Decoder identification or help wiring to correct point on Decoder

[Deem]

Hello

This is my first post here and thanks in advance for all or any help anyone give me.

I have this decoder from Bachamnn Junior Stuart, which came to me in parts and I am trying to find out what Decoder is this and which colour wire goes on which point on decoder.

[Chrissaf]

Realistically the only way to identify the brand / type / possible model of the decoder is to read the value of CV7 and compare that value to the decoder brand value listing in the published NMRA DCC Standard [s9.2.2.2 Appendix A refers]. Link to the NMRA Standard is in the "Useful Links" sticky.

Looking at the solder pads, only four have ever been used and there are no similar solder pads on the other side of the decoder PCB. This infers to me that this is four wire motor control only decoder with no additional functions. If the NMRA standard has been followed [no guarantee that it has] then the red and black wires will be the DCC track input on the decoder. This means that if you have a controller capable of reading CVs (not all controllers can) then you could try connecting the red and black wires to the "programming" terminals on the controller (if present) then try reading CV7. If it is a motor control only decoder, then the other two solder pads with solder blobs on them and missing wires are likely to be the motor orange and grey wire termination locations, but that is just a guess.

Decoders rarely give an identifiable marking on the PCBs themselves. Personally in my opinion, given how cheap decoders can be, I would bin this one as scrap. I would only try reading the decoder as an experience learning exercise.

[96RAF]

The decoder is indeed from the Stuart loco, from the Bachmann EZ Command train set, so it is presumed the decoder is a EZ command series item 2 or 3 function.

See this old post reviewing the set.

https://www.modelrailforum.com/threads/bachmann-ez-command-review.54111/

This is likely the user manual for it but although it shows the standard colours at the plug end it doesn’t illustrate the decoder.

Your best bet is to connect the track wires and motor wires and try to read CVs 7 and 8 and see if the values match those in this manual. The motor is marked M+ and M- and the track T+ and T-.

https://www.bachmanntrains.com/home-usa/ez_content/1_Amp_Decoder_Instr.pdf

Note the mantra - red and black to the track, orange and grey the other way (to motor). Your two wires look to be incorrectly connected per convention.

[Deem]

@96RAF

You have save lots of time of mine and I am very grateful for your help.

Now I know what decoder and where to connect the wire, my next question is,

There are 2 items (instead of one Decoder we normally see in locomotive) if I want install this decoder to Lima Class 156 DC locomotive how do I wire up to check if decoder is working?

Should I just use the Decoder part and install in Lima Class 156 Which have 3 Pole Ringfield motor without secondary PCB board. How would I wire the decoder?

[Deem]

@Chrissaf

Thanks for your input and I value your opinion, I am just trying to familiarise myself to basics of DCC or Decoder or Decoders.

Instead of learn or make mistake on new Decoder I am trying to explore this to make sure if I can understand or can make this work or this faulty anyway.

Thanks for your help again.

[96RAF]

Referring to that train set review we can see the secondary PCB is an old style RF suppression item, modern ones are tiny surface mount components. You do not need that if you use this decoder in Stuart or any other locos.

To be clear the only wires you need to solder are the two marked M which go to the motor and the two marked T which go to the pickups. I repeat my caution that they have used yellow wires for the track power in and red and black for the motor which does not accord with NMRA colour coding. I hope your soldering skills are first class as you will need them rewiring that decoder, remembering to take anti-static precautions.

Another caution is ring-field motors need special consideration as usually the left hand motor brush is live to the chassis and this path has to be isolated. Check Brian Lambert website for details of the various types of these motors and how to fettle them for DCC.

Edit - I find a decoder test rig such as the ESU one are invaluable when playing around with decoders, as it removes the loco from the equation and allows setting up a decoder in a safe environment.

[Chrissaf]

If the EZ decoder is indeed not wired to the NMRA standard and the red and black wires are motor connections and not track, then do not connect the red and black wires to track voltages as you will instantly blow the decoder, that is if it isn't blown already.

The Brian Lambert decoder fitting info Rob has mentioned is linked to in the "Useful Links" sticky thread [top of General Discussion forum].

[Deem]

@96RAF

@Chrissaf

Thanks again for your support, I was aware of wrong colour wire on Decoder and I try to install the decoder taking that into account.

I cleaned the Decoder points first so each wire only soldered on, one point individually.

I connecting the wire according to decoder points instead of colouring of the wires to make sure I am connecting each wire to it's right place.

When I try to use Loco with Bachmann Dynamis, nothing happened to loco, as in moving forward or backward.

I try to reprogrammed the Loco ID to new one which according to controller is completed and it show on display, loco with correct allocated number shown but no movement.

I can't get the option of read the decoder like I get with Hornby Class 08 fitted with 4 Pin Hornby Decoder.

I will try to read CV value's tonight and update later.

Also I will check Brian Lambert instruction as well before attempting again tonight.

Regards

[96RAF]

Not all decoders support read back, although the manual suggests it does as well as PoM.

Your best bet is to reset the decoder (may take a few goes) and check if it responds to address 3.

[Deem]

Update on reading the CV 7 Value of Bachmann Decoder,

Either decoder is dead or it is really cheap no function or ability to read.