Hi everyone!
I am trying to install a Digitrax DZ125 in a 15 ton Mack switcher. When I first tried to use the decoder, the forward and reverse lamps worked fine, but when I put power to the motor all I got was a slight flash from the lamps and a minor jerk from the motor, and then nothing. The only sign of remaining life is when I lift the Mack off of the track and put it back on, there is a very brief flicker in the lights.
I built the drive train from scratch using Darth Santa Fe's example and I am using an NWSL motor. The drive train has very little resistance when turned by hand. When tested on DC the motor drew .14 amps at stall and about .04 amps at top speed. I have tested the unit for shorts and everything seems to be fine. The only thing I am not sure of is that the motor case is mounted directly to the brass frame. The motor leads themselves are completely isolated.
Is the motor mounting the culprit?
Any other suggestions? Did I let the smoke out? (If so I am really disappointed because there wasn't any actual smoke!).
Thanks
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
Sounds like the motor needs to be isolated, not just the leads. Have done a couple HO scale Athearns and the kit form digitax has the motor isolated from the frame by some rubber stopper looking things.
I think you're on the right track. One way to check is to use an ohm meter and check between the motor leads and casing, etc.
Sounds like a great project!!
Richard
Train Modeler I think you're on the right track. One way to check is to use an ohm meter and check between the motor leads and casing, etc. Sounds like a great project!! Richard
I and many others are guilty of making the statement, isolate the motor without giving details, other than nothing on the motor terminals.
I have a Walther's diesel with split frame and both motor halves are internally connected to the motor brushes. I had to isolate the frame and motor halves using Kapton tape and nylon screws. Kapton is much better than electrical tape. Thin and tough. My ohm meter showed me that they were connected.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Eric, Rich and Richard
Thanks for the quick resonses.
I am aware of the Athearn situation where one motor brush picks up power from the frame. I have converted an Athearn F7 successfully. I have also done Bachmann's Hogwarts Express where the frame and motor are essentially one unit. In both of those situations there was initially a solid contact between the track/frame and one brush, therefore the obvious need to eliminate that connection.
I have tested the Mack thoroughly and there are no connections between the track/ frame/ motor casing and the motor leads. I can't understand how having the motor case in contact with the frame would affect things but that is all I can see that could be wrong. Digitrax says that if there is a short the lights would flash on and off as soon as you put the loco on the rails. The lights did not flash and, as I said earlier, they worked fine. I was able to turn them on and off as desired.
Isolating the motor case is going to be a bit of a challenge! The motor is currently screwed to the frame in such a way as to allow the motor to swivel a bit to adjust gear lash. The screw is so tiny that a nylon replacement would likely not hold up, if they even make them that small. I guess it will have to be crazy glue and get it right the first time! I have Kapton tape but I will use .010 styrene to isolate instead so I can glue the motor in place.
I am going to contact Digitrax to see if they have any suggestions. Maybe if I am lucky it will turn out to be a bum decoder, but it was new in the original sealed package so that is unlikely. I have not played with the CVs because I don't want to leave the power on that long until I have a better idea of what is happening. The decoder warranty is a bust because I bought it through eBay, and besides the warranty replacement cost is about the same as the decoder.
Thanks again. I will keep you posted. This one is not going to put on the back burner - I'm too ticked off to quit now.
Have you checked your lights for short circuits?
I recently installed a decoder in an old Bowser Consolidation and the old headlight was grounding on the boiler.
Of course, that shorted out the whole system.
I found it by taking the loco apart - it would run fine until I place the boiler on the frame.
It's still not fixed all the way - the headlight is dangling from the front of the boiler so as not to cause a short.
I wish I was a headlight
On a northbound train
The motor case really does not matter as long as BOTH brushes are isolated from the motor case. The thing to check is for continuity from each brush terminal to the motor case and loco frame.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Problem solved! Turns out it was a dirty test track. My dumb! I had just cleaned the track but apparently not well enough. Anyhow, the wee beasty runs fine! I will post pictures soon.
Right now I am borrowing my son's laptop. I just purchased a new computer but it is not playing nice with these forums (problem posted on another thread).
Thanks again for your help and patience.
EDIT: Pictures posted in General Discussion. http://cs.trains.com/TRCCS/forums/t/204177.aspx