Smoke fixed for used MTH ps2 Mallet

It’s smoky now!!!  Good job!  I had one that the fan wouldn’t turn.  I replaced the fan motor and that was all it took.

@Mark Boyce posted:

It’s smoky now!!!  Good job!  I had one that the fan wouldn’t turn.  I replaced the fan motor and that was all it took.

How did you test the smoke fan Mark ?............  I was hoping that was the issue for the Mallet.    Tracking down wiring issues is a PITA .

Just glad it wasn't the board in the tender.

@Dallas Joseph posted:

How did you test the smoke fan Mark ?............  I was hoping that was the issue for the Mallet.    Tracking down wiring issues is a PITA .

Just glad it wasn't the board in the tender.

Dallas, I was able to spin the fan and motor shaft easily with my fingers, so knew the fan wasn’t binding.  I didn’t know what voltage I should see on it, so I ordered a pack of 5 motors from MTH, and just replaced it.  I got it right on the first guess.  They only came in packages of 5.  If the engine had been a beater, I may have played around with the meter, but didn’t want to risk shorting something out on an otherwise perfect engine.

I guess my best lesson learned from working in electronics is to have a respect for electricity.  The second is, when it was company work, mistakes didn’t come out of my pocket.  Not so with government work!  😉

@Mark Boyce posted:

Dallas, I was able to spin the fan and motor shaft easily with my fingers, so knew the fan wasn’t binding.  I didn’t know what voltage I should see on it, so I ordered a pack of 5 motors from MTH, and just replaced it.  I got it right on the first guess.  They only came in packages of 5.  If the engine had been a beater, I may have played around with the meter, but didn’t want to risk shorting something out on an otherwise perfect engine.

I guess my best lesson learned from working in electronics is to have a respect for electricity.  The second is, when it was company work, mistakes didn’t come out of my pocket.  Not so with government work!  😉

Mark , I  momentarily touched the MTH rechargeable 2.4 volt green Ni-MH battery to the disconnected fan motor leads to test the motor.   

   I agree with you about the risk of shorting something out .  I won't do anything myself with the engine powered up .   I'm  only brave enough to check for continuity with the VOM.

That was a good idea using the battery, Dallas!  

Simplest way to do this, is unplug smoke fan motor connector and plug in 6V bulb.  If it lights the board and harness is good.  Despite all the testing methods I have seen stated, or the don't use a 9V battery blah blah blah.  If the smoke fan motor is much less than 12 ohms it is failing.  It will start drawing too much current from 5V power supply, and ultimately become noisy and or fail.  If it is soaked in smoke fluid regardless of ohm reading.  I replace it.

Granted not all premier steam are easy to observe, but for most engines watch the smoke fan with shell off.

99.9 percent of the smoke issues with mth are bad harness/wire connection, bad smoke motor, loose fan impeller or bulging gasket impeding impeller rotation, board fet, burned wick.  Burned wick is not replacing fluid or fan stopped turning.  Rarely do I have to replace the element even on poorly maintained smoke unit, and I can't remember the last time I replaced the smoke heat fet on PS-2.  I still have the original ones from the service kit when I first became a tech.

Measuring voltage is not a good test.  It is unloaded test.  No current draw.  I have seen good continuity checks but no current flow under load because of bad solder joints or broken wires.  Let alone if you're not careful and short the probe to ground, poof!  So use a 6V bulb.  HL bulb works fine.

For a new motor I drop a spot of oil on the shaft bearing, pre solder the leads, then hit it in both directions with a 9V battery for test.  Make sure impeller goes on firm, and seat deep enough to clear gasket.  When an engine doesn't smoke when it should see the list above.  When an engine misbehaves with motion and or constantly turns on and off at application of power, check it with smoke off.  If that restores operation 99.99% of the time it is smoke fan related.  If smoke off still acts up, it is battery, audio amp or other board related problem.  G

@GGG posted:

Simplest way to do this, is unplug smoke fan motor connector and plug in 6V bulb.  If it lights the board and harness is good.  Despite all the testing methods I have seen stated, or the don't use a 9V battery blah blah blah.  If the smoke fan motor is much less than 12 ohms it is failing.  It will start drawing too much current from 5V power supply, and ultimately become noisy and or fail.  If it is soaked in smoke fluid regardless of ohm reading.  I replace it.

Granted not all premier steam are easy to observe, but for most engines watch the smoke fan with shell off.

