# Appropriate LED for Digitrax HO SDH164D



## Artieiii (Apr 25, 2011)

I am in the process of adding DCC/Sound to my HO scale Bachmann Plus GS4 4-8-4 SP Daylight. I purchased a Digitrax HO SDH164D controller and I have it mostly installed in the engine/tender. In the process of taking the engine apart I broke the incandescent headlight bulb so I need a replacement. I would like to go the radio shack and buy an LED to replace it. What should I look for? Do I need to add a resistor? I guess I need one that can operate at 12v but when I was in the store I only saw small ones rated at like 3v. These are the last 2 connections I need to make to the controller. Thanks in advance.
-Art


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## Artieiii (Apr 25, 2011)

This is what radio shack has:
http://www.radioshack.com/product/index.jsp?productId=3060980
It's rated as FW current 25mA; FW supply 3.3 (typical), 3.6V (maximum)
I assume I will need to add a resistor to make it work but I don't know what to get. Please help.
-Art


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## gunrunnerjohn (Nov 10, 2010)

If you had a 12V bulb, first off you will need a resistor. I'd run that LED at something less than 25MA, and figure the resistor has to drop around 9V. Let's say 20ma at 9V, make it a 470 ohm 1/4W resistor should do it. This is DC coming out, right? Never know with DCC, since the actual track voltage is a chopped AC.


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## Artieiii (Apr 25, 2011)

gunrunnerjohn said:


> If you had a 12V bulb, first off you will need a resistor. I'd run that LED at something less than 25MA, and figure the resistor has to drop around 9V. Let's say 20ma at 9V, make it a 470 ohm 1/4W resistor should do it. This is DC coming out, right? Never know with DCC, since the actual track voltage is a chopped AC.


 Gunrunner:
Like this?:
http://www.radioshack.com/product/index.jsp?productId=2062342
Does it matter which side the resistor goes (+ or -) lead?

The controller instructions do not say what comes out of the light leads (DC or AC). It does not even say how much voltage or amperage comes out of the light leads. The only thing I can find in the instructions is "6 function FX3 200ma outputs."
-Art


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## gunrunnerjohn (Nov 10, 2010)

For AC, you'd really need a diode and a lower value resistor, since you'd be getting about half the effective current, that's why I mention AC vs. DC. Someone here must have experience with those decoders and know what they put out. I know that for O-scale, some lights are AC, some are DC, it all depends on the TMCC package what they generate. You can use a diode to determine if it's AC or DC, if the LED lights with the diode in one way but not the other, it's DC. If it lights both ways, it's AC. Of course, the diode has to be oriented correctly for the LED to light at all.

The resistor you show is right. FWIW, I run my headlights at around 15ma, still very bright, but not overpowering. You might try a 560 or even 680 ohm resistor instead of the 470 and see if the brightness of that is good. You can "tune" the intensity of the light with the resistor value. I mention those specific values as they're the commonly available values in 5% steps.


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## Artieiii (Apr 25, 2011)

Gunrunner,
It's really annoying that the instructions do not say what the light output is. Any harm done if I install the LED and resistor and it's AC or DC (I do not want to fry my new decoder). I really want to finish up this job and run my engine again soon but I don't want to make a fatal error. My soldering technique has been improving. So far all my connections look great! 
Thanks again
-Art


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## Artieiii (Apr 25, 2011)

Gunrunner,
How bout these Radio Shack micro-lamps. They are incandescent 12v 60mA bulbs. Would these work without resistors? Incandescent's would not matter if the current was AC or DC right?
http://www.radioshack.com/product/index.jsp?productId=2103780
-Art


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## gunrunnerjohn (Nov 10, 2010)

The RS incandescent bulbs would work fine if you want to go that way. 

