How do you test a mobile decoder board?

[Bart1701]

How do you test a mobile decoder board ( such as a Digitrax DN163A0 ) to determine if it is good? I have tried installing one in an Atlas N Gauge GP-38, but when I go to program it on my test track I get a "DNR" message when I try to read back any CV value.  Is there any easy way to test one of these decoders to make sure it is good?

The locomotive is OK - since it works fine when I put the original board back into the locomotive.

If the decoder is good, then what are some of the usual problems that could be causing this? The contacts from the motor appear to be making good contact with the brass pads on the bottom of the decoder. The decoder seems to fit tightly into the locomotive frame, but could there be an issue with the brass pads on each side of the decoder not making good contact with the frame - and how do you check this and fix it if this is the problem?

I have installed many decoders and have never run into any issues until now.

Thanks,
Bart

[bc6]

I'd start with the Digitrax troubleshooting guide below. Some people including myself put a blob of solder on the motor tabs.


http://ikm.digitrax.com/questions/1279

[Ian MacMillan]

Does your command station support readback of CVs?

[Bart1701]

Does your command station support readback of CVs?

Yes, I am using a Digitax Zephyr system and it will read back CV's in the programming modes. When I try to read back to decoder address, that is when I would get the "DNR" message on the console display.

Bart

[mmyers]

The usual problems with Atlas Plug and Pray decoder installations is:
1. poor or no contact at the two pads that slip into the frames
2. Poor or no motor contact with the decoder.

To improve frame/decoder contact add a little solder to the pads or do as I do and slip a leftover fret from a brass etching into the connection.

Motor contact is tougher. Sometimes they look good but are not. Sometimes they are good and wil slip out of place while running or transporting. Only foolproof way to keep them running is to solder little jumper wires between the decoder and motor contacts.

All of the above is why I usually just install a wired decoder in Atlas engines. I figure I'll be using the soldering iron anyway. May as well save a couple of dollars while I'm at it. GP38's have enough room under the DC board to slip a decoder in.

Martin Myers