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Discussion Starter · #1 ·
The lights in my USAt GP7 require 18v before they suddenly switch on. I can then reduce the voltage, the lights gadually going dimmer until they finally go out just below 4v.

Has anyone got any idea why this would happen?
I have to wind up to almost full speed to get the lights on, and then slow down to my cruising speed... /DesktopModules/NTForums/themes/mls/emoticons/sad.gif
 

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Super Modulator
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21,410 Posts
If you have not modified the loco, and you are running on DC, you have a faulty main board, there is an on-board regulator, if you measure the voltage at the bulbs, you will find about 5 to 5.5 volts.

The regulator should start passing voltage at a much lower track voltage.

All the GP7/9's I have found use two wires to each end, and the headlights (GOW), number boards (small screw in bulbs) and the classification lights (red/green dual leds with 3 wires).

I think you will need a new main board.

Regards, Greg
 

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Discussion Starter · #3 ·
Thanks Greg!

At the bulbs, the voltage is 3v, On my USAt F3 which appears to have the same bulbs, the voltage is 5v.
Could it be the voltage regulater in the geep that's gone? This could be an easier fix if so?
 

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Old Senior Member
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1,456 Posts
Yes like most has said.. Get it the reg./ board fixed or replaced. I had one go bad in my SD40-2 and it blow all of the lamps out.. Had to replace them and the regulater. Its not a easy job to replace all of them..

While I had it apart I change out the head lamp to LED's and added a 10 ohm risistor. 1/4 watt. between them
Now head light come on at 6 volts to the tracks. But my Aristo Power supply only put out 18.5 volts. to the TM's. here in the boonies.
 
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