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Discussion Starter #1
Friends,
I just bought a new MRC Power G transformer. I have used the MRC Control Master 20 in the past, but wanted a little more consitent power for a longer track extention outside. Pack runs LGB 21192 Mogul very well, sound works fine, however, the headlight flashes as it runs. Is something wrong? When I run this loco with the MRC 20, no headlights flash. Running a Bachmann Annie on the MRC Power G gets no flashing lights. There does seem to be a slight burning smell from the new transformer, but that could be from the newness of it. It does not get hot to the touch. Any ideas? Suggestions?
 

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Ted, The powerG doese have a " burning " smell to it for a while, but it will go away after some use. I have one and love it. I run MTH DCS with it. I don't know alot about LGBG loco's but maybe you should check the power pick-ups on it to see if they are dirty. Or check the track to see if it has some dirty
spots on it.
Cliff
 

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The flashing headlight belies its electrical simplicity - ie, not very effectively filtered on the DC side. Converting transformer AC output to DC with rectifiers creates a spiky DC, its frequency dependent on the arrangement of rectifiers. That's one of the reasons power supplies have those big fat capacitors in them. Incandescent lamps are very sensitive to voltage variation, so the as the DC flickers some, the lamps will flash in sync. The motor doesn't care due to something called hysteresis. The sound board has its own on board power conditioning, so it doesn't care either. The Control Master 20 is a more sophisticated (electrically) product than the Power G. The G uses raw resistance to vary the voltage, whereas the CM20 uses pulse control. I looked at both originally, and chose the TE instead with a fixed supply.

Some locomotives have on board power conditioning for their lights. If the LGB uses 14-18v incandescent bulbs, you'll see the flicker.
 

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As a troubleshooting question, how does the light flash? Is it a consistent, regular flash, or erratic flashing? Does it change with engine speed/throttle position? That is, at higher throttle positions, is the flashing less frequent? Different power supplies control with different methods. Some supplies vary the actual voltage to the track, while other supplies provide nearly full voltage, but pulse it on and off. At lower throttle settings, the pulse is narrow with a longer time between pulses. As you increase the throttle setting, the pulses get wider (or longer) and the gaps get shorter. Different people like it different ways. On some locomotives, there are electronics on board (a simple resistor/capacitor circuit) that will smooth out this effect for the lights.

Michael
 

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Discussion Starter #5
Michael,
It is pretty consistent at all speeds. It almost looks like the ditch lights on a diesel (but I am running Rio Grande narrow gauge steam). I have ran several locos and this seems to be the only one doing this at the moment. At first, I sure thought it was a power pack problem, now I'm not sure.
 

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Since LGB moguls have a voltage conversion circuit inside and create 5 to 6 volts for the lights and smoke, some power packs are incompatible with these engines.

If the engine has sound, some power packs can destroy the sound cards due to output voltages being higher than what the electronics can handle.
 

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I would guess that it is a compatibility issue between that locomotive and that particular power supply. One test, if possible, would be to get another similar model loco and see if it does the same. If available, I'd look at the power supply outputs with an oscilloscope and compare them, looking for ripple, pulses, etc. Contact with the manufacturer tech support might give some answers as well.

Good Luck.
 
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