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Working on a 2.0 3v w/Mux Rail King Big Boy.   Everything works except for the smoke when moving.  Smoke works in neutral, but as soon as the movement starts no heater smoke - I can feel the fan motor moving.   Placing the circuit boards on the board tester works, but isn't a true simulation due to no Mux boards.  I've tried replacing the Mux boards as well.

I don't have any other 2.0 steamers with Mux boards in my possession to try a tender/boiler swap (which would narrow it down 50%).

I've seen similar issues (quite often  actually) where it is the speed control sensor or wiring - but in all of those cases there usually is no speed control or chuffing sound.

Work on hundreds of train items a year, but every once in a while one stumps me.  Ideas?



Jim

Last edited by Jim Sandman
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Check the impeller on the smoke fan. If you can easily pull the impeller off the fan motor, there is a good chance it is not tight enough on the fan motor shaft to work correctly.  In idle, the loose impeller can keep up with the shaft, but when you move, the fan motor stops and moves suddenly for each chuff and the loose impeller just spins on the shaft generating no puffing.  I have seen this quite often.

Brian

Found the issue!

First Lou1985, the wire tie combining the blue wires to the Mux board was only a few strands making contact - soldered now.

Mr. Macher I found it before I read your post - but you are the winner!

The issue turned out to be the smoke propeller!  In neutral with full on spinning it would catch and spin, but in chuffing mode the fan motor moved but not enough to spin blades fast enough.  I changed out the motor too just for good measure since it had been heavily used.

The other items I fixed tonight went fairly well - Lion Chief 0-8-0 Drawbar, Lionel TMCC B&O EM1 loose R2LC & Motor Flywheel loose, Polar Express smoke unit.

Jim

Last edited by Jim Sandman

So your symptom was wrong.  "No smoke heat".  So some guess got it:-)   Heat is easy to see with amp meter.  Turn smoke on and see a jump in amps.  If no jump there is a heat issue.  That is PV and PS-2 board smoke signal.  Nothing to do with MUX.

Since MUX had fan working in idle and I assume you had chuff with no smoke in motion, that narrows it down to the impeller usually.  Only smoke fan runs through MUX with tach since 5V and tach signal ground comes from MUX.  If you had no chuff, speed control or smoke fan, that points to mux issue or the wiring.  Notorious for bad solder joints of wire to connector under heat shrink.  G

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