Speaker Wiring

[Stephen K]

Thanks for the resistor info Alan.  Walked into Radio Shack and walked out a moment later with a 5-pack of resistors for $1.50.  Such a deal.  Got everything installed last night and dropped it onto my test track. BEAUTIFUL!  I'm thrilled but with one big exception.  Neither of the lights work.    Everything else is fine but the lights, not so much.  I fear I may have wired them to the wrong leads on the connectors. 

Ring's wiring diagram for the LM3-S leaves a little bit to the imagination and I guess I imagined incorrectly.  I did some internet searching and found a diagram of the proposed NMRA color coding.  It seemed to agree with Ring's wiring diagram so I followed it.  Used the white lead to the front light, yellow lead to rear light and blue common for both.  All off the 9 pin connector, resistor on the white lead to the front LED.  No lights.

Is there something I need to do with the controller to activate the lights?  Or do I need to go back and rewire them differently?
     

[nodcc4me]

If you are using LED's in both front and rear you would need a resistor on both hot wires. If you place the resistor in the blue wire I believe you can get away with just one.


Go into your settings and make sure you have the correct light files on the appropriate buttons. If not, you will have to either copy them from the controller to the module or download them to the HC and then copy them over.

[Alan]

So that we have a common reference, here is LM schematic.

Does your wiring match?
What connections are you struggling with?

[G8B4Life]

If you place the resistor in the blue wire I believe you can get away with just one.

I would strongly advise against that. While it's possible to do because the resistor can indeed go on either the positive (blue wire) or the function ground wires (white, yellow, green or violet) if you put only one resistor on the blue wire instead of a resistor on each of the ground wires you would have to make sure you only used one output at a time; ever. Failure to do that would quickly result in the destruction of the resistor and the LED's being powered at the time, and possibly damage the LM too.

Alan could explain the "how and why" behind the destruction better if he'd like, I forget all the proper calculations to show it.

- Tim

[nodcc4me]

I haven't done it, and I wasn't sure. Thanks for the correction, Tim.

[Stephen K]

So I failed to mention, for clarity, the front light is LED but the rear light is incandescent.  Don't know, it's Just the way the loco came.  The LM wiring diagram Alan posted is for LED and there is another similar diagram for non-LED.  Basically the only difference between these 2 diagrams is the insertion of the resistors on the LED lights.

So I wired the rear incandescent light to the yellow lead with no resistor.  Wired the front LED to the white lead with resistor.  Connected both to the blue lead. 

[Alan]

If you place the resistor in the blue wire I believe you can get away with just one.

I would strongly advise against that. While it's possible to do because the resistor can indeed go on either the positive (blue wire) or the function ground wires (white, yellow, green or violet) if you put only one resistor on the blue wire instead of a resistor on each of the ground wires you would have to make sure you only used one output at a time; ever. Failure to do that would quickly result in the destruction of the resistor and the LED's being powered at the time, and possibly damage the LM too.

Alan could explain the "how and why" behind the destruction better if he'd like, I forget all the proper calculations to show it.

- Tim

Death and destruction is not quite right. A resistor in the blue wire will limit the total current that can flow irrespective of the number of outputs active at any given time. Each LED would get dimmer (non-uniformly) as more outputs are made active and their respective LEDs light.

Think of it this way: Imagine each LED as simply a zero resistance wire. The resistor determines how much current will flow in the wire. Adding more wires in parallel to the first wire doesn't make the electrical path any less resistive hence no increase in current flow. Just less current flowing through each individual wire.

Ultimately you are still correct, single resistor in the blue wire is a bad bad idea.

[G8B4Life]

Not to take this too far off topic...

Hmm, ok it seems like there is something wrong in my electronics theory there, which wouldn't be a surprise at that time morning (3am); or at all    . It looks like my reasoning that in parallel each LED would try to draw ~10ma (~14v - LED drop (3.5v) / 1000 = ~10mA) is false. If it were true and each did draw that amount then the 1000 ohm resistor would be trying to dissipate nearly 4 watts, way to much for a 1/4 watt resistor hence the frying, however a circuit simulation supports what you said Alan. I'll post the simulator later (appears to be a handy web based tool); I'm going to bed now, it's almost 04:30 and I'm making a lot of spelling mistakes as I type!

