Hello,
I am boggled at this one, I just set the car on my track on my layout and it blows my track power fuse. I checked all the wiring in the trucks and the car and did not anything out of the ordinary. No lights light up at all in the car also. So weird.
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If you have an ohmmeter, check for continuity between the pickup rollers and the frame. Look for bare wire on the roller wire.
I don’t have a meter but I did check for exposed wires and did not see any.
I would check the contact in the light bulb socket too.
See if the uncoupler plate is sagging and hitting the center rail. That's has happened to some of my cars.
You can look at the bottom of both trucks for signs of arcing or burn marks.
It's also possible that one or more of the axles are loose in the side frame, allowing things like the coupler thumbtack or the uncoupler plate to hit the center rail.
And buy a cheap meter. the ones that go for ten dollars or so are fine tor train work.
What item number? What Manufacturer? Helps diagnose when you know the product.
I will check those items also, it is a MTH Texas special premier obersation car. I checked all the wires and did not see anything broken or rubbing. I will get the item number
The set number is Mth 20-65228 . I just swapped it with another passenger car base and it works fine. So then I put just the base with the trucks on the track and the fuse blew. So it seems it is something with the base and or trucks. I don’t se anything wrong with the wires. Please see pictures
Has this car been working OK and then suddenly failed? If so, look to see if any wires are chafed or abraded.
Or... has it never worked since you have had the car? If the latter, it could be mis-wired from the factory.
You should buy one of these. Very helpful in sorting out electrical things.
The car never worked so maybe mid wired. Would you know how it should be wired? Please and thank you!!
I will also pick one of those up just added it to my cart!! Thank you
Follow the wires (closely, because they're all black), from the mini circuit board. The pickup wires should both go to the same pad. Good job on narrowing it down to the base.
Take each truck off and see if it still shorts out.
Can I just disconnect the wires from one truck at a time?
If they are wired wrong , how would are they supposed to be wired? Seems like a stupid question but I just wanted to make sure.
@chefmarkt69 posted:If they are wired wrong , how would are they supposed to be wired? Seems like a stupid question but I just wanted to make sure.
Both center pickup wires go to one terminal on the little PC board.
Both truck frame wires go to the other terminal on the little PC board.
The center pickup wires do NOT touch the side frame wires.
You can remove the little PC board from the frame, flip it over and check/follow the wires.
I find I like old fashioned analog multi meters for continuity checks. Spotting movement of the needle is quick and easy. I have 3 digital meters, but still use my old analog most of the time. Either type can be had for less than $10. Analog: Gardner Bender GMT-312 on Amazon for just south of $10.
Could the plugs on that board be reversed? Should I unplug them and reverse them?
As long as the wires are paired correctly, reversing them should not make a difference.
can that little circuit board be bad? If so can you still buy them? It looks to be Al one piece with the wires. Also some of the wires have been flattened. Would that cause this?
@chefmarkt69 posted:can that little circuit board be bad? If so can you still buy them? It looks to be Al one piece with the wires. Also some of the wires have been flattened. Would that cause this?
Set the good base next to the bad base ...........make a careful comparison of wire routing or anything that is different between the two bases. Good luck.
What has happened with this?
Has the problem been solved?
@RoyBoy posted:What has happened with this?
Has the problem been solved?
Yup Chefmark.......any success to report ? 🤔
No luck I have traced the wires and in some areas they are flat not sure if that is a problem. I checked everything over and over. Could it be a bad board that the wires are soldered to? Does anyone have or know if I can buy the wire setup? It is still blowing my main fuse for track power.
The bases looked the same also
@chefmarkt69 posted:No luck I have traced the wires and in some areas they are flat not sure if that is a problem. I checked everything over and over. Could it be a bad board that the wires are soldered to? Does anyone have or know if I can buy the wire setup? It is still blowing my main fuse for track power.
Isn't that just a pad? The board is in the car IIRC.
Have you removed one of the trucks to verify if the short remains? Mark the wire ends with tape before you remove them to make sure it isn't miswired.
It's only 4 wires correct? 2 from the pickup rollers to one side of the pad and two wires to the side frames to complete the circuit. Would have been better if MTH used red and black wires rather than all black, sadly they didn't.
@chefmarkt69 posted:No luck I have traced the wires and in some areas they are flat not sure if that is a problem. I checked everything over and over. Could it be a bad board that the wires are soldered to? Does anyone have or know if I can buy the wire setup? It is still blowing my main fuse for track power.