99.9 percent of the smoke issues with mth are bad harness/wire connection, bad smoke motor, loose fan impeller or bulging gasket impeding impeller rotation, board fet, burned wick.  Burned wick is not replacing fluid or fan stopped turning.  Rarely do I have to replace the element even on poorly maintained smoke unit, and I can't remember the last time I replaced the smoke heat fet on PS-2.  I still have the original ones from the service kit when I first became a tech.

Measuring voltage is not a good test.  It is unloaded test.  No current draw.  I have seen good continuity checks but no current flow under load because of bad solder joints or broken wires.  Let alone if you're not careful and short the probe to ground, poof!  So use a 6V bulb.  HL bulb works fine.

For a new motor I drop a spot of oil on the shaft bearing, pre solder the leads, then hit it in both directions with a 9V battery for test.  Make sure impeller goes on firm, and seat deep enough to clear gasket.  When an engine doesn't smoke when it should see the list above.  When an engine misbehaves with motion and or constantly turns on and off at application of power, check it with smoke off.  If that restores operation 99.99% of the time it is smoke fan related.  If smoke off still acts up, it is battery, audio amp or other board related problem.  G

Thanks George .      A ton of good info here.               In general the articulated engines with their shifting driver motors pushing and pulling on wires inside the shell causes issues .

I'm glad this was a 3 volt ps2 .   Whenever I  look for a used engine I make sure it isn't a 5 volt or less since I am currently running the full DCS system and can't afford too many good looking door stops.

My only problem yet is with my RK ps3 Allegheny.  Still trying to find a boiler board for it.    No luck so far.

Not really.  All the wiring is in the shell which does not move.  A 10 pin connect down to a fixed PCB.  The only movement of wires would be the lead drive block power pickup.  That is the only point moving.  Shell is fixed to rear truck/frame.

Some units do get wires that go brittle.  Not sure if it is how made, or oil fluid from smoke unit that hardens the insulation.  Sometimes a poor solder joint to the molex plug hidden under heat shrink.  G

George, thank you for the great tips!  Yes, on mine I was thinking about whether I would get a valid reading unloaded and afraid my probe would slip and I would fry a board.  As I said yesterday, I’m always cautious, but my hand can shake making measurements.  I’m copping your tips for future reference!

@GGG posted:

Not really.  All the wiring is in the shell which does not move.  A 10 pin connect down to a fixed PCB.  The only movement of wires would be the lead drive block power pickup.  That is the only point moving.  Shell is fixed to rear truck/frame.

Some units do get wires that go brittle.  Not sure if it is how made, or oil fluid from smoke unit that hardens the insulation.  Sometimes a poor solder joint to the molex plug hidden under heat shrink.  G

Would you recommend removing the rubberbands on the motors that retain the wires George ? 🤔                      I  do have O31 curves and switches included on the layout and when I have the boiler shell off I noticed some movement of the wires when the motors in the articulated engines are going through  left and right turns and switchbacks.

On some of the wires in older engines it seemed that the insulation might be getting softened from smoke residue near the front of the engines and then maybe drying out over time the insulation hardens and becomes  brittle.       I only saw wire insulation in one older switcher splitting on the yellow and white motor leads at the motors.

Thanks again for your replies.

@Mark Boyce posted:

George, thank you for the great tips!  Yes, on mine I was thinking about whether I would get a valid reading unloaded and afraid my probe would slip and I would fry a board.  As I said yesterday, I’m always cautious, but my hand can shake making measurements.  I’m copping your tips for future reference!

Yup , really good to have techs onboard.

@Dallas Joseph posted:

Wanting to insert a reply to a different topic thread.

Do you mean like this?

@ADCX Rob posted:

Do you mean like this?

Yeah Rob .   How'd you do that.

Also if it would also transfer the video with the reply ?

Thanks for your quick response.......I couldn't see anywhere how I could do this on my Android  Tab A though. 🤔

@ADCX Rob posted:

Do you mean like this?

Rob , I use a Samsung Tab A.    I did a pdf download but to open it was going to be a PITA App or have to pay App.

I was actually able to do a screen shot and insert the reply with video as an attachment.     The video of course qualified as only a photo.

@Dallas Joseph posted:

Yeah Rob .   How'd you do that.

You just do a new reply, use Ctrl-X to cut the entire reply from the reply box, go to the new thread and paste that into the reply box.  Here's an example from a random thread.

@David Johnston posted:

The lower roller is part number 397-12. That is not to say you will ever find it as a separate part.