Well. I have a imperial blue comet that does not smoke..fan motor operates, but nothing is emitting..blowing into it..could the elements Go? Or is it some board issue? I want to test the wires to see if i get anything there.
Thanks
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When the wick gets charred bad enough, you won't get smoke. Was it bought used?
First off, can you feel any heat in the air stream? It's actually pretty hard to get an MTH smoke unit to not emit any smoke, even with a cooked wick.
Did you do a factory reset and start from there? How about adjusting the smoke to maximum output?
gunrunnerjohn posted:First off, can you feel any heat in the air stream? It's actually pretty hard to get an MTH smoke unit to not emit any smoke, even with a cooked wick.
Did you do a factory reset and start from there? How about adjusting the smoke to maximum output?
I'd like to agree with you but actually it's easy. Run the engine continuously without smoke fluid. People do it.
I agree that cooks the smoke unit, but to get absolutely no smoke takes a lot of cooking. 
Not really. I see it a lot too. The wick is so hard and black it does not move fluid even though the bottom of wick is wet.
Measure resistance across element solder pads. Should read 8 ohms. If 16, one element opened. If infinity, both are open.
After that chase wires to board, which means through engine harness and tender harness.
Of course model matter... if 5V and board in engine simpler wiring check since direct connection. IF 3V or 5V in tender the engine PCB, and tether come into play. Could be broken solder joint on engine PCB. G
I had the same problem with one of my steam locos running around my Christmas tree. I thought I had disabled the smoke unit but apparently I hadn’t. When I opened it up, the wick was pretty charred where it contacts the heating resistors. I ended up replacing the wick with tiki torch wick that I cut to the appropriate length. Works like a charm now and only took 15 or 20 minutes.
Ok. First I'll pull the smoke unit apart and see what's up there and then check polarity.. I usually replace the wicks with tiki wick.. fast and good results.. my gear is a board issue though.... thanks all. I'l post what I find
gunrunnerjohn posted:First off, can you feel any heat in the air stream? It's actually pretty hard to get an MTH smoke unit to not emit any smoke, even with a cooked wick.
Did you do a factory reset and start from there? How about adjusting the smoke to maximum output?
John..i did factory reset..nothing..took out bad parts of wick.. still nothing.. max output..nothing.. too bad these engines don't throw a code like a car! Lol..
I'd check the wiring all the way back to the board from the smoke heater, and also check the resistance of the heater, it should be in the 8 ohm range, anything between around 7 to 9 is OK. If all of that is good, the board may have a problem, could be the smoke FET got cooked.
As mentioned, check from the board to the smoke unit. I like to remove engine and tender body and plug the tender into the engine. Go to the 4 pin position on the end of the board and hit each wire one at a time and check for continuity with the smoke heaters and fan motor. If you have no continuity on one or more wires, do the same drill between the 4 pin position and the ten pin connector on the rear of the engine. Find out where continuity goes south and fix the issue.
If you are loosing continuity in this area, here is what you want to look for. With your continuity meter, hit each pin on the ten pin engine connector and look for continuity on the wire pad that goes to that pin. If you see no continuity, look at where the pin comes into the board and you should see a circle that shows lightly around the top of the pin. You now have a cold solder joint that can be fixed with a hot solder iron quickly touching the pin.
One more note. On the top of the smoke PCB usually two wires are attached near the edge of the board. These wires connect to a board trace that goes to the heaters. With your continuity meter hit the incoming wires where they hit the board and then the heater. If you have no continuity, forget the trace and hard wire from point A to point B. This situation is showing up a bit as engines get older. Follow what the guys on the post suggested and use what I posted if nothing else works.
I am big on test equipment and when I hit what you have, I use my test smoke unit with the 4 pin plug. I plug into an operating board and if my unit works, I then do not have to go downstream. If my unit does not work, now I do not have to go crazy testing things and focus on what the board issue may be.
Easy fix and I am sure you will hit it.