FWIW, I've run across a number of things just like this with add-on electronics. I was told by one company that anyone that was going to install their kit should know how to determine what the output was. That kind of response really chaps my butt! I knew how to determine it, but I shouldn't have to go to the trouble. Besides, I have to have the product installed and operating to get the outputs working, and I wanted to wire the shell with lighting while I waited for the kit. In the end, I took another locomotive apart that had the same package and checked the output. It took me probably 45 minutes to do what they could have done with a few keystrokes in their documentation! 

I think some companies just don't get it.


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## Artieiii (Apr 25, 2011)

Gunrunner,
I used these radio shack incadescents mini lamps:
http://www.radioshack.com/product/index.jsp?productId=2103780
They did not require any resistors to work properly. This is a good find as just about everyone has a radio shack nearby.
The project was complete all worked except I wired the motor backwards and the headlight came on only in reverse. I took it apart and reversed the motor polarity now the engine does not spin in either direction. Not sure what to do next. I guess I have to take it apart again and test the engine with DC power. The sound and light work properly so I am pretty sure I did not fry the decoder. I guess it could be my solder connections on the motor but they looked great and I tugged on them and they seemed solid. Any suggestions?
-Art


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## gunrunnerjohn (Nov 10, 2010)

Well, first off is to test the motor with nothing connected, though I suspect that will work. The bad news is, you could have damaged the motor drive of the decoder and it would still run the lights. Not saying that's what happened, just pointing that out. 

If the motor itself runs fine, connect the meter to the motor when you try to move the train and see if you see voltage in either direction. FWIW, shorting the motor leads is likely to cook something if that could have happened.


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## Artieiii (Apr 25, 2011)

gunrunnerjohn said:


> Well, first off is to test the motor with nothing connected, though I suspect that will work. The bad news is, you could have damaged the motor drive of the decoder and it would still run the lights. Not saying that's what happened, just pointing that out.
> 
> If the motor itself runs fine, connect the meter to the motor when you try to move the train and see if you see voltage in either direction. FWIW, shorting the motor leads is likely to cook something if that could have happened.


Well that just plain sucks! At least it's a digitrax decoder....I may have to utilize their "no worries" warranty. So when I get home I will disassemble once again remove the motor and test it on DC power. If it does not work I need a new motor. If it works it's either my solder connections or the decoder motor function is fried. If I get voltage from the motor leads then the decoder is fine.....if not then call Digitrax. Thanks Gunnrunner. I did not realize that individual parts of the decoder could fry and the rest still works.
-Art


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## gunrunnerjohn (Nov 10, 2010)

Yep, I've toasted the drivers for a TMCC board, and the lighting circuits still work, but a short to one motor lead to the frame took out the drivers.

I was fortunate that I could pop a new set of drivers on and move on. I'm also a lot more careful about looking at the connections to the motors on a conversion, I confess to having not looked that close.


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## Artieiii (Apr 25, 2011)

gunrunnerjohn said:


> Yep, I've toasted the drivers for a TMCC board, and the lighting circuits still work, but a short to one motor lead to the frame took out the drivers.
> 
> I was fortunate that I could pop a new set of drivers on and move on. I'm also a lot more careful about looking at the connections to the motors on a conversion, I confess to having not looked that close.


I was very careful but the way the motor sits in the frame it hides the wires from view. I hope it's not toasted but I think that's the likely scenario. At least it only cost me $39. BTW this cheapie digital sounder really does not sound bad at all. It's no Tsunami for sure but I am satisfied with the sound quality for the price.
-Art


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## gunrunnerjohn (Nov 10, 2010)

It just takes one short...


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## Artieiii (Apr 25, 2011)

gunrunnerjohn said:


> It just takes one short...


Update for you Gunrunner,
I ordered a new controller so I took my GS4 apart (again). When I tested the motor with DC power nada. I guess the controller is ok, I must have burned up something inside the motor with the soldering iron. Damn, now I got to wait for a new motor from Bachmann.
-Art


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## gunrunnerjohn (Nov 10, 2010)

It's surprising that you killed the motor, they're usually pretty hard to kill unless you break off one of the power connections.


