No smoke from MTH 20-3776-1

Possible causes are: bad fan motor, stuck impeller, broken wire on smoke motor., or possibly a board problem. You’ll need to pull the shell to investigate…..smoke unit is boiler mounted, so not hard to get at…..

Pat

Thanks,  Is there a procedure on how to pull the shell ?

I also noticed that while engine is running the amber lights on the outside of the lighted 4014 on top of the boiler are flashing, (not sure if that's diagnostic indicator)

@Doug Bo posted:

I also noticed that while engine is running the amber lights on the outside of the lighted 4014 on top of the boiler are flashing, (not sure if that's diagnostic indicator)

That’s not a diagnostic indicator, that’s the 5V being lugged down by increased load. More than likely smoke motor related……

Pat

I managed to get shell off and smoke unit out of boiler. I ohmed out blower motor and it showed resistance. I hooked up a 1.5 volt battery to it and it spun. I'm beginning to think it's not getting voltage to spin. Would that be the circuit board it's plugged into has an issue? If so how do you get a part number for it?   ( I checked MTH's web site and that's not easy to find) Any help would be appreciated.

Did some one plug smoke fan into the wrong connector plug?  Is the solder joint at molex plug good (under heatshrink).  G

The shell has never been off engine until now so the plug is in its original connector (red) As far as the solder joint, you can't see it since there's another board on the underside (both boards are meshed together-probably to save space) I was looking on MTH's web site and I think the board is a boiler board( AE000E32) but is shown as 2 separate boards, the one in my engine is one board( one meshed to the other)

The unit has Whistle steam and normal smoke.  The smoke unit """""normally""""" has a red plug to the heat element, and a green plug to the smoke fan.  The Markers on white or yellow plug.  Again may not be case depending on how they assembled the wire harness.

Are the markers flashing or flickering?  Big difference.

As far as boards can either have a single boiler board for both smoke units, or they use a second longer board for the whistle steam.  There are no meshed boards like PS-32.  They may be co located on a bracket, but clearly 2 separate boards.

The 2020 units seem to be notorious for poorly assembled wiring harnesses.

A Slight tug on the wires to the molex plug that goes to smoke fan may result in a wire coming out of heat shrink due to poor or broken solder joint.  If smoke fluid over filled the smoke fan may be saturated and failed.

I would thoroughly examine harness and plugs first.  Before I buy a new board.  G

Markers are flickering. There is a longer board for whistle smoke, but only 1 boiler board (see attached

Did you check wires?  A tech can test your boiler board for smoke operation.  If smoke off does flickering go away?  This seems to be common especially at lower track voltage for some of the later PS-3 steam.  N&W J from same year as example.  Does whistle smoke work?

It is either board or wiring to smoke unit or smoke fan motor (though you said it ran at low voltage).  That is the AE-1000E32 boiler board.  G

After putting everything back together (and I had to remove it from it from DCS and rediscover it) , it seems like everything is working. Only issue is the engine runs sluggish at slow speeds. I need to reopen the shell to make sure no wires are dragging against flywheel -(not much room in there) I'll run it for few days to see if its ok. I keep you posted.

Thanks for everyone's input

     Doug Bo