DCC decoder behaviour

Stephen D. Richards · February 12, 2007, 01:31:17 PM

I have a brand new Bachmann F40PH Phase III loco and first run it in DC and it worked very well. I then took a new Bachmann decoder and installed it in the loco. Not my first one! The loco began to run at a moderate pace with the throttle turned completely off. (EZ Command) When I put the controller on 10 I can control the throttle somewhat. It will not change directions nor will any of the other functions work. I thought maybe I had a bad decoder and tried another one. Same results. Anybody have any ideas here? thanks Stephen

Jim Banner · February 12, 2007, 11:43:19 PM

Is this a plug-in installation? Or is it a hardwire job? If it is a plug-in, then you could have a short between one or more connections under the board. Or a short in the wiring. Or you could have the plug not properly lined up with the socket. If it is a hardwire, then I would look for a misconnection or a short.

If you have a multimeter handy, you could measure the resistance between the motor connections and the pickup connections on the locomotive. Then between the light connections and the pickup connections. On this locomotive, the pickup connections are the halves of the frame. It is best to do this with the decoder disconnected. If it is the plug-in installation, you can either use a spare wiring harness to connect to the socket or pieces of solid wire the same size as the pins on the decoder plug. Smaller wire may not contact properly; larger wire may spread the socket pins so that they can no longer contact the decoder plug.

Stephen D. Richards · February 13, 2007, 07:08:15 AM

It is a plug/pin type installation. It is a new Bachmann engine. I will try the resistance measure. I had the feeling it may be the main board myself but don't know enough about them yet. Thanks for the information and I'll advise my findings as soon as I can get to test it, which may not be until this weekend. Thanks again, Stephen

Gene P. · February 13, 2007, 08:57:43 AM

As it is the Plug 'N Play type decoder, do you have it plugged in in the proper direction? If you install the decoder "backwards" it will not respond and behave strangely(on it's own). Make sure it's not plugged in backwards(I know because I've done this myself!).

Stephen D. Richards · February 13, 2007, 09:09:59 AM

Gene, thought of that too. It didn't make any difference when I switched them around. However, if my understanding is correct, the orange wire is the number 1 position, correct? I also thought maybe since the board is pretty intricate in this new engine that maybe the decoder is already instaleed! Who knows, so I tried it anyway. No functin of any sort with the plug out. Put the plug in and the engine runs great on DC. Any other thoughts or suggestions and I will give them a try. thanks for the assistance, Stephen

Jim Banner · February 14, 2007, 07:46:40 PM

Stephen, you mentioned that this is not your first installation. Would it be possible to temporarily install your new decoder in a different locomotive? One that you know works with a decoder would be perfect. If you get the same odd behaviour with that locomotive, then you know you have a decoder problem (sometimes bad ones do get shipped.) If your new decoder works fine in the alternate locomotive, then you know there is some problem with your new locomotive.

Stephen D. Richards · February 15, 2007, 09:33:59 AM

Jim, I'll try that this weekend. Unfortunitly, weekends are the only timeI have to work on them. Hadn't thought of that one...should have though! lol Oh well guess I gettin old! lol thanks for the info. I should have some more input by Friday evening! I just aching to work on it! Stephen

Stephen D. Richards · February 16, 2007, 04:04:57 PM

Jim and Gene,
just finished running this loco through some tests. Seems the board may be the culpret. The decoders work very well in other locos. I tested the eight pin female plug on the board with an ohm meter. point one and point eight had a significantly grerater reading than on two other locos that werre identical boards! The (I would assume anyway) normal reading on the good locos was .000 to .001. The reading on the bad board would change (I am assuming from my movement) from .003 to .040 on bothe pins. I haven't a clue as to what that means except the bad board has more resistance. At this point I am going to try and get a new board from Bachmann unless you all would know what I need to do from here. Thanks for you assistance, Stephen

Stephen D. Richards · March 03, 2007, 09:55:24 AM

Jim and Gene
Just an update; I received a new primary circuit board and installed it in the loco last evening. In about 20 minutes I had a new F40PH Phase III running around singing like a bird. I also installed an MRC sound decoder. So apparently you were correct and it was a board problem. Thanks for all your assistance. Stephen

P.S. for all those out there that are having problems with Bachmann service....I ordered this board and received it in one week! No problems. Thanks to Bachmann service personnel too!

Jim Banner · March 05, 2007, 05:45:47 PM

Glad to hear you got it up and running. Pin 1 is the right hand motor connection, pin 8 is the right hand wheels. If there is a leakage (lower than normal resistance) here, dc operation will not be affected but DCC operation can be as this means a partial wheels to motor connection, a no-no with DCC.

Keep in mind it was your diligent testing and your replacing the board that ultimately solved the problem. Gene and I just made suggestions.

Stephen D. Richards · March 06, 2007, 03:14:53 PM

Gene,
Without you guys I wouldn't have know what to look for! Let alone do any testing. Your information over this board has helped me considerably! I don't post alot but I read just about every day. Thanks again. Stephen

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DCC decoder behaviour