I have a set of Proto 2000 FA1's with TCS DP2X-UK decoders installed and factory headlight bulbs. I thought I could just remove the bulbs and install LED's with 820 ohm resistors on the factory board pads (just like the bulbs). For some reason, I get nothing out of the LED's.
I know the pads are getting 1.53 VDC when the headlight output is on, but still nothing out of the LED's. I've doubled checked everything with a meter and verified correct LED polarity and still nothing.
What am I missing here? Has anyone added LED's to this configuration? I'd rather not replace the factory board and TCS decoder at this time since they work just fine.
Jeff
Swap the leads?
Jeff,
If the pads are getting 1.5V, you don't need resistors. Or, was your measurement taken through the resistor? Did you also double-check the LEDs with a battery to make sure it's functioning?
Lastly, try rotating the DP2X decoder 180 degrees...
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
White LEDs usually require around 3 volts.
Ah, forgot about needing 3VDC.
I know the LED is good and wired correctly. Since I'm only getting a little more than 1.5 VDC, I wonder if there's something happening on the factory board to limit the voltage being outputed by the decoder for bulbs?
If you're using the original lighting board, which I assume you are based on the decoder you have, you'll only be getting 1.5 volts. Most LEDs need at least 3 volts. I just did a conversion on the same FA unit and used TCS's motherboard which already has the resistors installed for LEDs. With the original lighting board I believe your stuck with incandescent bulbs.
LNE404Since I'm only getting a little more than 1.5 VDC, I wonder if there's something happening on the factory board to limit the voltage being outputed by the decoder for bulbs?
It's likely the original incandescent lighting that came with your FA were only 1.5V rather than 12V bulbs.
I would remove the factory lighting board and just hardwire in your DP2X decoder. You'll then need the resistors so as not to blow the LEDs.
A TCS harness with an NMRA socket at one end and bare wires at the other end would be the easiest approach. Just be sure to secure the harness with Kapton tape so that the decoder doesn't inadvertently short to the chassis.
Yes, I'm using the factory board since the DP2X-UK decoder just plugs into it. Here's the link to the TCS installation site to see what I'm doing.
https://drupal.tcsdcc.com/installation/ho-scale/1395
It's a simple plug-n-play install, it's a shame to replace the board. I'm going to do some further digging, otherwise; it's a new board and decoder.
If you are adverse to soldering then a new board is your next step. If you're not adverse, soldering in a harness with an NMRA socket to plug in your DP2X would be a less expensive alterative than a new board.
FWIW,