ps3 light problem

I was trying to find a parts breakdown to verify how the ditch lights are connected in this engine.

I have seen 2 different ways this can fail and give you the intermittent problem you have seen.

The one way is then they use the spring loaded contact method in the shell to mate to a PCB contact pad mounted against the stamped metal frame. This is intermittent because over time or with a cracked body post, the spring contacts flex up away and fail to make contact.

But, some other engines are hard wired with plugs on the engine shell side and a PCB with mating color coded sockets mounted to the stamped frame. This is a single sided traces PCB and force on the connectors can crack and rip the solder pad and trace making the LED intermittent.

Either is possible to fix, but you have to remove the shell and inspect to find what method and what possible fault. Also, I used a CR2032 coil cell battery to check the LEDs. Since the coin cell battery has internal resistance, it can power an LED for testing with no resistors and not damage them so for PS3 based engine, I find this ideal.

Again, I have seen both errors now a few times, even on brand new equipment.

Example with spring style contact pad system.

https://ogrforum.com/...c/119400164584420318

2019_Ditch_Lights.jpg

Here is the lighting distribution PCB style many engines use. This is where I've seen bad or broken solder joints from the wires and connectors flexing and ripping the relatively thin traces. The Ditch lights are 2 of the red connectors.

Closer picture of board as installed- again noting that 2 of the 3 Red connectors are the ditch lights.

The backside of that PCB after the center mounting screw and short plastic standoff are removed.

Again, the failure I have seen, the thin copper trace on this single sided copper PCB can rip or crack if force pushes on the pins of the sockets pretty much in any direction. That will then cause either an intermittent connection or complete open circuit of an LED output. I've had to use wires to rebuild traces on my fair share of this specific PCB.

And yes, I'm showing a Railking engine, so because we do not have a parts diagram specific to your engine, I believe the wiring is highly likely to be one of these 2 methods MTH used- either the spring and PCB contact pad system- and tons of ways that can be intermittent with the shell and body post mount flexing, but then also, the PCB distro board, I've also seen them be intermittent or just outright fail open circuit. Your system could have one or both types of connections. I've seen different variations. I don't happen to own a Premier SD 90

@Hoosier Rail posted:

where things get really weird is that i took this engine to an authorized MTH repair shop. they put it on their test track and the light worked immediately and for several minutes with no modifications or programming/resets done whatsoever. they were using a z4000 in conventional as well. I took it home. does not work again. what could be going on here?

thanks

Again, that is not weird at all. It's a basic understanding of how these locomotives and wiring harnesses are built and the contact system to the shell since it can and does has to be removed for maintenance and repairs. In some ways, the spring system is great to a tech or you working on your engine- no wires to worry about unplugging. The downside is yes, it's not a perfect system and yes intermittent connections can happen. It's kinda unfair to blame the tech when you brought an engine and just from transport it flexed enough to make reliable contact when they tried to reproduce your issue it worked in front of them. He's not getting paid to take apart engines for fun so it if worked no reason to pull the shell and do some type of deep dive on a problem that for all purposes- it worked for them. Again, per your story, it sounds like you took it to a shop, it worked fine there, they did not do any work and you took the engine home. Then at home, and somehow handling, lifting in and out of the box, placing on the track- likely the connection became open circuit and the one ditch light fails to operate.

This is not a board or programming issue. This is simply basic wiring and connector systems and their downfalls.

Also, this is a used 2013 engine going on 9 years old. Entirely possible the engine was opened and serviced at some point meaning a body post with the spring contact style system could crack or flex, the screws mounting the body might not be fully tight, or in the case of the distro PCB, when someone unplugged and plugged the connectors during a service, that force on the connector pins cracked a solder joint that then became intermittent.

From the manual, the body mount screw locations https://mthtrains.com/sites/de...ction/20dl10549i.pdf

Again, sorry, I wish I had your specific engine or a breakdown to validate which style of connection that engine used.

Picture by user @Hancock52

thank you very much for the detailed response. i will be looking into this. also wasn't blaming the tech at the store. it makes no sense to open it up when its working fine. i just went home assuming it was something with my setup and happy that it appeared the engine was fine.

Sorry, I realize my reply could be taken the wrong way. I don't think you meant to blame anyone, you just didn't understand the technical details.

#1 I don't think it has anything to do with your home setup.

#2 The assumption the engine was fine- that's a long and slippery slope. I mean yes, great, the ditch lights worked and thus highly likely nothing is wrong with the expensive and hard to get PS3 control board. Again, the fact it did work recently and likely no indication that something damaged the output of the board is a good thing.  Sadly no, the problem came back which IMO comes back to known possible problematic connections between the board and the actual ditch LED. Without you or a tech opening the engine and thus you knowing or having an idea of how this specific  engine connects the LEDs in the shell to the PS3 wiring harness and PS3 board, I tried to give you both scenarios that explain your intermittent failure (works sometimes- like at the store in front of a tech, but yet at home does not work).

#3 The fix could be as simple as loosening the body post mounting screws, lifting and wiggling and reseating the shell, then tightening the screws and the ditch light suddenly works. Or it might take a service tech visit, deep inspection of the wiring system, possible replacement or repair of whatever the fault is. Could be a cracked body post, could be one of the contact springs, could just be the smallest misalignment of the body and contacts relative to the frame, could be something in between the contact like a wire when the shell was assembled. It could be a pinched wire, a cracked solder joint, an unseated connector, heck, even the micro ditch LED and mounting PCB could be intermittent.

I tried to give some high level pointers on testing of how I would approach the problem (CR2032 coin battery testing) but it sounds like you did not and generally do not open or work on your engines (sorry if I got that wrong, just how I read your reply).

I think it needs another service tech visit and this time around the shell removed and more in depth look at why it might be acting intermittently. Hopefully, they can bring you resolution.

I jut recently went through a thorough inspection and tune up on a used PS2 engine that someone likely ran into a similar intermittent problem. They ditched the spring contact system and used connectors to bypass and correct the problem. It wasn't as clean and pretty of a solution, but I could just imagine the user's frustration that put them down the path of desperation for a solution.

Hoping you don't have to go that route, but sometimes that's just where the repair path can go.

you are correct, i do not generally open these things up an mess with them. i have done a smoke unit wick replacement but getting into electronics with my limited knowledge on their workings worries me with such expensive items as these engines and their components. the tech seemed extremely knowledgeable. i will try loosening the body and moving things around but beyond that probably will take it back, as you say, for a deeper inspection with the shell off and maybe showing him your ideas on it.

vernon, turns out you were on the right track so-to-speak. it did have to do with the tightness of the body screws in a way. this sprung part provides power to the ditch lights and simply wasn't making good contact. if i pressed on the shell it worked. so i just added some electrical tape to the post this piece mounts on to increase pressure on the springs. works great now. thanks for the input!

Typically what I do when the springs aren't making contact is to stretch the springs a bit, they compress with age.

You may want to try cleaning the springs as well if you are buying the engine second-hand. When I had an engine shell repainted by someone else, one of the ditch lights stopped flashing.  Since there was some evidence that there was some primer paint on the inside of the shell, I used a q-tip with some alcohol and cleaned off the springs.  That in combination to the recommendation by Gunrunnerjohn of stretching the spring did the trick.  When I reattached she shell, the ditch light worked again.

-Ed Abbot