As you can tell by the attached photo I'm having a recurring problem! This is the backside of a pair of DZ123 decoders that I installed in a Bachmann H16-44. The first was installed several months ago and run for a fair bit of time before unexpectedly shorting the command system and smoking itself. Installing the second decoder, I decided to put extra tape around the motor to make sure it was isolated from the frame. It took programming, but when I put it on the track, it shorted and smoked itself the moment I tried to move it, although the other function outputs remained intact and I was able to control the lights normally. I emailed Digitrax for help, but I was hoping someone here might have some experience on the matter!
Is there maybe a small metal part causing a short like on one of the trucks? Perhaps a stray loose wire is making contact at times and causing a short.
No, one of the first things I checked for was shorts. There's no conductivity between the frame halves, nor between the frame and the motor on either side.
It is very hard to tell just what is going on by your description. Need to have the unit in hand to trouble shoot? Maybe a pro installer is needed.
It is rare but it is possible that the motor has an internal short. I have only ran into this once and that was on a Kato. The two DZ123's that motor wrecked looked a lot like your DZ123's. I suggest removing the motor and connecting it up to a DC throttle with a milliamp meter in series and get a current reading. Should not be more than 200-300 ma. Here is a post I made my blog on that one. Kato C30-7 with shorted motor I've also done a couple of the Bachmann H44-16 and used the DZ123 for that. Here is a link to that installation. DZ123 in a Bachmann H44-16.
Shell on or off? I had an issue with a VO 1000 where the shell was pushing the LED leads against the frame. Ben
Digitrax indicated that it may be caused by motor overcurrent. The link Brad posted looks very similar, so I think it's very likely that it's a motor issue. Anyone know how to troubleshoot one? :-/ Incidentally, I installed it using the existing PCB. I may hardwire it next time.
measure the motor current seem like a good way to see if you are over the current limits of the decoder? A $5 meter will do it ok, even if it is PWM ... won't be real accurate but should give you a rough idea.
with the light functions still working this is most definitely a short from the motor to the frame, i've had several of these even from some loco's with drop-in decoder capability (intermountain) once you solder your wires to the motor tabs, you need to wrap then with kapton tape to fully isolate them from the frame. and a roll of kapton tape will cost less than $2 on eBay with free shipping choose either the 7.5mm or 10mm width one roll will last you for years.
Well Kapton tape is great stuff if the install is not correct it is like using band-aid on a broken leg- sending PM.
