# Problem with Digitrax DH123D!



## gc53dfgc (Apr 13, 2010)

I finished another DC to DCC loco today and wired everything properly but when going in forward the rear light turn's on instead of the front. The opposite happens when I put it in reverse. Is there a CV that I can change to correct this issue or is it back to the soldering iron for me? Also can the DH123D be wired with front and rear truck pickups or will this fry the decoder. I know the Bachmann decoders that come in the DCC equipped locos are made for this but I was doing a 44 ton switcher to DCC and the decoder fried I had both front and rear pickups for it and am wondering if this is not possible for DH123D's or DZ123's? All help is much appreciated.


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## dozer (Jan 2, 2010)

I have 3 of those decoders and everyone of them has the motor wiring backwards according to the instruction sheet.I have the same problem, so i just went in and swapped the motor leads around. I was having a problem of the engine moving opposite of selected direction, but the light was working correctly. I've had nothing but frustrations with those decoders.


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## NIMT (Jan 6, 2011)

Yes you can wire the pickup on both the trucks just make sure polarity is the same. As far as the lighting issue, it is probably just that the polarity or magnetic poling of the motor is off easy fix swap motor leads!


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## tankist (Jun 11, 2009)

yep. just flip the engine leads around and it will go in right direction. there is a CV for it as well, but i wouldn't touch it for now. 

and yes, you supposed to wire both trucks  electrical pickup is more reliable this way, as the other member said, just watch the polarity.


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## gc53dfgc (Apr 13, 2010)

ok I need some one to explain the polarity thing to me. I did a 44 ton switcher with front and back truck pickups and it fried. I made sure to keep the red wires hooked up to one side of the trucks and the black wires to the other side of the truck. Note that this engine had two motors in it also wired up to the decoder. Should I have linked the motors in chain or was making a T with the grey one end of the T going to raer motor and one to front and doing the same with the other end of the T or are you not supposed to have two motors wired to one decoder?


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## NIMT (Jan 6, 2011)

Keep all wheels on same rail connected to same power right red, left black and make sure that none connect to the motor by wire or via frame (old Athens). Always check with ohm meter to make sure motor contacts are isolated. Some dual motor drives use opposite magnetic poling. One turns clock wise one turns counter clockwise, with the wires connected to the same points. Others use same motor wired back wards. The safe bet is to hook up each motor individually to the chip to check rotation to make sure they turn the same direction with the wires in the same points if not swap one around.
What Brand was it? What scale? Did it run for a while or fry from the start? 
I have several dual engine units and they run great on a good chip set. NEC is better for dual motor amperage.
Sean


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## gc53dfgc (Apr 13, 2010)

It was an HO scale 44 ton switcher made by Bachmann Spectrum. The thing is so small I decided to go and get a DZ123 wired decoder from Digitrax for the thing. It had a 1 amp rating 2 amp peak. It seemed to respond correctly at first. It lurched forwards like it does when I first install a new decoder into a loco. Then when I slowly moved up the throttle it moved a little bit then stopped. Turned up the speed even more, then a beeping sound that generaly happens when a train derails happened. Hit the stop button on the controller cutting all power to the layout. I checked everything to make sure things were all good. Everything seemed ok so I turned power back on, beeping begins again and then the decoder starts smoking and almost catches on fire. It might have just been a decoder problem as this decoder I got from my local hooby shop instead of Traintekllc. The DZ123's had been sitting there for at least 5 or 6 years but one of the DZ123's looks exactly the same as another DZ123 so I could not tell if it had indeed been sitting there forever or just a week. I think I will reorder a new one from Traintek this time. You don't think digitrax would refund it or tell me what happened or are they not able to see what went wrong when it fries and almost catches fire.


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## NIMT (Jan 6, 2011)

I have the same model. Yep its a little tight in there, I would double check that the motor is completely isolated and yea if it is then most likely it was a bad decoder. I have about a 1 in 10 death rate on decoders. I have had better luck with NCE D13SR for small installs, And they replace bad ones no questions asked. I just think its a little tougher of a chip set.
Sean


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## gc53dfgc (Apr 13, 2010)

well I at the time of the install did not do anything to isolate them as they seemed completly isolated. I did modify the pickus so it did not touch the motor. I will definatly make sure everything is perfectly isolated with the new one even if space is super tight.


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