Does a bad LED open the circuit?

Model Railroader Electronics and DCC
1

One of my Totroise controlers stopped working.

Here is what I am getting.

1.10vdc from power supply

  1. 10 vdc across end pins

  2. LED’s on Control panel out

  3. 0 Voltage on line going to Tortoise

If an LED is burned out would that cause this problem?

And if so how can I check it?

2

Yes, a bad LED could cause the Tortoise not to work. You can easily check by just bypassing the LED with a pair of clip leads.

3

Thanks mister B. That was the problem. Now I Just have to choose the riht bulb.

4

Just curious. Did the LED have a resistor on it?

Rich

5

the tortoise machines draw about the same amount of current an LED requires and needs no resistor

6

No. These were put in years ago. I will remember to use one now.

Thanks

Harold

7

Not everyone wires LEDs directly to Tortoises. I don’t. I just wire the LEDs to the center tabs of the DPDTs on my control panels. In that case, resistors are required.

Rich

8

As Greg mentioned, the resistor is not needed. If the LED was not wired inline with the tortoise, it would be needed, but if that were the case, the tortoise would not have stopped working.

9

I remain curious.

Are all the LEDs “out” on your control panel?

Rich

10

I’ve had a couple of the indicator LEDs fail on some of my Tortoise iinstallations. Yes, they open on failure. One downside to the “supply chain” for model railroaders is that much of the discounted electronic components available to us are not exactly certified, first-quality products.

Being in series, anything within the circuit, including other panel LEDs will also be extinguished. Sure, there are several methods to wire indicator and/or signal lights to a Tortoise but the in-series arrangement is a quick and easy solution.

I use two lead bi-color LEDs and in some cases I have up to three daisy-chained along the circuit. With over a hundred Tortoises I’ve probably only had two or three LEDs fail in 25 years.

I keep dozens of bi-color LEDs on hand. Some red/green and others red/amber both in 5mm and 3mm. For signaling and frog powering, those that are not powered off of Frog Juicers, I do use the auxiliary contacts on the Tortoise.

Good Luck, Ed

11

No. But each toggle had its own curcuit.