Repaired Mth 20-20189-1 PS3 F-7 Trailing A unit smoke fan not working.

MTH item number?

20-20189-1

Plug a 6V incandescent bulb into the fan connector and turn on the smoke.  If the light lights, it's something with the motor.

Hi Gun runner John, can you please advise me we’re the connection is ? Also I  don’t believe I have a 6v test bulb set up. I do have a volt meter.

I did connect the motor to an Rc car nickel metal battery pack and it ran great.

There's a green 2-pin connector for the motor usually.  The voltmeter might not give accurate results as the signal to the motor is a PWM signal.

Ok that makes sense, would the connection be in the top of the board? I see a bunch of caps and a large long whit plug with a bunch of wires in it.

Please see pictures

It’s the gray and green wires near the left gray wire nut.  There may be a two-pin  connector under the smoke unit (you may have to unscrew the smoke unit to access it).  If not, you will have to unsolder the wires from the fan motor to do the lamp test, mentioned above (note polarity) as the wires terminate in the 40-pin socket on the board.

It looks like someone did some repairs as the power wires were spliced/insulated due to a short, pinch or rubbing.

I actually removed the motor to inspect and when I went to reinstall I added some wires to make it a little longer for easier access. I soldiered them and put some shrink tube over the wire to seal them.  As for the the positive and negative. Would the grey be the neg and the green wire be the positive? Sorry for all of the questions.

Some of the fan motors have a gray dot on the motor where the gray wires goes.  Otherwise, reattach the wires to the same terminals, otherwise fan will spin backwards.

Yes I understand but can you tell me which wire is positive and which wire is negative? Does the polarity matter when I go to connect the 6v bulb to test? Thank you

No, a bulb, an incandescent bulb with a filament is AC or DC and does not care about polarity.

Ah, got it now it understand, you learn something new everyday!!! Thank you so if the bulb doesn’t light up then what would be the issue?

FAN FET (Field Effect Transistor) blown on the PS3 slave board.I'm hoping it's basically the same part and relative placement as a full blown PS3 board.

https://ogrforum.com/...0#158251952137681860

Being how tiny that surface mount transistor might be, this might be a full board replacement. Ouch $80

https://mthpartsandsales.com/shop/search/results

Keyword search "slave"

Here's the thing though, it stopped working for a reason. Unlike the black box that I find so many people treat electronics like that they do not understand, don't just blame the FET for failing. Something caused it to fail. Either wiring, or a bad motor, jammed impeller, something causing likely high current draw.

You might be at that point where having a tech look at it, properly fix the problem, repair your old board or get a new one, likely replace the fan motor out of caution to protect the new board might be the right answer.

I just would hate to see you buy a board, slap it in, and then smoke it in the first 30 seconds of powerup. Then you both paid for a board, and still had to send off for repair.

Hi Vernon,

yes now that I think back, when I first started the locomotive the smoke unit fan was making a bit of noise. This is an almost brand new unit that the smoke was never used before. So most likely when I started it up and me not knowing what was happening under the hood say. I took it apart and checked the impleller and me thinking that the impeller was loose. I put a drop of glue on it and put it back together . The glue dried and Jamed and in turned burned the board. All of this caused be me and my lack of knowledge. Thank you for the help so much.

Vernon,

if I do replace the board would I have to do anything else besides just remove the old one and plug in the new one? Ex programming of any sort or soldiering anything?

When you order the new board, in the notes for the order put in your product number so they would ensure it was programmed for that engine.

ok that makes sense, then when I get it is it just plug and play?

Should be plug and play. But again, this started because of a smoke motor, you replaced with a new smoke motor and lubed it right?

Otherwise, send this to a tech. I'm trying to help you save money. This could have been as simple as adding a drop of oil early on.  It jumped to glue the impeller, lock the motor, burn the circuit board. Mistakes were made, I'm not trying to give you a hard time, but say let's not make more mistakes and continue the pain and expense to your wallet.

And just because you tested the fan motor with a battery pack-

@chefmarkt69 posted:

I did connect the motor to an Rc car nickel metal battery pack and it ran great.

it might be drawing higher than normal current and just kill a new $80 board.  I personally would not trust the original motor after you told me what you did with the glue.

Smoke fan motors are sold under the common repair parts and upgrades link

https://www.mthpartsandsales.c...ts/240?type=products

Hi Vernon,

yes my thoughts exactly, I have a new motor on order.

@chefmarkt69 posted:

I actually removed the motor to inspect and when I went to reinstall I added some wires to make it a little longer for easier access. I soldiered them and put some shrink tube over the wire to seal them.  As for the the positive and negative. Would the grey be the neg and the green wire be the positive? Sorry for all of the questions.

The gray is positive and the green is negative.

Thank you Gin runner John.

I spoke with MTH parts via email, they said when I get the new board it self learns from the lead locomotive board so no flashing required. I order a new board, fan motor and new impeller. Oh and a new wick might as well do all components in area except the heating element’s. Those are all good. Stay tuned and thank you all for all the help in this matter!!! Now I will have a PS3 board extra but with a bad FET chip on it. No sure what to do with it??

Chefmark,

I just replaced the fan motor in my MTH Y6B last night and I would recommend that you contact MTH parts and add the gasket for the motor to housing and the gasket between the circuit board and the smoke unit itself. Mine tore even using a razor to separate them. At a buck apiece it is worth it.

This one doesn’t have the gasket on it. But thank you for the suggestion it really helps!!

All those smoke units have a gasket, or should have.  I'd add the gasket!

Ok how do I tell which one to get? Thank you for the help!!

it seems the quality control on this unit slipped though the eyes at the factory!!! Lol I wish I could get them to stand behind this locomotive and reimburse me for the parts that it is missing and or defective!!

@chefmarkt69 posted:

Ok how do I tell which one to get? Thank you for the help!!

Found them, they don’t have the five pack they sell them single at $2.00 ea plus $10 shipping.

FYI, I was able to cut a slit in the gasket to get it over the resistors that heat the wick, wish I had taken a pic but I think you will see what you have to do.

When I have to put them over existing resistors, I just cut out the gasket between the resistors and enough room around them to drop them over the resistors.

Just checking before I install the new Slave board and smoke unit motor and wick and gasket. I extended the wires from the old board to the smoke unit. I did use the same size wire, it was just a little short from the factory ones. Will this be ok for the new board? You can see this in a picture above. I do believe that the last board fried because the factory smoke unit motor was bad from the start.

The wire that MTH uses, amazing as it seems, is #28 wire for everything except the motor and the track power.

Hello,

I received the new smoke unit motor today!! Only one thing the old motor had a grey dot on the bottom. I believe to tell you positive pole and negative pole. The new motor doesn’t have any markings on it. Does anyone have an idea what I should do?? Thank you

I soldered short leads to the motor because like you, I found the factory ones awful short, and then tested the motor with 3 volt battery pack and checked rotation. FYI my first guess was right😊

There should be at least a dimple where that gray dot was, connect the gray lead to that pin.