Loco surges when smoke unit is on

 Depends how good the tech is at the LHS.  I would start by looking for pinched wires.  Then I would isolate the smoke fan and see if the behavior remains, then the smoke element.  It is possible the smoke element is shorting and drawing too much current.  Can you read amps when the engine is running?  Or the smoke fan is going bad and causing problems with the +5VDC circuit which impacts all the processors that use 5 vdc.  If this is under warranty I would send it back to MTH.  G

Thanks for the reply G,

 

This is actually my engine, Stuart was at the layout today and asked the question for me.

 

The train has been running well for the past few weeks, several hours a day.  The smoke gets used occasionally and only for a few minutes at most for demonstration. The surging started yesterday afternoon when I tried to use the smoke.

 

I really hope it does not have to go to MTH - it is a co$tly trip if it does.  The loco is not under warranty.

David,  Hopefully you have a MTH trained tech in the area.  I have not seen this issue before, but based on how the boards work, that is the direction I would go.  A tech with a board testor can test the board without your engine harness and smoke unit in play.  If it works fine in the testor, then it is a harness or smoke unit issue.  Good Luck.  G

Sometimes when the smoke function is turned on the locomotive starts to run away (speeds up dramatically), and won't respond to DCS commands until the smoke function is turned off.  To stop the runaway I hit the direction button and the locomotive didn't respond.  Once I turned off the smoke function the locomotive came to a sudden halt, and then I was able to run it in reverse.

 

Stuart

 

I wonder if disconnecting the battery for a while would help?

I had a Yellowstone steamer do the same thing a year or so ago.  I took apart the smoke unit and found the wick had charred enough to short when the smoke unit was turned on.  I removed the charred portion of the wick and moved "fresh wick" in between the elements and the problem went away.  Good luck!

Is the smoke unit on your steamer working, when turned on?  I was having an issue with a PS2 steamer, where the steam fan wasn't working and the engine was surging/running oddly.  Turning the smoke off resulting in flawless operation.  I found several issues on this forum pointing me to the tether cable.  Investigating that, I found that straightening the cable resulted in everything working again.  I've replaced the tether, and so far so good!

 

Sam

Stuart.  Unplug the smoke fan and try it.  Since you are losing speed control (tach is driven off the 5V circuit), I think the smoke fan is going bad and causing your troubles.  If unplugging the smoke fan cures this, replace the smoke fan motor.  G

Well, I took the shell off and examined the locomotive.

I looked at the wick, it was scorched between the coils, so I moved clean wick in there per Rog's suggestion (didn't help).  I noticed that the smoke unit fan is not turning at all.  So I'll run it without smoke for now and we'll order a new smoke unit after the holidays.

 

By the way - running the locomotive with the smoke unit unplugged - either the motor or both plugs (smoke element and motor) resulted in no control, just fast speed.

 

Thanks for the help so far.  If anyone has other thoughts, feel free to post!

You can replace the fan motor, it's a simple operation. 

Does this have the boards in the tender and use a MUX board?  When you unplugged the smoke element and the fan was it at the smoke unit?

 

I would make sure the 12 pin plug in the PS-2 board is seated firmly, I would also do the same with MUX board plugs if this engine has them.  For MUX board engines, the shell must be on (MUX unit attached) for the engine to have speed control.

 

No pinched wires?  A picture would help.  G

We had the whole unit apart today - loco and tender.

I was able to run the fan motor all the way back to the circuit board plug with a 3 volt battery supply.  The fan motor works.

 

We tested the loco with the shell off on conventional power and the smoke ran fine.

We then put everything back together and tested again - still OK.

Next, onto the DCS layout.  The loco ran fine, smoke on.

I turned off the smoke and turned it on again - back to square one - surging.

 

I have ten PS-2 locomotives - this would be the third failure.  Not a good track record.

Did you record the amps the smoke fan was using?  A battery can source a lot of current.  I have had motors work on battery but not so well on from the circuit board.

 

The 5V power supply chip on a PS-2 is rated at 1amp and has to power about 10 microchips, the tach reader, MARS, Markers and Fan motor, and speaker. 

 

This is interesting and it doesn't explain some of your symptoms from before.

 

So if you unplug the smoke fan, does it still lose speed control or surge?

Check for a break in the tender wire. Ohm out each connection I think you might find it is bad.

When you're checking the wires as Paul suggests, wiggle the wires as you take the reading to make sure you don't have a broken wire that sometimes connects.

I have done the unplug & wiggle stuff.  No joy there.

I have run the fan on 3 volts from a battery set all the way from the circuit board plug, so the wiring system seems to be fine.

 

Unplugging the fan motor and smoke heater coil inside the locomotive result in erratic running and loss of control.  I have not had the chance to test the engine with the smoke harness unplugged from the tender board.

