However ordinary LED's are quite a different colour temperature to the two existing LED's so it is not a satisfactory solution but I think it would be with two of the very bright variety similar to the existing ones. It is however a lot more hassle and at the end of the day probably only £3 cheaper than using the flexible strip. A variant of this approach would be to put a tee in the blue wire off the decoder providing a separate feed but it would of course also need a resistor and it is more to tuck away inside the car.

So I am going to adopt solution one!