I've got 11 Athearn Genesis locos with Factory fitted Tsunami or Tsunami 2 decoders and have started replacing the horrible Athearn bulbs with LEDs. I've just completed the first upgrade, CN Ex Demo SD70ACe #8103, and couldn't understand why the LEDs weren't working after I'd soldered them to the pads. I unsoldered them and tested them again using first a 3v camera battery, then a 9V and finally hooked up to the track power - and they worked perfectly. Although there may be no difference between the Factory Installed decoders and the Retail versions as far as functions and sound files are concerned, there are physical differences - in this case, the Athearn boards only have the Common terminals V+ and not V+ and V1 as per the Retail boards. On the Retail board, V+ is rated at track voltage and V1 is rated at 1.5v for incandescent bulbs. On the Athearn board, V+ is only rated at 1.5v So, if you are installing LEDs, you'll need to wire the LED commons leads to the Track Pickup pads. I've now wired the front headlights and ditchlights Common lead to the Front Right Track Pickup, and the rear headlights to the Rear Left Track Pickup, and I am very happy with the results. The next locos I'll be doing, as soon as the Kit arrives, are a CN SD70i and a CN SD75i, which also have Tsunami 2 and the added challenge of also having working rear ditchlights.
Wiring directly to one track pickup results in the LED being turned on and off multiple times per second (as the DCC square wave alternates). You may want to consider adding a positive halfway bridge rectifier, which locks the positive voltage from each pickup, providing a constant voltage. For example, p/n DA3X103E0LCT-ND at DigiKey
Nice work! What LEDs did you use for the upgrades? I'd like to update some of my locomotives in the future.
I'm using "MONSTER LEDs by Big Al Mayo" which I bought from him via that well known auction site. This is the kit I purchased: - https://www.ebay.co.uk/itm/HO-WARM-...524102&hash=item2ac7eab743:g:DxwAAOSwdGFYvjK8
OK, thanks that Rick. Just found out DigiKey are also in the UK so I'll be placing an order 7 of them. I have 2x CN GP38-2Ws and 2x CN GP40-2Ws with factory fitted Tsunami as well as the 3 locos mentioned above. I've already purchased retail Tsunami 2 boards for the final 4 locos, an IC SD70 "Deathstar" and 3x CN SD70M-2, to replace their factory fitted Tsunami.
I'm going from memory from working on other Genesis, bulb to LED conversion. Put the loco on the track, turn on headlight, F0F. Measure voltage from the end tab labeled "Headlight" in your photo, to the solder pad I have drawn a blue line to. That should measure 13.5 volts or so, with the Headlight tab being negative, and the solder pad I have pointed to being positive. If this is correct, that is where you connect the common (anode or +) leads from your LEDs. The function leads from your LEDs will require a resistor. I would use 1k ohm 1/4 watt minimum resistors. But you can use 2k or 2.2k with very little loss of light, greatly reduced current to the LED, and greatly increased longevity of the LED.
