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DCC SD-50 Athearn burns out lights fast!

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DCC SD-50 Athearn burns out lights fast!
Posted by cudaken on Sunday, August 24, 2008 8:21 PM

 I have a Athearn RTR DCC SD-50 ready engine that eats head lamps in 5 minutes or less. I am running a Digitrax DH123PS decoder. I have been using Athearn ATHG63843 lamps. Bag states they are for SD70-SD75. I bought them for a Athearn SD-45-2 after speaking with a person at Athearn. Thought if they would work for a SD-45-2 they might work in the SD-50. They have been fine in the SD-45-2 I will add.

 Here is the SD-50 that keeps eating the lights with the shell off.

 

 When I order the lights I told my LHS I want 6 lights, he thought I want 6 bags. Each bag has 4 lights so I have a few.Smile [:)]

 Am I using the wrong bulb, or wrong decoder? I have the same decoder in a little newer style SD-50 with no problems. It has 2 wires from each truck, not the metal arms with wires solder to it like the PIC I posted. One in the PIC came stock that way, not a kit bash.

 Could it be the printed circuit board?

 Thanks for the coming answers as well.

              Cuda Ken

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Posted by jeffrey-wimberly on Sunday, August 24, 2008 8:29 PM
What voltage are the bulbs? The decoder is probably knocking out 12 volts. If the lights are lower and they're connected without a resistor they'll blow every time.

Running Bear, Sundown, Louisiana
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Posted by cacole on Sunday, August 24, 2008 8:47 PM

The Athearn bulbs are 1.5 Volt and the decoder lighting output is 12 Volts.  You must wire a 1,000 Ohm resistor in series with each bulb or use a TCS decoder with the built-in voltage regulator for Athearn bulbs.

 

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Posted by river_eagle on Monday, August 25, 2008 3:00 AM

the Athearn quick plug board that the decoder plug into reduces the voltage, but the Athearn bulbs just are not very high quality, and I do not think they can handle much more than 1-1.25 volts for very long, and don't handle shock well at all.

I use the modelpower grain of sand bulbs, they have lens ends, as replacements as the Athearns burn out.

I have not needed to replace a modelpower bulb yet, except the ones blown by my own stupidity.

When I use them in other applications, I use a 820 ohm resistor for each bulb, 1000 ohms are too much and only just allow them glow.

another option is to install a 10 ohm resistor into the blue wire of the JST plug/harness (pigtail) that you have the decoder attached, the lights won't be as bright, but they will last longer 

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Posted by cudaken on Monday, August 25, 2008 7:47 AM

 Anyone have the right bulb part number? That should be a lot easier.

                 Cuda Ken     

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Posted by river_eagle on Monday, August 25, 2008 5:56 PM

I don't have the modelpower # handy, 146?, but the other brand I use is circuitron

there numbers are

7411, 7414, 7416, and 7418

they come in 2-6-12 packs

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Posted by locoi1sa on Monday, August 25, 2008 8:37 PM

Cuda Ken

 I magnified the pic and did not see any resistors on that board. What I do see is diodes for directional lighting. The 8 pin plug would bypass the diodes. I would scrap the board and hardwire the decoder with a couple 1K 1/4 watt resistors for the stock bulbs or go with LEDs.  

    Pete
 

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 I started with nothing and still have most of it left!

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Posted by cudaken on Tuesday, August 26, 2008 12:01 AM

 locoi1, good eye's there, well I think! Big Smile [:D]  My self, I would not know a resistors from a diode if my life depended on it. I just pulled out a Dash 9 board I have and it does look's a little driffrent than the one in the SD-50. I will pull the shell later and do a side by side.

 Thanks again, looking for the number to Athearn again, Cuda Ken         

I hate Rust

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Posted by jeffrey-wimberly on Tuesday, August 26, 2008 4:53 AM
 cudaken wrote:

looking for the number to Athearn again, Cuda Ken         

(310) 763-7140

Running Bear, Sundown, Louisiana
          Joined June, 2004

Dr. Frankendiesel aka Scott Running Bear
Space Mouse for president!
15 year veteran fire fighter
Collector of Apple //e's
Running Bear Enterprises
History Channel Club life member.
beatus homo qui invenit sapientiam


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