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I have an MTH PS2 cab forward. TIU is Rev. L.  Track voltage is set to 15 according to the analog AC voltmeter in the track power circuit. Voltage above 15 results in flickering marker lights/cab light/firebox glow light.  Turning off the smoke unit alleviates the flickering, but bumping the voltage to 18 causes the flickering to return.

 

The main problem I am now experiencing occurs when the engine goes through a couple of turnouts (an S, right to left) and the bell is turned on at approach to a station, smoke unit on. This results in a significant drop in engine speed. Turning off the bell results in an increase in engine speed to what the throttle was set at.  I usually run the engine at scale 15-16 mph on the layout - the speed that appears on the controller screen.

 

The previous time the lights flickered (a few years ago) I sent the engine back to MTH and the MUX board was replaced. At that time it was recommended that the track voltage be set to max 15 volts.

 

I’d appreciate any insight you folks might have.  Thank you.

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A reason why? Not really. Maybe the higher track voltage plus the electrical load with the smoke unit on caused the MUX board to hiccup. There was a comment to that effect on this board some years ago, I believe. Flickering lights continue to occur now with smoke unit on and track voltage up around 17-18. The engine runs OK at 15 volts except for the situation I described above. In one of his reviews in OGR, George Brown mentioned that he sets track voltage at 15. That might be a safety reason to eliminate turnovers on his CCRR.

Your engine is a PS-2 3V so the MUX board flickering light issue from the PS-2 5V period should no apply.

 

I am also baffled why MTH would recommend 15V.  Normal Is 18-20.

 

For your engine 5V power is sent over to the engine and runs the MUX board.  The smoke fan, markers and tach would be run off the MUX board connection (usually).

 

I would replace the smoke fan motor.  It may be drawing too much current.  G

GGG, 

The smoke fan motor is new from MTH, a week ago. Old one was noisy.  Same flickering lights situation exists as described above. If I reduce the chuff pulses from 8 to 7, or 6, or 4, the flickering goes away until the track voltage is upped to 17-18. I do not use a battery in this engine, I use a BCR unit.

May want to look at MUX board diodes.  I am also concerned about the speedup slow down in curve, especially if not seen before.

 

This one seems more complex.  Are you sure you did not damage the fan motor with too much heat when soldering in?

 

Not sure this can be fixed over internet unless you get lucky.  I would start isolating components but you need a bench tester to do it efficiently.  G

I was searching around and came across my earlier post and replies about the smoke unit on the PS2 20-3347-1 cab forward. Having same problem again. I bought a new fan motor from GRJ and installed it about 2 months ago. No change. Engine runs better without the smoke unit turned on. Track voltage is 15, any higher and class lights/cab light flicker. Have not discovered any binds in the mechanism. At this point I'm ready to buy a completely new smoke unit from MTH, but can't find a part number. 

I was running it a few minutes ago, and when I pressed the smoke button and turned off the smoke, the headlight, cab light and class lights turned off! Used the LIN key along the bottom of the screen, and the headlight button on the remote and turned them back on. But why would the lights go off? It's happened previously, but it is annoying when it occurs. The tether is a pcb, and it's tight in its socket. I set the voltage at 15 because the lights flicker above 15 volts.

Last edited by mtnhi7

George, I remember something crazy like that a few years ago on my engine and it turned out to be the ground (black wire) wire needed the screw to be tight.  It was a bit loose and caused an issue.  As we know, the short black wire screws into the board hole to ground and then to the two pin plug on the edge of the board.   Again, a board issue should be eliminated by throwing the boards in a test fixture and then I am on board with you with the Mux.

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