Hardwiring a DCC chip into a Mehano GG1?

[GraemeWatson]

Hi, ended up buying my first HO loco, a Mehano Pennsylvania GG1, for the simple reason I liked the look of it.

I'm fairly competant at hardwiring chips in UK OO locos, but the inside of this features front and rear motors, and bulb lamp headlights.

Anyone hard wired one for DCC operation, who could perhaps post a photo or tips?

I've trawled around google to no avail.

Many Thanks

[Marty Mc]

Hi

 

Firstly test on DC to see what the current draw is. Have the loco pull 500-750g of weight as this will be a better indication for full load. I do not recommend a stall test but a slip test.

 

Depending on max current, select your preferred decoder, I would recommend Zimo, DCC Concepts or TCS decoders. Its up to you but if your loco pulls lets say 800mA under full load you are fairly safe with a 1A decoder as you have a 20% safety factor built in.

 

If you have no real issues hard wiring (I always hard wire) I would suggest removing the PCB board completely if it has one.

 

Test each motor for and make sure you have the correct motor terminals identified for direction of travel. I would suggest switching off the Bemf and then wiring normally except you will be linking 2 motors to the orange and grey.

 

Give it a test and you can try it with the Bemf switched on but from experience it will not run as good. As I said best leaving it off but for the purpose of seeing the effects give it a try.

 

Next lets assume you have purchased a 4 function decoder you will have 4 functions to allocate to the lights. Depending on how bright or dim you want the lights you need to put some resistance in series with the bulbs. Sort of like doing LEDs but they are not polarity dependant. Start out with 50 ohms and go up or down from there depending on what light level you want. Ohm's law will give you a guide but cannot help with the actual light level.

 

I always like to put my resistor on the negative side of the decoder eg white, yellow green etc. If you stick with the bulbs try to drop the voltage to around 8-9 volts as this will greatly extend the life of the bulbs...........unless they are 6v or 3v then drop 1.5 and 1V to extend life.

 

I would suggest changing from bulbs to LEDs if your going to do all that but again your choice. Start with 1k of resistance and go up from there.

 

Hope that helps and best of luck.

 

Martin

[GraemeWatson]

Thanks Martin, that's great advice.

Should be no problem, but having had you talk it through, you've given some great tips.

 

I was definitely going to change over to LEDs, so hopefully won't have much trouble!

 

Thanks again!

 

Graeme

[GraemeWatson]

No problem Dutch Master. She's on my bench to tackle after some regular UK models (as well as the usual ongoing Christmas related activities). I've briefly tested it on DC and I really like it.

I'm going to swap the nose bulbs for "warm" LEDs, I reckon.

Even though googling seems to suggest that mehano models are a bit like "Lima" I must say, I'm pretty impressed with the durability, and the exquisite pantographs.