Lionel Vision Line Genset Won't Move - Solved

you may have damaged some components on some of the boards or drive board, I would try a total reset, if that don't work you probably damaged a module which is why it is not working  again!

This doesn't appear to be a diagram of the 6-28323 Vision Line Genset.  First off, the VL model has three smoke units.  Next, it only has one drive motor.  This appears to be the GE ES44AC, look at the title block.

GRJ, you are correct that the schematic is ES44AC but every connector is lining up pin for pin. You can see the diagram has the connections for extra smoke units.  

Trust me we can use this schematic with confidence.   Now just looking for what to start pinning out and what to look for.   

Well there is also a fan control board which is not on that schematic...how that affects your sorting it out, I can't say.

Actually, it is on the schematic Chuck, just with a different number.  I'm assuming that's because it's only controlling one smoke unit and not three of them.

In any case, lack of movement is unlikely to be associated with the smoke unit, I'd be looking at the DCDS and it's connection to the the system.  There's only a handful of signals going to the DCDS, that's where I'd be looking first.

The cab is removed so the harness between the chassis and the that smoke control board is disconnected.   Also, the light harness is disconnected which only keeps the ground lights in play.   

I really would like the focus on what is preventing movement.   Where should I be measuring to support/refute the motherboard and DCDS.   I can eventually swap those components between the Up and NS but that’s a lot of work.  I really want to find with my meter.

I'd be tracing all the wires from the DCDS to their destinations.  Top suspects would be is serial data getting from the RCDR to the DCDS.  You'll notice that the serial data goes from the RCDR to the RS 6 motherboard, and is then forwarded to the DCDS on pin-1 of J2.  It also goes to the IR LCS board and the headlight board.  I have no idea if the RS 6 MB is buffering those signals, but I suspect due to the distribution that they probably had to boost them on that board.

Of course, the other place to look is the actual motor connections, if one of those is bad, clearly the motors won't be running.

I need to come up the learning curve some.  Is there any voltage to measure on serial or is it just pulsing 1s and 0s?   What is difference between Serial and RSSerial on the diagram.  What is CAM circuit and its function and voltage? Should I only measure 5VDC pins to the associate ground (GND) terminal?

RS Serial is apparently repeated, and may have either information stripped out or added.  It's interesting to note it goes to the track LCS transmitter.  CAM is a generated pulse that tells the RCDR that the locomotive is moving, it's like the wheel cam on old TMCC locomotives.  Serial data is constantly changing, the only way to really view it is with a 'scope.  I would only measure the 5V to the matching ground as not all grounds are created equal.  I suspect many are, but I don't know for sure.

I think we got this Genset figured out.  After a few hours of poking and prodding I eventually swapped motherboards between the inop NS over to the UP.  That wasn't the problem.  So just as I was getting ready to swap the DCDS boards I was starting to disconnect the harnesses and noticed there is one connector that has a 3 legged triac looking thing soldered to it (see schematic below and pic) .  GRJ later corrected me that is actually a Voltage Detector.  Well when I swapped this little doodad between locos the NS started moving.  Not sure where to find a replacement (Lionel DCDS parts photo does not show it) but currently looking at some electronics suppliers.

BTW, the schematic link above for ES44AC does show a 691MB14A01 motherboard.  These Genset actually use 691MB14A00 but that didn't impact or ability to troubleshoot.

Big thanks to GRJ for his coaching and advice to find the problem. 

At Digikey

https://www.digikey.com/produc...ge=1&pageSize=25

Yep Chuck, we found them at Digikey, he's already got them ordered.

I ordered replacement Voltage Detectors from Digi-key and it fixed the problem.  It was a tad challenging to solder into the connector but I eventually got it to take.  Cost was $0.70 each but they are being discontinued.   

Digi-key Part No: 1662-1827-ND

MFG: Ablic USA Inc.

MFG Part No: S-8093CLY-B2-U