i have just installed a Tsunami TSU-PNP Alco diesel sound decoder. It all works very well apart from the lights. I cut the -ve leg on each led and wired back to the board. I also commoned the +ve side of the leds. I parallel the number board lights and I parallel the two headlights. I have installed 1000ohm resistors in each led circuit. The headlights are wired to the headlight tab at the head of the board and the other circuits are wired to the function tabs at the side. One of the headlights did go on forward motion for a short time but then stopped. I am not sure what voltage comes out of the tabs. Any comments greatly appreciated. cheers
All the SoundTraxx lightboard decoders I have installed have twelve volt outputs and five volt outputs. That was maybe ten years ago.
Shrink wrapped, only twelve volt outputs as I recall.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
The manual shows 1000 ohm resistors on all the negative side of all LEDs
https://www.soundtraxx.com/manuals/Installation-Guide.pdf
Henry
COB Potomac & Northern
Shenandoah Valley
Yes, that is correct. Resistors to -ve with the +ve commoner. That’s what I have done, cheers P
It sounds like the one that lit briefly burned out. Unusual if wired correctly.
Did you test the led's prior to installation? Not mentioning any names but I know someone who connected the led + to the negative wire. They don't light at all that way.
You could also measure resistance on an uninstalled resistor, although nobody has complained about fake resistors lately.
No idea of your expereince but you cannot test an LED with an ohm meter. I use a 9 volt battery and a 1k resistor..
richg1998No idea of your expereince but you cannot test an LED with an ohm meter. I use a 9 volt battery and a 1k resistor..
I suggested measuring the resistor, not the led. My assumption being, if they came from Ebay and China, they might not have the best quality control.
They'd have to be REALLY bad resistors - the thing about a 1K as normally recommended is that you can go to half that and still not exceed the LED current limit, and more than double that would still allow the LED to light up.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Admittedly I was grasping at straws, because if the OP wired as he said, there should be light.
There should - but I suspect maybe a missed connection. The MTH geniuses used a negative common for their LED boards, and to use the same small PCB to hold the LEDs, traces need to be cut - FULLY. There was a Yahoo group with step by step install instructions that included conversion of at least one MTH loco and shows exactly what needs to be done to the factory boards to use a standard DCC decoder.
The Tsunami PNP is a replacement board, like a loksound select direct. The factory board should be gone.
Kind thank you to all for your help and assistance. Much appreciated. Update, ok, so I have now got the number board lights and cab light working and continuing to work. It was an issue with my NCE controller or my accurately my ability to use the NCE procab to access the 10-20 and 20-30 function keys. i have finally got that sorted so that lights connected to the function tabs are working fine. Still an issue with the headlights however.. I will dismantle and see if I can figure what is happening. Yes, I may have cooked them somehow although I did heat shrink all exposed wiring . And yes, orginal MTH board well and truely discarded, never to see the light of day again! Grrrrr!
BigDaddyThe factory board should be gone.
Right, but —
MTH, Athearn and Broadway, among others, use several "sub-boards" which have an array of LEDs and resistors, sometimes diodes and voltage regulators which can easily be snapped in to the chassis and quickly plugged into the main decoder or motherboard at assembly.
IMG_7105_BLI_LED by Edmund, on Flickr
IMG_7832 by Edmund, on Flickr
A couple of the steam locos I've opened up have four or five sub-assembled boards for the smoke unit, headlight, chuff sensor and motor feed. Any one of these can have components that might not play nice with a replacement decoder. You have to "ring-out" each wire on a case-by-case basis.
Above shows one from a Broadway F7.
Cheers, Ed
In the MTH FA3 there are 3 separate pcb’s. The one in the nose of the loco has the 6 leds with “internal” connections back to a soldering strip. There are no resistors or caps etc. the -ve sides of each led are all connected back to one tab on the soldering strip. The other 4 tabs feed +ve to each led. I have had to isolate the -ve leg on each led and wire it back to the decoder - easy enough,just time consuming. The +ve side of each led was able to be commoned at the soldering strip with just one wire going back to the decoder. All the other boards were completely removed. At the end of the day there is only the pick ups front and back, the motor connections and the speaker connections to wire to the tabs on the decoder. The lighting is a separate issue. As I stated earlier, apart from the headlights, the new decoder is working fine with all the functions working perfectly. The sound is so much better than the original MTH sound too.
Porkster Yes, that is correct. Resistors to -ve with the +ve commoner. That’s what I have done, cheers P
Actually, resistors can go on either the common or the negative side of the LED; it doesn't matter. I choose the common (+) side only to be consistent.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.