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Bachmann HO Shay

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  • Member since
    March 2008
  • 29 posts
Posted by Tom M. on Friday, February 15, 2013 7:55 AM

My fix is not a novice project.  In conjunction with installing a Tsunami DCC sound decoder, I replace the factory lighting by installing a golden white surface mount LED (SMD 0602) into each light housing.  A 1 K ohm resistor is wired on the negative leg of each LED circuit to reduce voltage to the LED.

With many Bachmann locos, it is not just the resistor value they use that causes a dim light output.  It is the placement of the LED and poorly designed light tubes used to transmit the light from its position to the light fixture.  There is a tremendous amount of loss in this arrangement.  Placing the LED within the fixture eliminates the loss issue.

Tom

  • Member since
    October 2006
  • From: Western, MA
  • 8,571 posts
Posted by richg1998 on Thursday, February 14, 2013 9:45 PM

A 20 ma LED will have 9 ma flowing through it with a 1 k resistor which is assuming about 12 VDC from the decoder. A 2.5 k resistor will limit the current much more. A good reason for dim LED. No idea on how much a light pipe will decrease the light intensity as I did not do any experimenting.

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

  • Member since
    October 2006
  • From: Western, MA
  • 8,571 posts
Posted by richg1998 on Thursday, February 14, 2013 9:39 PM

mdy

can anyone help me, I want to know if any one was able to get the headlight and backup leds to glow brighter? what did you do, I have talked with Bachmann service and they said what you got is you get , dose any one else have this problem? any help or sugjestion would be thank full. AM using NEC power on a 4x8 layout and am a navice 

mdy

can anyone help me, I want to know if any one was able to get the headlight and backup leds to glow brighter? what did you do, I have talked with Bachmann service and they said what you got is you get , does any one else have this problem? any help or suggestion would be thank full. AM using NEC power on a 4x8 layout and am a novice

Bachmann is known to use a much higher resistance than 1 k for LED resistors.

I have measured as much as 2.5 k from what I recall in my 4-4-0 and 4-6-0'

Some other Bachmann locos have the same issue. I know the 2-8-0 does.

Get your meter out and find out which resistors are used for front and rear. Find out what the resistance is and either replace the resistor or calculate what you need to put in parallel with the present resistors to get the total resistance down to 1 k. The resistos are eeasy to find. They have an R. Cut the caps. They have a C. The two green things that look like resistors are inductors.

Some users rip out the PC board and hard wire for this reason, adding a 1 k resistor.

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

mdy
  • Member since
    February 2013
  • 223 posts
Bachmann HO Shay
Posted by mdy on Thursday, February 14, 2013 6:51 PM

can anyone help me, I want to know if any one was able to get the headlight and backup leds to glow brighter? what did you do, I have talked with Bachmann service and they said what you got is you get , dose any one else have this problem? any help or sugjestion would be thank full. AM using NEC power on a 4x8 layout and am a navice 

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