Question on DCC 0-4-0 Davenport

[Plow_Bender]

Hey all,
Recently began converting my models over to DCC and acquired decoders for my smaller locos.  I put one in the Davenport I have and after programing it found that the model runs fine with no issues.  However, the headlight on the model will not turn on.  I've tried turning it on through the DCC controller, but with no luck.  All my other locos have lights that turn on, but the Davenport seems to be a no go.  I purchased a new PCB and headlight when I got the model, so I don't feel that it's either of those causing the problem.  Any help would really be appreciated.

-Rusty

[Hunt]

The usual suspect with no headlight control is the decoder is not plugged in correctly.  Unplug the decoder from the PCB 8-pin socket and turn 180.  Number one pin goes in number one socket.

That not help, then test the connections Click Here for testing instructions.

[Greg Elmassian]

Good call, this has happened before.

[Plow_Bender]

Problem solved, Hunt.  As you suspected I had the decoder plugged in backwards.  Turned it around and the light now turns on and off with the control and also when the model is in reverse.  Unfortunately DCC is still very much new to me so I'm still learning.  Thanks for the help!

-Rusty

[Plow_Bender]

Got another question.  I installed a decoder in Bachmann's 0-4-0 Porter and noticed that the headlight comes on, but you can't turn it off.  It's not a big deal, but I'm just wondering if it means I wired something in wrong?  In addition to that, I can't seem to have any control turning the smoke unit off.  I noticed that the smoke units on my Lyn and Davenport aren't even turning on, but those have the plug in boards.  Anyone know anything on this issue?

-Rusty

[Greg Elmassian]

The headlight should go on and off with F0, nothing happens?

I don't think the smoke unit is wired into the decoder at all. There is a separate smoke switch.

[Hunt]

Got another question.  I installed a decoder in Bachmann's 0-4-0 Porter and noticed that the headlight comes on, but you can't turn it off.  It's not a big deal, but I'm just wondering if it means I wired something in wrong?  In addition to that, I can't seem to have any control turning the smoke unit off.  I noticed that the smoke units on my Lyn and Davenport aren't even turning on, but those have the plug in boards.  Anyone know anything on this issue?

-Rusty

Rusty,
Yea -  wiring issue(s).

Click Here
Scroll down
Note the difference between the DC vs DCC Wiring Connection



BTW --- What DCC decoder did you install and what DCC system are you using?

[Plow_Bender]

I did hook things up according to the DCC wiring diagram.  The decoder I installed was a 1amp decoder from Bachmann #44915.  At the moment I am using a Bachmann Dynamis system, but I recently upgraded to a MRC Prodigy Elite which I'm currently waiting on to arrive.

-Rusty

[Greg Elmassian]

So the smoke unit lead comes to the DCC decoder interface.

What is not shown is the actual circuit, clearly one lead of the smoke unit goes to the decoder, the other lead is connected to what? +5v, rectified track voltage? The decoder common?

Looking at the interface, there is no provision for the decoder common, so the inference is that the LED and the smoke unit have their "other" leads connected to the track pickups, most likely through a diode.

I would try to trace both leads to the smoke unit (and the LED) and verify this.

I'd also connect the smoke unit to the DCC power (through a full wave bridge) and see how much current it draws.

My best guess is that the smoke unit probably draws 1/2 amp and exceeds the current rating of your decoder.

Please indicate the make and model of decoder used.

Greg

[Hunt]

. . .

Please indicate the make and model of decoder used.

Greg

I did hook things up according to the DCC wiring diagram.  The decoder I installed was a 1amp decoder from Bachmann #44915.  At the moment I am using a Bachmann Dynamis system, but I recently upgraded to a MRC Prodigy Elite which I'm currently waiting on to arrive.

-Rusty

Greg Elmassian,

Click Here
Bachmann decoder info

[Greg Elmassian]

OK,

1. the documentation on the loco specifies 8 wires, but does not assign any pin numbers to any socket.

2. your documentation on the decoder specifies that the function outputs have a limit of 100 ma

3. by deduction, the smoke unit wire must be connected to the rear headlight output

3. I doubt seriously that the smoke unit is 100 ma... but test it at track voltage.


Do you have a wiring diagram, i.e. which pin of the decoder is connected to which wire on the loco?

In any case my opinion is unchanged, the smoke unit current draw exceeds the decoder capability.

Greg

[Hunt]

If the PCB is wired correctly by Bachmann the smoke generator current requirement is not an issue.

We know it is common for decoder function output limit to be 100mA of current and this is not enough power to operate the smoke generator directly.  We can deuce from the Davenport DCC Wiring Connection drawing  the smoke generator is either  wired to the track pickups or to the motor outputs with relay and diode in circuit making the  decoder function output just an on and off control for the smoke generator.

Need to wait until the MRC Prodigy Elite is being used and is still an issue focus on why the headlight cannot be controlled.

================

I am off doing other things, so it will be awhile before I read this thread again.

[Plow_Bender]

Well I first want to apologize for taking so long to get back to everyone, but I haven't really had time to do anything to give any updates.

So the MRC system arrived and I tried running the Porter with it, but I still have no control over turning the light on or off and the same can be said for the smoke unit.  I had the model running for probably around a good 20 minutes before the smoke unit even started to work, and then after turning off the switch the unit still continued to smoke.  That being said, I'd assume I've got no control over that be it with the DCC unit or the switch on the model.  So once again I'm left asking questions.

I'm also noticing issues with my Peter Witt street car and the Lyn.  Both models use Bachmann's 44915 decoder.  The Peter Witt has no interior lights, but the headlight and rear light come on depending which direction the model is moving.  The Lyn on the other hand appears to have the issue of the smoke unit not functioning even when the switch is in the on position.  I'm not 100% sure without testing, but I'm wondering if my Davenport has the same problem?

I'm not sure what the problem is.  I've installed a similar decoder in my Rail Truck and haven't had any issues, so whats wrong with the other models?  Do I have a defective decoder?  Did I wire it in wrong?  Do I have the right decoder for the model?  I really wanted to add DCC to my railroad this year, but now I'm starting to wonder if I've just over-complicated the hobby...

-Rusty

[Greg Elmassian]

I think we have established that the smoke unit is not controlled by the decoder.

So you need to check the wiring to the smoke unit, and the unit itself. They can burn out if run dry.

Voltmeter time.

Greg