That is a mux board for controlling 2 lights circuits across one wire for the engine. The engine also has MUX board in it. The Engine MUX makes PV for heater element. You need to watch smoke unit while powered up if possible. Does the fan turn, does current go up? This could be a bad fan motor, slipping or stuck impeller, bad elements, bad control wires, bad circuit components on board. Wiring on MUX engines is a little more complicated and you need the engine and tender apart when you check wires between board source and smoke unit. G
GGG posted:That is a mux board for controlling 2 lights circuits across one wire for the engine. The engine also has MUX board in it. The Engine MUX makes PV for heater element. You need to watch smoke unit while powered up if possible. Does the fan turn, does current go up? This could be a bad fan motor, slipping or stuck impeller, bad elements, bad control wires, bad circuit components on board. Wiring on MUX engines is a little more complicated and you need the engine and tender apart when you check wires between board source and smoke unit. G
George, the ohms between the heater wires was 8. so that seems good. The fan motor blows air, I can feel that when I power the engine. the lights all work, with led markers and headlight. The cab light and firebox work fine. ill check continuity through the tender to the board, but it seems something is blown.
Because lights work, that means PV is being generated by Engine MUX. Since fan blows and you have LED and I assume speed control that means 5V and fan control are good. Can you read current when you turn smoke on and off? It should jump from about .3amps to .7-1.0amps when smoke turned on. If so the elements are getting current. That would mean wick burned or not between elements. If no current change either there is a break in a wire connection or a bad Heat Element FET on PS-2 board.
To trace continuity, with shells off and engine and tender connected place one probe on brown wire in PS-2 4pin connector and the other on the brown wire solder joint at the smoke unit. Should read 0 ohms. If not walk back test points from smoke unit to engine to find the break. Could be wire break under heat shrink at 2 pin connector, engine PCB solder joint, bad tender tether.
Second is to test the purple wire coming out of the engine mux to the purple on smoke unit. This purple wire will feed smoke element and each bulb. HL, IL. FB bulbs. I have seen broken solder joints under the heat shrink. G
Im' guessing smoke..fet blown...
Chris D posted:Im' guessing smoke..fet blown...
you could unplug the smoke unit and send low DC voltage thru the wires to test the smoke unit. I use a couple of AA batteries in a spare holder. Don't feed the board when connected.
If you are measuring the smoke resistance through the whole path, then it's likely that you have a board issue. Joe has a good idea, I personally use a bench supply at around 5VDC, it also allows me to see the actual current being drawn.
That's better John. I just figured he may not have that set-up.
You're probably right Joe.
gunrunnerjohn posted:If you are measuring the smoke resistance through the whole path, then it's likely that you have a board issue. Joe has a good idea, I personally use a bench supply at around 5VDC, it also allows me to see the actual current being drawn.
john. my volt meter has a power applied selection. not sure volts, minor im sure, but it makes sound when you have current through the wire. pretty neat.
Engineer-Joe posted:Chris D posted:Im' guessing smoke..fet blown...
you could unplug the smoke unit and send low DC voltage thru the wires to test the smoke unit. I use a couple of AA batteries in a spare holder. Don't feed the board when connected.
joe, I never thought of actually putting power to the plug end from the board and powering the actual fan motor and heater. thats a good idea. couple AA batteries in a holder. Nice! thanks for advice!
How about a picture of the voltmeter panel, maybe we can guide you. 
That is not a good idea and plenty of fans run on battery and not on the pulsed power. The motor is simple. Should read 11 to 12 ohms disconnected. If less than 10 and higher than 12 potential motor issue. I do hit them unconnected with 9V battery to just spin them in both directions make sure impeller not slipping and clean the commutator and brushes. I do this before putting new fan motor in a unit.
The heating element is simple resistor. So if the VM reads 8 ohm resistance through the wires at the board connector so it is a full path through the wires; than the elements are good. Same with smoke motor at 11-12ohms.
Why go to all this extra trouble and risk board damage if you forget to unplug the connector. The VM works. No need to prove it with a battery. G