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## Artieiii (Apr 25, 2011)

Gunrunner,
I was very careful, no tabs visibly loose. I did not feel like I used excessive heat. I really don't know how this happened. I went to the bachmann site to order a replacement motor but the replacement motor/chassis assembly is no longer a split frame design. I don't know if it will fit my older shell. I posted on the Bachmann message board to see if anyone can help me.
-Art


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## gunrunnerjohn (Nov 10, 2010)

You may be able to find a motor on eBay or with parts distributors. Are you "sure" the motor is bad, that's very unusual.


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## Artieiii (Apr 25, 2011)

Well I hooked it to my DC transformer leads and nothing happens no noise, no smoke nothing with forward or reverse current. The worm gear/shaft spins freely. I will try to solder leads to the motor to make sure I have a good connection (I just tried touching the wires to the terminals multiple times). I am baffled. 
-Art


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## gunrunnerjohn (Nov 10, 2010)

Well, take ALL the other wires off the motor, then clip the transformer directly to it. Also, don't give it too much voltage, most can motors don't like excess voltage. A few volts is more than enough to see if it runs.


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## Artieiii (Apr 25, 2011)

gunrunnerjohn said:


> Well, take ALL the other wires off the motor, then clip the transformer directly to it. Also, don't give it too much voltage, most can motors don't like excess voltage. A few volts is more than enough to see if it runs.


Nope, that's what I did already, no wires on it.....just 2 jumpers from the transformer directly to the terminals.....nada...zilch....no smoke, no humming no motion. Sometimes it sucks to be me.
-Art


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## gunrunnerjohn (Nov 10, 2010)

Well... sounds like the motor.


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## Artieiii (Apr 25, 2011)

gunrunnerjohn said:


> Well... sounds like the motor.


Well on the bright side, I guess the controller is probably ok!
-Art


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## gunrunnerjohn (Nov 10, 2010)

Unless it took out the motor.  :laugh:


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## mopac (Feb 24, 2011)

Its stories like this that scare me on doing conversions. I do want to
go DCC but I have too many DC locos and want to convert them. I do hear 
stories that all went fine. Looking forward to doing some conversions. I don't 
have a DCC system so don't need to do any yet. Artie, is this your first
conversion or have you done some before? Glad to hear you like the sound
from that digitrax decoder. Thats the one I want to try first. Good luck and
please keep us updated on whats going on with the loco. I am surprised the
motor is fried but I guess anything can happen.


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## mopac (Feb 24, 2011)

(hand up in the air). Remember I have never done DCC.
When Artie first wired the motor it ran backwards, could
that have been changed with programing the decoder?


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## gc53dfgc (Apr 13, 2010)

In some instances of decoders Mopac the light outputs can be changed while leaving the motor polarity the same but it is ussually easier to just unsolder, switch the wires, and resolder them on then do all of the CV work just to achieve that. I am offering my services of installing DCC and DCC/Sound decoders into locomotives and adding super details onto the locomotives as well. PM me if you would like me to take care of the installs for you when the time comes and we can work on the price.


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## gunrunnerjohn (Nov 10, 2010)

It's very unusual for a motor to bite the dust, they're usually a lot more robust than the electronics. Don't know what happened to Art's motor, but it's hard to believe that it had to do with the update.


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## gc53dfgc (Apr 13, 2010)

I have a feeling something blew out on it like say a spring that holds a brush in perhaps. I have had that happen to me a number of times while cleaning them or switching their polarity. It is also possible something got jammed in it like a piece of metal or something and is preventing it from running but if that is the case then it should make some sort of humming sound I would belive.

I have motors going back to the 60-70s that arrived to me barly running or not at all and after a simple cleaning they all run like new so I have a hard time imagining you destroying your motor.


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## gunrunnerjohn (Nov 10, 2010)

I have taken a couple of old DC motors apart and fixed them, though it depends on how they're built.


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## gc53dfgc (Apr 13, 2010)

Every motor I have ever seen I have been able to take apart and fix to like new condition.