1. Based on the set number you have given, 20-65228, this appears to be a car with overhead incandescent lighting - correct? It dates from 2013, which I think is slightly before MTH started using LEDs in passenger cars. That helps to trace where I think your problem might be, which is in the power supply to the lighting or the connection between that and the lighting itself, although it might also be something as simple as a burned out bulb on an incandescent lighting board, depending on exactly how the lights were wired. Another simple possibility is a bad on/off switch if this car has one, which I can’t determine from the set number.
2. Anyway, I have stared at your photo of what I think is the light power supply board, which I have homed in on in this image:
3. This does not look like any other MTH light board I have seen, and the part number “MD401 ROHS” printed on it does not register with me - although I have had K-Line PCBs numbered similarly. The three things that jumped out at me are:
(1) On the left side there’s solder blob bridging what seem to be two wire connections, but that may be deliberate.
(2) Below that there are what look like two contact pads - does the connection to the lights themselves rest on this?
(3) What this is attached to appears to be a plastic part that is attached to the frame rather than the frame itself, and maybe it is actually one side of the interior floor. If the frame is metal, which is what I’d expect, is that board insulated from it?
I am not sure but if there are no other components, like diodes, this board looks like it is meant to feed AC power to incandescent lights.
You said "traced". Did you finally acquire a simple continuity tester - either digital or analog? If not, how did you "trace" the wires? Just asking.
@BobbyD posted:Isn't that just a pad? The board is in the car IIRC.
Have you removed one of the trucks to verify if the short remains? Mark the wire ends with tape before you remove them to make sure it isn't miswired.
It's only 4 wires correct? 2 from the pickup rollers to one side of the pad and two wires to the side frames to complete the circuit. Would have been better if MTH used red and black wires rather than all black, sadly they didn't.
Yes it has four black wires, I did remove one of the trucks and yes the short does remain.
@modeltrainsparts posted:You said "traced". Did you finally acquire a simple continuity tester - either digital or analog? If not, how did you "trace" the wires? Just asking.
Yes I borrowed one from a gentleman at work and I even had him look at it. He knows quite a bit about electrical wires. No luck. He thinks it is in the board.
@Hancock52 posted:1. Based on the set number you have given, 20-65228, this appears to be a car with overhead incandescent lighting - correct? It dates from 2013, which I think is slightly before MTH started using LEDs in passenger cars. That helps to trace where I think your problem might be, which is in the power supply to the lighting or the connection between that and the lighting itself, although it might also be something as simple as a burned out bulb on an incandescent lighting board, depending on exactly how the lights were wired. Another simple possibility is a bad on/off switch if this car has one, which I can’t determine from the set number.
2. Anyway, I have stared at your photo of what I think is the light power supply board, which I have homed in on in this image:
3. This does not look like any other MTH light board I have seen, and the part number “MD401 ROHS” printed on it does not register with me - although I have had K-Line PCBs numbered similarly. The three things that jumped out at me are:
(1) On the left side there’s solder blob bridging what seem to be two wire connections, but that may be deliberate.
(2) Below that there are what look like two contact pads - does the connection to the lights themselves rest on this?
(3) What this is attached to appears to be a plastic part that is attached to the frame rather than the frame itself, and maybe it is actually one side of the interior floor. If the frame is metal, which is what I’d expect, is that board insulated from it?
I am not sure but if there are no other components, like diodes, this board looks like it is meant to feed AC power to incandescent lights.
Yes it is incandescent lights, the lights all work. All of those wires are soldered to the back of that circuit board. It doesn’t have an on off switch. Yes there are two springs that rest on that circuit board. That board is secured with those two black screws to the plastic floor. I hope I answered all of your questions.
@chefmarkt69 posted:Yes it is incandescent lights, the lights all work. All of those wires are soldered to the back of that circuit board. It doesn’t have an on off switch. Yes there are two springs that rest on that circuit board. That board is secured with those two black screws to the plastic floor. I hope I answered all of your questions.
Yes, thank you. I have looked at one of my MTH passenger cars of similar vintage, and was reminded that the ground wire runs directly under the center rail roller, which is a potential source of trouble if that wire gets frayed/crimped or the roller makes contact with the truck. The roller is meant to travel straight up and down but almost inevitably it can press on the ground wire. Also if the base of the roller assembly is not fully and properly insulated it can contact the truck with the same result.
