PS2 probelm, need some advice

Did you try a conventional or DCS reset?  Joe is right about tether.  You also can have a bad smoke fan, so be careful as the heater may still be on, but no air to move smoke or cool the elements.  G

Thanks guys, I haven't tried a restart to the system yet, I'll do that tomorrow. What I did do was swap tenders as I have two 260's. The problem stays with the engine and not the tender. So I guess if it's a tether problem it would have to be the port on the loco and not the actual cable from the tender.

As far as opening it up and taking a look, I'm always willing to give it a try if it will fix the problem and save me some money but I'd have no clue what to look for.

Not sure of the specific model, but the board is in the tender I believe, so that eliminates a lot of issues with the tender swap.

I would check wiring and pin connection on back of engine.  If this has the diodes under the PCB on the engine it could be that one is bad.  That makes the positive voltage for the heater element and the lights in the engine.  I believe headlight and firebox are on the same circuit.  Turn volume down and see if you can hear the fan run with smoke on?  If so, that does point to the Positive voltage circuit not functioning on the engine.  G

Hi All,

So I just turned the volume control all the way down, gave the train some throttle and it started to creep along the track, it should have been in neutral but it goes at a very slow speed. I can hear the fan running and even felt the air moving out of the funnel but no smoke and no lights. I then hit the direction button and it took off in forward under normal control, still no smoke or lights.

But wait there's more.

I hit the direction button two more times for reverse and all of a sudden, lights and smoke!. I put it back into forward and still no lights or smoke but the fan is going. So I have an engine that works great going backwards. What could possibly cause that?

Thanks,

Sam

maybe a short in the headlight....

or the engine has vertigo? (or whatever U call it ...

Does the behavior change if you turn smoke OFF?

The diodes are just common 1N4003 or similar diodes, you can pick them up almost anywhere, even Radio Shack.

Take the board out and you can just pop the diode into that spot.  Obviously, make sure the stripe is oriented properly like the old one.

Hi All,

Thanks to everyone's help I got the diode replaced and just ran the train. Everything is working as it should. And the best part is the total repair bill, minus my time was $.25 for the diode, can't beat that.

Thanks again!

Sam

Since the diode is used to generate the positive voltage for the locomotive stuff, I suspect that draw of other stuff in the engine was enough to put a bit of voltage on the motor when it wasn't supposed to be moving.  The two diodes just allowed MTH to work with one less wire in the tether.

Stan,  Yes a purple wire short is possible, but as I look at Sam's picture it looks like it may have been pressed against the frame.  Even the connector edge is bent over.  I would insulate under the PCB.

Any damage to that diode can cause issues with motor performance as your shorting either PV into the motor, or bleeding voltage on to the PCB Ground return or shorting to Chassis ground.  Since PV is made right at the main rectifier, a short of PV to ground is not catastrophic just a heavy load on the rectifier.

Once we knew the fan was running the PV was my top suspect, especially after everything came back to life in reverse.  The way the relay work, there is always positive voltage at either Yellow or White wire.  The ground return is what keeps the motor from spinning.   G

I suppose we'll never know but in replacing the diode and re-installing that small board with the 2 diodes,  a short to the frame - a potential root cause - may have been removed.  Insulation would be great idea.

Insulation would be a great idea Stan, I agree with that.  I've moved those diodes on a number of upgrades because they either didn't fit, or were so close that I figured the danger was there.

It is pretty easy to trace the PV wire to see if one was crushed.  The only other potential short is the PV side of the heater element to the housing frame, but MTH units don't normally have the problem.  So unless some one was in the smoke unit and bent the element...

MTH has an insulator that raises the PCB that comes with the kit.  I have used that to gain room under the PCB, and I normally insulate to be safe.  G