Troubleshooting Bachmann N NW2 DCC board

[Joetrain59]

Hi,
 I'm looking for the original DCC board for the Bachmann, N NW2, including the rear light board.
 Did not see it on Bmann parts page on website.
 Any help is appreciated,
 Joe D

[Joetrain59]

I called Bmann today, looking to get these parts. Lady on phone checked with manager. No parts,
 as it was not a very popular item, and is discontinued!
 ?????
 Joe D

[Joetrain59]

Sorry to keep beating a dead horse, but does someone make a decoder for these loco's?
 Or, how do I "un DCC" it? Removing the Bmann board, for DC only use.
 Thanks,
 Joe D

[peteski]

Sorry to keep beating a dead horse, but does someone make a decoder for these loco's?
 Or, how do I "un DCC" it? Removing the Bmann board, for DC only use.
 Thanks,
 Joe D

What is the current status of that model?  Is it complete except for the missing circuit boards?

Looking at the exploded diagram ( https://www.bachmanntrains.com/home-usa/dwg/dwgs/N_Scale_NW-2_SWITCHER.pdf the decoder board sits on top of the motor, then there are separate front and rear LED boards. I assume that the motor and trucks have wires attached to them (which were probably soldered to the decoder board) The headlight boards were probably wired to the decoder too. 

If you want to run it on DC, just run some wires to connect the right truck pickup wires to the positive (red?) motor lead, and the left truck pickup wires to the negative (blue?) motor lead.  That is all that's needed. Very basic and simple hookup. If you want to have working headlights, there will be more work needed.

[Joetrain59]

Pete, something went wrong with the main board that is on loco. I had made a note on loco case, "no DCC".
 The rear LED does not light. I have traced the trouble to the board. I would like to have the the headlights
 of course. Bmann suggested I go to the "Ask the Bmann" forum. "Maybe someone has a board there to sell you".
 Whole different crowd there. ;(
 Joe D

[peteski]

I misunderstood you. You want to get the loco running back with a decoder.  Bachmann uses crappy decoders. Why not just replace it with another brand wired-in decoder?  You can probably get a Digitrax DZ125 for about $20.

Yes, I sometimes visit the Bachmann forum, and I know what you mean.

I'm also curious if the original decoder is totally dead, or works ok except for the rear LED?

[Joetrain59]

Pete, I'll have to hook up the NCE DCC throttle, but I did write that note on jewel case, "no dcc".
 Joe D

[Joetrain59]

I did run it on DCC. Front headlight dims in reverse. Does that in DC too. No rear light.
 Could it be a matter of settings to program? When new, the rear light did work,
 but I did change out the SMD LED's for brighter ones. IIRC, rear light worked for a while.
 Joe D

[peteski]

I did run it on DCC. Front headlight dims in reverse. Does that in DC too. No rear light.
 Could it be a matter of settings to program? When new, the rear light did work,
 but I did change out the SMD LED's for brighter ones. IIRC, rear light worked for a while.
 Joe D

Sure sounds to me like a problem with the rear LED.  I dont' think Bachmann decoder has a capability to disable the rear headligth - those are *REALLY* basic decoders!
So it is likely an electrical problem.

Since the rear headlight is a separate board (connected to the decoder by 2 wires), I would unsolder it from the decoder (making a note of how the wires are connected, since polarity matters), and test the wire/board/LED assembly.  If the current limiting resistor is on the LED board, then just connect the wires to a 9V battery and the LED should light up (without blowing up).    If only the LED is on that board, you will need to add a 1K resistor in series with one of the wires before connecting the 9V battery.

If the LED doesn't light up then you need to figure out what is bad and fix it.  If the LED lights up, then the problem is on the decoder (could be a blown transistor on the reverse headlight function output).  Even if that is the problem, those decoders are crude - the components are large (as far as SMD components go - it can likely be replaced).  I suppose other part of the decoder could be the problem, but that is unlikely.

[MK]

I dont' think Bachmann decoder has a capability to disable the rear headligth - those are *REALLY* basic decoders!

That is the case with the two recent S4's that I got.  Rear light is always on though if you are going forward it dims (barely!).

[Joetrain59]

I did use a LED tester right to where the rear led board wires connect to the DCC board, but not disconnected from DCC board. I will try this tonight. Led tester has a resistor in it.
 ( I did look at the TCS site for a decoder, but none for Bmann locos.)
  Thanks,
 Joe D

MODERATOR, maybe this post should move somewhere else?

[Joetrain59]

More on this later today. But the LED itself is good.
 Joe D

[Joetrain59]

Everything is working fine now. Most likely my bad, again.
 I did the LED swap on this loco several years ago, before I was more
 knowledgeable. I had been intimidated when soldering a sub 2x3mm chip
 to a board, and used #38 magnet wire. Even though rear led did light when tested,
 this time one of those fine wires had broken off the pc board. With the confidence I now have,
 I soldered chip directly onto pc board, and all is good. I realized an issue that made me timid,
 and found a way to beat it.
 Thanks,
 Joe D

PS, these are really smooth, and quiet running locos, like Spookshow said. I have maybe 6 of them?

[peteski]

Nice to see you gaining confidence in dealing with electronic circuits.  Good fix!  And you didn't even need a new decoder.

[Joetrain59]

I made a tool better, to help me. Took a small, smooth jaw gator clip, and narrowed the
 jaws, to better fit the micro led. That held it in place, so my unsteady hands could solder it.
 Joe D