- Tim

[Alan]

Not to take this too far off topic...

Hmm, ok it seems like there is something wrong in my electronics theory there, which wouldn't be a surprise at that time morning (3am); or at all    . It looks like my reasoning that in parallel each LED would try to draw ~10ma (~14v - LED drop (3.5v) / 1000 = ~10mA) is false. If it were true and each did draw that amount then the 1000 ohm resistor would be trying to dissipate nearly 4 watts, way to much for a 1/4 watt resistor hence the frying, however a circuit simulation supports what you said Alan. I'll post the simulator later (appears to be a handy web based tool); I'm going to bed now, it's almost 04:30 and I'm making a lot of spelling mistakes as I type!

- Tim

Tim, I love that you reason through the problem.

However, it appears one of your fundamental assumptions is flawed. No component "draws current" even though that is the common lingo. There is no suction, vacuum, or otherwise negative pulling force. Rather, components "flow" what is available to them.

How's this for an analogy... a bucket full of water has a 1" hole in the bottom that drains into another bucket below. Does adding more buckets below for the water to drain into increase the rate of water leaving the upper bucket?

As the resistor (hole in top bucket) is setting the total flow, adding components (buckets below) simply divides that flow across each of the components. The total current (volume of water) doesn't change. Each lower bucket simply gets a percentage of the available water. Hence why LEDs get dimmer as you add more of them when flow control (resistor/hole) is on the supply line (blue wire/top bucket).

[Alan]

So I wired the rear incandescent light to the yellow lead with no resistor.  Wired the front LED to the white lead with resistor.  Connected both to the blue lead.

That should work.

HC button assignments?
Bulb and LED known to be good?
Solder / plug connections known to be good?

[Stephen K]

That's what I though too, should work.  The lights worked last I use that loco, before the move so a couple years ago of it living in a box.  I was pretty confident in the solder connections as I was doing them.  Packing the wires into final position could have broken one loose.  Only way to know that is pull it part and work thru it.  Not sure about the HC button assignments.  New to the program having just received it last week and turned it on for the first time last night I'm just beginning the learning curve.  Any quick guidance on the topic would be appreciated.  Otherwise I'm about to sit down with the manual and see if I can find anything about it.  Don't want to tear it all apart until I've exhausted "setting"' issues.
Thanks again for all the help!   

[Alan]

Refer to pages 14 and 15 in the HC manual.

With the loco powered on the track, do you get a little green dot appear on the light button when you press it?

[Stephen K]

yes, green light on the buttons.  I just opened it up and checked all connections are solid.  One original wire on the front light is questionable, might be broken.  But that shouldn't affect the rear light.  Since both don't work it almost has to be with the blue common but it all is solid. Next step may include cutting wires to check the incandescent light with a battery source.  Who knows. maybe that light is dead and the wire is broken on the front LED. 
 

[faithie999]

yes, green light on the buttons.  I just opened it up and checked all connections are solid.  One original wire on the front light is questionable, might be broken.  But that shouldn't affect the rear light.  Since both don't work it almost has to be with the blue common but it all is solid. Next step may include cutting wires to check the incandescent light with a battery source.  Who knows. maybe that light is dead and the wire is broken on the front LED.

when you re-do whatever wiring you think you need to do, test everything with the shell off.  if all is good, you can tape and carefully pack everything into the shell.  IMHO, stuffing everything into the shell and reassembling it onto the body is the hardest part of the whole operation!


Ken

[Alan]

Handy trick for in-service wire testing...

Use small needle to puncture the wire insulation and make contact with the conductor inside. Test clips on the needle to multimeter, bulb, whatever. The vinyl insulation will self-heal when the needle is withdrawn.