Proto 2.0 experts needed

 I believe if you do a search for wiring the mux board(?) or something like that, it might cover the problem?

I believe a wire needs to be switched out or added, to keep this from happening on the Y6.

 Hmmm, several different smoke issues I've heard, not matching this one. If the fan blade was lose, maybe it would have that symptom? Shut off the sound and listen to hear the smoke unit chuffing at slow speeds in sync.

 I bet the guys will post in on better ideas.

Sounds like bad fan motors.  On MUX units they can cause lights to go out. Flickering lights is a different issue.

 

On the Dreyfuss, does it chuff correctly?  In neutral smoke is on, but when moving tach signal creates the chuff.  So this can be a tach reader issue or the fan motor is going bad.  G

I purchased a used MTH 4-12-2 UP 9000 having an issue of flickering lights when the smoke unit activated for each chuff.   MTH suggested replacing the drawbar because of a known circuit trace issue inducing noise into other conductors on the draw bar.  Major improvement after replacing this piece.

 

 

There is a service bulletin that has a procedure of what to do for the flickering headlight issue that involves moving wires and other things. One of the guys in my club has the same issue when in DCS mode but not in conventional mode. Try running conventional and see what happens and report your findings.

I will replace fan motor and see but it just seems odd to me that it works so well in neutral. Chuffs are correct.

This one has the wire not the drawbar. I wish it did because the drawbar is easy. Thanks.

That is a good suggestion. Thanks.

I am beginning to think it is that wire. Thanks.

A lot of misinformation as far as applicability to the symptoms you state.  Specifics matter.  If you turn smoke on and the headlights and markers go out or both go extremely dim, the fan is drawing excess current and the MUX board can't supply it and the lights being driven via the MUX go out.  The fan is driven by 5V DC the same power supply that provides the fan power, supplies all the microchips including the 3.3V power supply for the main processor/memory.  That is why a motor that starts to draw excess current can effect board operation.  This has become very common.  Even had a working fan arc/short and cause sporadic bell whistle signals.

 

The flickering light is just that, flickers and it only applied to PS-2 5V boards.  Certain engines before the mods where made.

 

The no smoke in motion is driven by the tach, speed amp and processor which fires a FET to stop the fan by sending 5VDC vice ground to the terminal.  You may have a bad fet. if it still has speed control and chuff sounds then the tach is good and the board may have faulty components for controlling smoke fan.  Of course the fan motor can be bad also.  Getting full voltage in neutral keeps it running but the stop and go not keeping up.  As stated loose impellers also can do this.

 

So you can change fan motors at $6ea as the easy first step.  G

Thank you for your informative reply. Both problems are caused by fan motors. Thank you!

So that fixed them?  Good to hear and glad to help.  G

I have to put the fans in and I will report back. Thanks for your help.

New Fan Motors fixed both Locos. Thank you!

Thank you for the feed back.  Glad it was simple.  G