7mm Heljan Class 47 DCC lighting

[pricei]

I've just started to convert a Heljan O-gauge Class 47 to DCC and wondered if somebody could advise me on the lighting. My loco is one of the first edition Class 47s (it must be 10+ years old) and, judging by the number of resistors on the Heljan analogue circuit board (which I'm discarding) together with the absence of any next to the lights themselves, I'm guessing I'll need to add resistors to use the lighting with a Zimo MX699KS decoder. Can anybody who's done the conversion to DCC confirm that is the case? I've included photos of the lights and circuit board below.

Assuming it is, what rating resistors should I look to use? It looks like Heljan fitted 110 and 220 ohm resistors for the red and white lights but I'm not an electronics wizzo so I may have read the colour bands completely wrong. Again, any advice on the correct resistors to fit would be appreciated.
Thanks, Ian

 

[TheSnapper]

Hi Ian
Discard the Heljan board and connect all the positive leads to a LaisDCC LED resistor board, (part 860027) with a common wire to +5v on the decoder.
The negatives for each light then go to the chosen FO connections on the decoder.
LaisDCC boards are available from a number of places such as Digitrains, Roads&
Rails etc
Model Railway Trains Spare Parts Range from LaisDcc | Dcc Decoders and Spare Parts

HTH
Tim

 

[pricei]

Thanks, Tim. I've not come across those boards before but they look to offer a very simple and elegant solution. I've ordered a couple.
Ian

 

[richard carr]

Ian

You can actually modify the Heljan board so that you can reuse it, it does help if you want to retain the roof fans.
However having seen Tim's advice above I would be buying one of those and forgetting about the roof fans, they probably make too much noise anyway.
Have you checked the running on DC as these locos were prone to split gears, mine has had this problem, spares are available from gaugemaster part number 19854780.

Richard

 

[Dog Star]

Spike has been using the LAIS resistor board with his 7mm coach lighting so as to simplify (a) the wiring and (b) demands on real estate (in GWR Victorian coaches).

The item does just what we want / need for our lighting work.

regards, Graham

 

[Ressaldar]

Ian

You can actually modify the Heljan board so that you can reuse it, it does help if you want to retain the roof fans.
However having seen Tim's advice above I would be buying one of those and forgetting about the roof fans, they probably make too much noise anyway.
Have you checked the running on DC as these locos were prone to split gears, mine has had this problem, spares are available from gaugemaster part number 19854780.

Richard

Hi Richard,

for the first time, I have wired in a roof fan - on the Class 31/4. You have to use both of the mini PCBs that Heljan use on the fan, one has a potentiometer on board and adjust it to personal choice as to how fast (noisy) you want it to run and then wire it blue to the Lais board and other wire to FA3, press F11 and away you go.

regards

Mike

 

[TheSnapper]

Nowadays, I desolder the Heljan lead from the fan control board and replace it with my own miniature plug & socket connection.
This is then wired to the selected decoder output (FO for Zimo, AUX for ESU) and to the "full fat"+ve.
The fan speed is then adjusted using the pot on the Heljan fan control board.
I find this enables quieter & slower running
This shows a Loksound 5XL, but same with a Zimo:

Cheers

Tim

 

[simond]

An alternative to the LAIS board,

https://uk.rs-online.com/web/p/resistor-networks-resistor-arrays/5224065

8 x 1k resistors in a single package. Probably only makes sense if you want a few as they appear to be in packs of 25.

 

[richard carr]

I like those Simon, nice and cheap !


Richard

 

[simond]

I’ve used them on a couple of things, for led headlights, etc, on road vehicles, which I strategically park on suitably connected manhole covers and grids. Not used them on a loco, but I’m sure they'd be fine.

 

[pricei]

Have you checked the running on DC as these locos were prone to split gears, mine has had this problem, spares are available from gaugemaster part number 19854780.

Hi Richard,
I did test the loco on DC when I took it out of storage last year and, yes, the gears had split! When I bought the replacement brass gears for my class 33 I bought a set for a 47 at the same time and these are now installed and working. I do have a second 47 to convert, though, so I'll certainly be buying the Heljan spares you've suggested for that model - a considerably cheaper repair. I've never bothered with the roof fans on Heljan diesels so I'm going to try the LaisDCC resistor board for the lights.
Thanks, Ian