ps2 wireless draw bar runs rough

Rider,

This is certainly the correct place for your post!  

What do mean by "runs rough"?

Without the smoke unit, it glides along steadily down to 3 or 4 mph. With the unit on, it stutters along. It no longer runs smoothly. I am guessing the circuit driving the smoke unit can't handle the added load but I have no way of knowing for sure.

I'd be looking at the tether and associated connections really close on this one.  The electronics is in the tender, so the power has to go from the locomotive to the tender.  If there is a high resistance there, that's all it would take.

Thanks much for the reply. Since the problem is not there when the smoke unit is off, I would think a high resistance would not be the answer. A higher resistance would decrease the load. Resistance is infinite when the unit is off. The draw bar has been replaced some time ago and made no difference. However, I do think the problem could very well be in either the tender harness or engine harness. I have visually examined them both with a magnifier look for bare or shorted leads but have found none. Thanks again you reply is greatly appreciated.

Bernie

Could there be a partial short between one of the smoke unit wires and motor wires In the tether or at the connectors?

I have no idea which pins do what. Maybe one of the MTH guys could comment.

Pete

You obviously misunderstand what I'm saying.  If the power from the pickups has any significant resistance in the feed to the PS/2 boards, any additional load will drop the voltage coming to the boards.  You could have a voltage drop without the smoke unit, just not enough to cause you issues.

High resistance could certainly be the issue, it all depends on where the high resistance is!

Pete, if there was a short between the smoke unit wires and most anything, I suspect worse things would probably be happening.

About a year ago, I removed one of the heater coils from the smoke unit to reduce the load by half and see what difference it would make. The answer was surprisingly little. The engine performed about the same way and the smoke volume didn't seem reduced by much at all. 

Bernie

When this occurs many times it is the fan motor going bad.  Change the fan motor.   G

Thank you GGG, I'll try that. I think first, I'll just disconnect the fan motor and run the thing for a few minutes and see what happens.

Bernie

Just a minute.  Without air movement, the wick can char. Make sure it is wet.

If this model has the MUX we can go from there if the fan motor isn't the issue, but this normally fixes those issues. G

This engine does have the MUX. I won't run it without the fan but for a few seconds. Just long enough to observe results.

BVernie

I disconnected the fan motor, ran the engine and symptoms were same. I reconnected the fan, disconnected the heater coils and it ran like a charm. This seems to confirm my prior belief that whatever circuit is driving those heaters cannot handle the load.

I'm back to my original diagnosis, check the wiring that provides power to the board from the locomotive.  You have the pickups and their connections, the tether, and the wiring in the tender to the boards.  That's a pretty long path with a number of places where you could be experiencing a high resistance connection.  Any significant voltage drop there would be greatly exacerbated by the addition of the additional 1/2A of the smoke heater.

Will do. Thanks much.

Bernie

I don't believe it would be an input high resistance other wise the light and motor would also trigger this behavior.

Now that it is isolated as the heater only I would check/trace the brown heater wire which is return.  Since purple is hot all the time it should not be the issue since even with smoke off it could cause issues.

So make sure the heater element is not touch the smoke bowl on the Brown wire side, then make sure the brown wire doesn't have a pinch, or knick and touching chassis frames somewhere. 

The load of the smoke unit is not so great that it would normally cause this.  It only adds about .6 to .7 amps against a rectifier capable of 8 amps.  Since you have removed one resistor, your pulling even less.  So the wiring on the return side or the element touching the bowl are suspect issues to check.  Than we move to the MUX in the engine.   G

My "guess" is that when the voltage drop exceeds a certain amount that it affects the board's operation.  It may well be something else.

One way to see if this is a possible issue is to run at lower voltages on the track.  If it's a voltage drop like I suggested, the engine should have a problem at track voltages that it should have no problem running at.  If it can be triggered without ever turning on the smoke, it would indicate the smoke itself isn't causing the issue, but rather the current draw and/or voltage drop.

I'm not suggesting you're overloading the rectifier, but rather a high resistance somewhere in the power feed could be dropping the voltage below the usable threshold.

In any case, examining the wiring can't be a bad thing.

Isn't this a case of the "flickering light syndrome" that people addressed a few years back? Mine was repaired by Dick Teal but I'm not sure exactly what he did. Some re-wiring was called for. Ask MTH what the cure for flickering light syndrome was.   Joe

To GGG, Gunrunnerjoh, and Rigatoni.

Thanks to all for the suggestions. I think you are all on the right track. A couple of years ago, I spent a day Replacing all of the active components in the engine and tender. The main circuit board module, the mux boards, even the speaker, the battery and light bulbs (it now has a BCR). After each component was replaced, I tested the engine.  Nothing changed. That's when I began to suspect either a wiring problem or an inherent design flaw. That's also when I removed one heater coil. 18 months ago, I was put out of commission by a serious back operation that took me away from my trains (and everything else) now I'm back trying to nail down this problem. Yesterday, I began tracing and OHMing the engine harness to see if the connections had high resistance or leaking to ground anywhere. I started to replace the MUX board but that has already been done. I was interested to see the "flickering light syndrome" Rigatoni mentioned. The cab light is on the same circuit and the heater coil and it flickers when the smoke is on. I would like to ask Dick Teal what he found. Got to go now but like a bad penny, I'll be back!

Bernie

This is a PS-2 3V model.  The Flicking light syndrome was the early PS-2 5V models with the MUX board.  MTH corrected this on later run 5V boards, and it is not a symptom for 3V systems.

For your model, the Engine MUX board produces the Positive voltage for the engine lights, and heater (purple wire normally).  It comes from the voltage applied to the Motor and those motor leads feed the MUX board.

So pin 1 out of the engine mux is purple to the smoke unit heater (also engine lights).  The brown on the smoke unit heater goes to the engine harness PCB pin 2.  This may run through and intermediate 10 pin connector on the engine frame.

From the engine PCB pin 2 via the tether to the tender harness.  Inside the harness it goes to pin 3 of the 4 pin connector on the board.

I still suspect the brown wire path from the smoke fan back to the PS-2 board (Check Pin solder connection for broken solder joint at pin 2).

BUT: look at the white and yellow motor leads from the motor to the mux board (solder joint at the motor or nick in those wires. Since this feeds the MUX to make PV.

Or a faulty MUX board not producing a good Positive voltage.  In this case loose pin connection inside the connector may not be making good contact.

Based on all the other components you changed, I do think the wiring harness or the connector pins of the the connector that plugs into the mux could be your issue.  A previous pinched brown or purple to the smoke fan, or their associated contact pins may not provide sufficient continuity for the smoke element.   G