I think that it's possible your trouble isn't the board but that you are getting a short to the frame/chassis somewhere around these connections.
@chefmarkt69 posted:Yes it has four black wires, I did remove one of the trucks and yes the short does remain.
Did you attempt it reinstalling that truck and removing the other truck? If it still remains then place just both trucks on the track? This is really a pretty simple deal, it's just 4 wires. Group the 2 wires from each side of the pad and check for continuity between them?
@Hancock52 posted:2. Anyway, I have stared at your photo of what I think is the light power supply board, which I have homed in on in this image:
3. This does not look like any other MTH light board I have seen, and the part number “MD401 ROHS” printed on it does not register with me - although I have had K-Line PCBs numbered similarly.
That "board" is just working as a pad for the springs in the body to touch rather than a connector. Nothing to do with the lights at all. Here is an older car where they did use red and black.
@chefmarkt69 posted:Yes it has four black wires, I did remove one of the trucks and yes the short does remain.
By "remove one of the trucks" does that mean remove mechanically by unscrewing from the chassis...or remove electrically by disconnecting the two black wires from the circuit board?
It appears you can remove the truck electrically from the circuit board by unscrewing the ring-eyelet connector (yellow) and pulling off the press-on tab connector (red). Should not have to cut wires or solder.
This is just continuing the process of elimination. Some temporary tape or the like on track would allow you to apply power to one truck at a time while its center-roller is in compression.
@stan2004 posted:By "remove one of the trucks" does that mean remove mechanically by unscrewing from the chassis...or remove electrically by disconnecting the two black wires from the circuit board?
It appears you can remove the truck electrically from the circuit board by unscrewing the ring-eyelet connector (yellow) and pulling off the press-on tab connector (red). Should not have to cut wires or solder.
This is just continuing the process of elimination. Some temporary tape or the like on track would allow you to apply power to one truck at a time while its center-roller is in compression.
I will give it a try when I get home, thank you very much!!
@stan2004 posted:
It appears you can remove the truck electrically from the circuit board by unscrewing the ring-eyelet connector (yellow) and pulling off the press-on tab connector (red). Should not have to cut wires or solder.
This is just continuing the process of elimination. Some temporary tape or the like on track would allow you to apply power to one truck at a time while its center-roller is in compression.
Like this a lot Stan. 
I was trying to figure out how to get this across to Chefmark .......you did a nice job.
@BobbyD posted:That "board" is just working as a pad for the springs in the body to touch rather than a connector. Nothing to do with the lights at all. Here is an older car where they did use red and black.
BobbyD 's photo with the wiring organization looks good the way it seperates how the wiring is connected to the contact board.
@Hancock52 posted:Anyway, I have stared at your photo of what I think is the light power supply board, which I have homed in on in this image:
3. This does not look like any other MTH light board I have seen, and the part number “MD401 ROHS” printed on it does not register with me - although I have had K-Line PCBs numbered similarly.
It would be good to see this board from the bottom side. Unlike Bobby's photo ,these wires are all crammed in one side possibly leading to some errant contact. 🤔
I agree with Dallas. Those screws are really close to the solder on the side we can see.
@Dallas Joseph posted:It would be good to see this board from the bottom side. Unlike Bobby's photo ,these wires are all crammed in one side possibly leading to some errant contact. 🤔
OK, I have taken apart the car I have with what I thought was similar wiring, and in fact this wiring turns out to be identical to the OP's car.
Here is the bottom side of the contact board:
You will notice from this that the insulation of one wire of one pair is slightly abraded and runs right over one of the other pair. If the insulation was broken on both there would be potential for a short, but I'm not sure that's the OP's problem - unless he finds that the bare wires are actually touching.
Here's a photo of this contact board in place and the spring contacts in the body shell they feed track power to:
All the parts around these are plastic and as there's no metal frame I can't see that the screws holding the parts in place would cause a short. BTW, I think that an earlier poster did not mean to say that the wired board has nothing to do with the lighting - it's the power connection from wheels/center roller to the lights. The lights themselves are mounted on the inside of the car's roof and are 5 incandescent bulbs, and everything around them is plastic:
This is the truck with what I think are standard MTH track power connections of the time (c. 2012/13). As I said in an earlier post, the ground wire from the wheels is run directly under the vertical center roller:
I think that the OP's problem is probably a short somewhere in this assembly - maybe the ground wire has been abraded and is touching the roller when it contacts the center rail or the roller mechanism is not properly insulated from the rest of the truck.
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