I appeal to everyone’s greater knowledge than mine of electronics and, specifically, PS3 lighting.
This is a brand new MTH Amtrak ES44AC #2019. Out of the box I thought everything worked but I failed to notice that one of the ditch lights would not come on or flash.
Once I spotted this, feature and factory resets made no difference. Digging around first on the internet for guidance, I found a YouTube video that describes a problem with the spring contacts to MTH ditch lights – as in they don’t reliably make contact with the pads that supply the power and need to be seated carefully. Off came the shell in the hope that this was a simple solution. No such luck, unfortunately; there is something else wrong.
Here are contacts and the pads they should touch in the center of the photo:
The negative pad is the one towards the front of the engine and the positive pads the two at the rear. I’ll refer to what this picture shows again below.
I first tested the LEDs by putting a depleted 9-volt battery to the respective pairs of springs. This lit the functioning LED but not the other one. On extracting the non-functioning LED from the ditch light housing, it appeared to be cracked at the base. Anyway, it would not light, I pronounced it dead and substituted an Evan Designs 3 mm LED rated for 5-13 VDC. That lit when the battery power was applied, although the color and brightness are not the same as the stock MTH LED. That much I could live with if this feature otherwise worked; I can't track down a stock MTH ditch light LED.
However, on reassembling the engine so the LEDs were powered from the pads, the non-functioning LED still did not work while the other one did. Before this, I had tested the power supply with a multimeter while the shell-less engine was on rollers and set to forward at about 15 scale MPH. If I am reading my multimeter right in terms of decimal point placement, it showed .687 VDC to the pads feeding the functioning LED and .527 VDC to those feeding the non-functioning LED. I didn’t think that difference was critical although it did seem odd.
Taking the shell off again, I did two things. First, I checked the DC current to the sets of pads; the functioning one read 8.73mA while the non-functioning one read .000mA. There was no load, as in the LEDs attached to the pads, when I did this. Second, I tried manually holding the spring contact assembly in place on the pads while the engine was powered on rollers going forward. This showed that the non-functioning LED did in fact light but extremely dimly. So, I deduce that there is some power getting to it but even using a 3 volt LED, the pads for the non-functioning side won’t light it. (The other pads light it up like a torch and I have only tested it on them for a second so nothing goes up in smoke.)
I have also taken AC voltage and current readings on the pads but won’t repeat them here unless somebody tells me they could be relevant.
The anode pad to the non-functioning LED (at the back of the board) is fed by a brown wire, which I understand from the PS3 upgrade diagram posted elsewhere on the Forum connects to pin 5 on the PS3 board. However, this bit of knowledge does me no good as I have no idea what might be wrong or how to remedy it. I have wondered about re-installing the sound/chain files on this engine but can’t do that this side of Christmas.
Anyone have an idea what’s going on with this engine? In case it matters, I have a revision L TIU that is no more than a year old and the remote shows DCS v. 4.20.