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## gunrunnerjohn (Nov 10, 2010)

Well, I've seen some of the cheap ones that you'd have to do serious damage to in order to disassemble them. I suppose you could if you really wanted to, but in those cases I simply replaced them.


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## Artieiii (Apr 25, 2011)

gc53dfgc said:


> I have a feeling something blew out on it like say a spring that holds a brush in perhaps. I have had that happen to me a number of times while cleaning them or switching their polarity. It is also possible something got jammed in it like a piece of metal or something and is preventing it from running but if that is the case then it should make some sort of humming sound I would belive.
> 
> I have motors going back to the 60-70s that arrived to me barly running or not at all and after a simple cleaning they all run like new so I have a hard time imagining you destroying your motor.


Well since Bachmann does not use the same motor in the newer design (so no replacement is available) It is possible that they use that motor in other models but I do not see anywhere on their web page any shows if it is swap able. I will try to take it apart and see if I can do something. 
-Art


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## Artieiii (Apr 25, 2011)

*Digitrax HO SDH164D in Athearn Blue Box GP40*

Well I started on my second DCC/Sound conversion. I installed a Digitrax HO SDH164D controller in my step son's Athearn Blue box GP40. It was a very tight squeeze to get the speaker and controller in that narrow body. I know it's a cheap decoder and the sound is not great but it needed sound to keep my step son happy. My first successful conversion.
-Art


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## gunrunnerjohn (Nov 10, 2010)

Great, it can be done.


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## Artieiii (Apr 25, 2011)

Well Gunrunner, I figured out the problem. While soldering the leads on the motor, I lost one of the brushes/springs. That's why it won't run. I called Bachmann and since they don't make that style motor anymore they have no replacement parts. The service tech said I could send in my model and they will send me a replacement with DCC onboard for $40. SWEET! Then I will have to call soundtrax and see what they suggest for adding sound to the tender. The newer style tender has a speaker enclosure so it should be pretty easy to do. Thanks for all the help. 
-Art


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## tjcruiser (Jan 10, 2010)

Any chance of finding the lost spring/brush on the floor somewhere?


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## Artieiii (Apr 25, 2011)

tjcruiser said:


> Any chance of finding the lost spring/brush on the floor somewhere?


I looked all over, found the spring no brush then I dropped it again can't find it now.
-Art


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## tjcruiser (Jan 10, 2010)

Bummer ...


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## gc53dfgc (Apr 13, 2010)

Get me a picture of the motor you have and that will tell me what spring and brushes you need.

Also, Called it!


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## Artieiii (Apr 25, 2011)

gc53dfgc said:


> Get me a picture of the motor you have and that will tell me what spring and brushes you need.
> 
> Also, Called it!


Wow gc53dfgc, 
That's a generous offer. I found a solution to my issues. Called Bachmann and they said they don't make that style motor anymore so I could mail them my train and $40 and they would send me the newer version with DCC onboard. Now that's some fine warranty. Next step will be to add a tsunami sound board to the tender.
-Art


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## gunrunnerjohn (Nov 10, 2010)

I'll bet you can get them. As far as the spring, just "sweep" the floor with a magnet, you'll find it an probably a lot of other stuff.


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## Artieiii (Apr 25, 2011)

gunrunnerjohn said:


> I'll bet you can get them. As far as the spring, just "sweep" the floor with a magnet, you'll find it an probably a lot of other stuff.


Gunrunner,
Already shipped the train off to Bachmann for a warranty replacement.:thumbsup:
-Art


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## gunrunnerjohn (Nov 10, 2010)

Well, that's another way to do it.


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## Artieiii (Apr 25, 2011)

*Replacement GS4 from Bachmann*

I got a postcard in the mail today from Bachmann Trains. They said that my replacement GS4 SP Daylight with DCC onboard will be sent out in about 6 weeks.:thumbsup::thumbsup: Time to put some money aside for a Tsunami sound board.
-Art


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