Dave,  If you unplug the 4 pin from tender board, while leaving the fan and heater unplugged and the engine returns to normal I think some where along the 4 smoke unit wires is a short among the wires.  Could be inside the tender, engine or the tether.  Depending on how the wires are routed they could be knicked and grounding out.

 

If even after the 4 pin is unplugged the erratic behavior remains but tends to go away when smoke unit is plugged in, I would start looking at the boards.

 

Testing boards can really help the troubleshooting.  G

The locomotive came off the display layout today, so I can spend some time trying the various harnesses, wiring and plug combinations again.

 

Of course there is always the chance that it's something in the store TIU that's causing the glitch and it will run fine at home (well, I can dream, right? )

What a coincidence, my MTH (???) that is part of my Christmas only layout started to do the very same thing at about the same time as the first post. Conspiracy Theorists - Where are you? 

New Battery

Moved Wick

Smoke Fan Works

No apparent wire breaks/shorts (Wiggle Method - The wire, not me!)

 

Needless to say, I am tracking this post closely and anticipate the identification of a resolution...

Attached is my Main Level Christmas Display for 2012.

D'oh!

MTH 30-1187-1 4-6-2 Pacific Steamer

 

So the latest on my unit...

Symptom Observations:

1. Runs fine w/o smoke

2. With Smoke. Blammo! Symptom appears.

3. Unit surges, then may shut down.

4. Unit runs fine with smoke on straight and right curves

5. Left curves and Blammo! symptom appears. Requires shutdown and restart with smoke on/off cycles to gain smoke again.

6. Moving the tether harness and nothing happens, but notice a sporadic spike in Amps on K4000. Sure enough while running when symptom appears there is a spike in Amps as well.

 

Appears we have short Captain!

7. Use needle nose and start to squeeze tether cover and see Amps spike as I get closer to the connector.

8. Fresh blade in utility knife and make a shallow incision in the cover

9. Wires have white substance on it, I assume Talc to facilitate wire bundle though tether casing.

10. All wires seem snug/secure, except gray wire that ends up stretching/breaking.

11. Reattach tender and engine, no short apparent.

12. Rejoin gray wires and Blammo! Unit has interruption in signal and shuts down.

 

Short appears to be in the connector.

Now to locate the proper MTH tender harness number and get an estimate for service vs. I dig in a little deeper and do the labor myself...

 

So how does it run with the gray wire detached?  All features including speed control, possibly no smoke.  Or have you lost speed control?  G

I must say, in the months I've been following the Forum... OK lurking on PS1 Issues. :-)

To have you Mr. G, respond to my first post is quite an honor.

I recognise you as informed and objective... Though I did get a kick of you and a certain someone else go back and forth discussing PS1/PS2 Batteries... Too funny.

Sounded like my kids. "no it doesn't, yes it does, no it doesn't". I even read an "I'm telling" in the salvos going back and forth.

 

To answer your question - Yes. All functionality (speed control/whistle/direction) has returned. when I select smoke though, it acts up regardless of speed or turn with the wire detached.

I suspect, what was an intermittent short is now solid as I pulled on the tether wires.

 

I have an email into MTH for a new Tender Harness part number.

As you can see in my pdf attachment, my Christmas Layout is no small effort, but I enjoy doing it tremendously. The smoke is a nice addtion for showing off my display, especially when I can throttle it to blow rings and all remotely.

Thank you Gramps.  No problem with passion as long as respectful:-)

 

Have you opened tender?  Normally the gray wire is the +5VDC for the smoke fan.  Since that lead is broken,  the tach should not have power so the engine should not have speed control or syncronized chuff.  (You imply that it does).  Since it only shorts when smoke is turned on, I am thinking the fan return wire is shorting and causing the board to shutdown or operate erratically.  The gray wire would normally always have +5VDC present.  Since the side of the harness towards the tender is still engergized from the board the short is on that side of the harness.

 

If you look or send pics of the tender harness it maybe the external version with plugs at both end.  If so I can give you the number.  I have one in stock.  If it is custom single piece unit, if MTH is out, you will need to order the universal one and splice it in.  

 

I would also be careful testing the splice while energized.  You don't want to have a spike take out the board.  I believe this is the early PS-2 5V set up.  G

Full Speed Control and Chuff Rate. It is the fan motor wire. I can hear it when I touch wire ends. Unit is from 2001. Harness appears to have at least one plug at the tender... I haven't clipped zip tie yet until I have a solution.
Touching, moving harness near tender did nothing. It wasn't until I got close to engine I could isolate/rtepeat the short. So I started to cut casing and pull. With the broken wire I have to replace now. I will further decompose the original cable to locate the short/break... Board/Wire inspection as well.
Fortunately it behaved when all the neighborhood kids stopped by before Christmas.