I'm trying to install a Digitrax DZ123 in a Bachmann N Scale Dash-8. I soldered the red and black wires to the pickup from the track and the grey and orange wires to the motor tabs. The system recognizes a decoder's there (it will read it and write to it) but the loco doesn't move when power is given. I figure something's wrong with my connection of the orange and grey wires. I'm wondering if I reversed the polarity. How can I tell which is the + contact and which the - contact for the motor? Also, am I correct in thinking that the loco should run even if the blue and white wires aren't hooked up to the lights? Thanks.
DCC is a +/- 12 volt AC system, not a DC system. The decoder converts the AC wave to DC power for the motor as well as reading control information from it. The motor is reverseable... in most recently manufactured locos they refer to the motor contacts as top and bottom. When wired according to the directions the loco will run forward when forward is selected on the DCC controller. If you got the wires backwards it will run in reverse. You don't need to resolder the wires or change the motor brush caps, you can reverse "forward" direction by changing a CV. In any case, you can't damage the decoder by reversing the orange and gray wires. You say it doesn't run at all. This could be due to a cold solder joint on a brush cap (or motor tab if that's where you soldered them). It could also be something as simple as you haven't selected the correct loco address so the throttle info is being sent to a non-existent loco. You say it reads and writes, are you still in programming mode? Sorry... don't mean to sound patronizing... just trying to cover all the possibilities. Now that I think about it, someone had a thread here in the last couple days about a DZ123 that wouldn't work after being assigned a 4 digit address. You might look at that thread, but I don't recall anyone else saying they'd seen the problem before.
Yes, I made sure that I had the address selected. I will have to try the 4 digit address issue because before trying to run it I did give it a 4 digit address. On another forum someone suggested that I may not have the motor isolated. This confused me because it's a split frame loco and I thought that meant the motor was already isolated.
Split frame does not indicate the motor is isolated. It's just the way the frame is designed which usually makes it easier to convert to DCC. But the motor will still have a pair of tabs coming off of it that touch the frame halves which is how it picks up its power. If you have not removed these tabs then the motor is still contacting the frame halves which means you've created a dead short through the decoder and probably let out the magic smoke. You need to remove the motor tabs to isolate the motor as well as make sure that the soldered wires on the brush caps can not touch the frame either by using Kapton tape or machining out a little bit of the frame for clearence.
I didn't go into motor isolation because Ken didn't mention a short, just that the motor wouldn't run. (A short is kind of a hard thing to miss ). But yes, mavrik0 explains the isolation issue well. Some people solder to the motor tabs instead of removing them. This is a common way shorts occur if the tabs aren't insulated properly with Kapton tape. Like mavrick0 I prefer to remove the tabs and solder directly to the brush caps.
Try changing cv29 to 34. I had that same problem, with four digit add. I think I found this on Digitrax web site. I 've converted two Bachmann Dash 8's. with DZ 123. One other thing you might try, is reset it the default settings, and see if it will run. If it does, and I hope you have Decoder pro, I think it's under tools, there is single CV programer. Also I think at Tony's trains, there's a link to a little program to figure out the values for CV 17 & 18, these two CV's are the 4 digit add. Bruce
Just as a further sanity check, can you make the lights go? i.e. if you turn the headlight on/off on the controller, does the loco's headlight turn on/off. If it works on the programming track (you can read and write the decoder) but on the main you can't even turn the lights on/off, then you've probably got a problem addressing the loco - long versus short address, for example. If the lights work but the motor don't, you've possibly got a problem with motor isolation. Be Careful! it is possible (especially in N) to destroy a decoder by having the motor shorted to the chassis Just my 0.025c (inflation)
One other thing to check is the motor brush holders (Caps). If these were over heated while soldering the wires to them the brush holder(s) may be out of alignment. Try cutting the gray and orange wires from the decoder (long enough on either end to reconnect) and hook the motor to a normal DC power pack to see if it runs. Be sure not to short out any of the other decoder wires while testing.
Or, you may be overlooking the simplest thing of all- clean the loco wheels. I've had locos do the same thing- program on the program track but not run on the main. A good wheel cleaning- even on a brand new loco- can work wonders. DCC is much more sensitive to having clean wheels and good electrical contact.
Ken, Is this the new DCC ready version? If so, see the diagram at this link: http://www.bachmanntrains.com/home-usa/dwg/dwgs/N850X-IS001_2.PDF Orange wire goes to pad 1, grey wire goes to pad 5. If you reverse them, it will just run the wrong way but still run. Blue, white, and yellow wires don't need to be hooked up but should be insulated so their ends do not touch each other or anything else while testing to prevent blowing the decoder. I'd try resetting the decoder. write and 8 to CV8. You won't be able to read the value, it will just reset. Chances are a wrong address has been prgrammed or CV 29 is set wrong for the address programmed. Martin Myers
