1.5v Light Bulb with TMCC

You need to know the current to the bulb, but I suspect a 1K resistor will be too high a resistance.  The TMCC light outputs put out an effective 9V, so you'd only get 7ma of current at 1.5 volts.

I suspect the bulb is at least a 50-60ma bulb if not more.  If you can, use a 1.5V battery to light it and measure the current with a meter to see what the bulb requires.  It will be easy to calculate the proper value resistor at that point.

Gunrunnerjohn

Thank you for your reply, unfortunately I don't know enough about doing such a test.

Perhaps someone here has a Weaver with those bulbs and could do the test.  Why do you feel it would be difficult to replace the bulb, a replacement would be the ideal solution.

The head light was a 6 volt bulb and I found out the hard way when I first tested the engine. The bulb burned out immediately and was very difficult to change out with a LED and I had a lot more room to work. This is a brass engine and all the pieces are soldered on. 

How did you determine the backup light was 1.5V?  Was this a QSI board and wired to the board for the backup function?  FWIW, I've put LED's in a lot of different brass locomotives.  Sometimes the easiest way is to remove the headlight lens.

Yes, it is a QSI board and the backup light was wired to the board. Also there was a wiring schematic included with the instructions. The schematic showed the voltage for each of the bulbs. 

Thank you for your help and suggestions. I'm thinking I will try a LED.

If you can get an LED in there, that's probably best.  If not, finding out what current the bulb draws would help us help you.

So you can't change the bulb to a 12-14V GOW? G