Continuing MTH Erratic Behavior Question

Engineer-Joe posted:

PJB posted:

Gregg posted:

Is this happening with lash-ups or long heavy trains?  You may be pushing the limits  of the engine. Does it happen  with just  the engine?

Engineer-Joe and Gregg - just the locomotive. No lash-ups, no cars at all. Going anywhere from 10 smph to 60 smph.  Thanks for your help.

Peter

whaaatt?

I asked if you tested the track under load, not the engine.

Yeah, well, I'm not an electrical guy, so didn't get that the first time  

So, if I'm understanding you correctly, you're saying run the locomotives that give me problems (again, I run them without any cars and experience this issue) and when they are - where? in the same track blocks where they experience the issue? - use my multimeter to test the track power?  

Update - 

I did as you all instructed.  I checked the wireless drawbar. It needed half a revolution to get it tight, although it wasn't at all loose before I did. I checked the track voltage in every block as my Mohawk (most problematic locomotive) went through it.  It registered between a solid 18.8 and 19.01v (every main is powered by a Lionel PH 180 brick).  Despite this, when I put my teeny tiny never-ever-maintained 1973 Lionel Southern Express locomotive on the track (does not require a tender, and only put 5.5-6v to the track to keep it at a low speed), it occasionally crapped out?!  More amazingly - at times when it was traveling at approx 15 smph in forward, it jumped into reverse!  So, I added jumpers between the outside rains in every block.  Now, the Lionel SE runs perfectly and all Premier locomotives no longer do the slow down/speed up two-step!   Nice smooth runners again. 

Thanks to all who were kind enough to lend a big helping hand!

Peter

Thats great Peter you got your problem solved!

Yes, thanks to all the help I got here.  The thing that bugs me, however, is that I like determininh the root cause of an issue so I know what the fix is if it recurs. Here, I still don't know what "fixed" the issue, given the signal was a perfect 10 and the multimeters say every block was correctly powered at all times.  Hmm.....

So, I added jumpers between the outside rains in every block.  Now, the Lionel SE runs perfectly and all Premier locomotives no longer do the slow down/speed up two-step!   Nice smooth runners again. 

Gregg posted:

So, I added jumpers between the outside rains in every block.  Now, the Lionel SE runs perfectly and all Premier locomotives no longer do the slow down/speed up two-step!   Nice smooth runners again. 

Gregg - I take it you're saying the jumpers fixed the issue?  If so, can you say how?  I'm not an electrical guy and if the track is already getting perfect power and signal then what do the jumpers add to make 'perfect" more perfect?  Thanks. 

 My best guess..  MTH steamers especially  the  2 / 3 rail variety  are not great at picking up power from the outside rail.  There's a limited number of wheels that pick up the outside rail power.  I think it's the  left side engine drivers and the right side of the tender trucks. Traction tire can also be a factor... Jumpering both outside rail together increases the odds.... Not exactly like our old Lionel engines where all the outside wheels pick up power.    . 

Ok, I just learned something - thanks!  

Same problem with a PS3 Mikado.  My other PS3 Pacific and all my PS2s work fine.  This one was from the line of Mikados produced by MTH in 2016.  The 2018 Pacific works fine.  I also notice if you run up the thumbwheel even to 100 the speed stays the same and if you press direction it takes a long time to slow down as if it were going 100.  This happens no matter how many cars, and it will perk back up by cutting the smoke unit which I need as this is a museum layout.  I also have a Premier 2006 Mikado which has no problems.  Signal is 10 and is running off an MRC brick with a voltage reducer that produces 16 volts.  Without it would be 20.

With that loco selected, MENU/CONTROL.  Check ACC & DEC rates.  I use 1 for a gentle stop & start.

It's only the one ps3 that misbehaves on some stretches with the smoke unit on.  Runs perfectly otherwise.  Wondering if running a heavier jumper wire to those sections would help, or removing the voltage reducer from the line

What, pray tell, do you mean by "voltage reducer?"  Electronically, just how does it reduce voltage?

If engine runs fine with smoke off, one of 2 issues.  A bad fan motor that can cause noise on 5VDC circuit of board causing all sorts of erratic issues especially with speed control.  Or too large a load from the elements causing issues.  Normally it is the fan and you can test by unplugging the smoke fan and run with smoke on for a short test.  If problem goes away change the smoke fan motor.  G

It was made by MRC, about 2" long with various components and inserted between the power block and the TIU. Reduces the voltage by about 4.  So the track voltage is about 16  throughout the layout.  Less strain on the passenger car lights.  It powers only the track and all my other locos work fine.  Guess I'll try without it but won't be able to for a while because the layout is in a museum in another city (now closed for the season) and will have to wait till I can get there for another work day.  MTH manual says best connection is from a power block.  One additional note the engine does not slow down with smoke in conventional mode.

I'll give disconnecting the fan motor a try. Would hate to have to send it in for repair but at least it's still under warranty.

Correction.  The voltage reduction strip connects the hot wire from the TIU to the terminal block with the feeder wires.

Can you exchange a PS3 fan motor with one from a PS2?  Are they all the same?

Yes, the smoke fan motors are all the same for PS3, PS2, and even PS1.

Thanks.  I have an old switcher the motherboard burned out so it's more or less background scenery and I'm using the motor for something else and the smoke unit is good.

1. Well it turned out to be voltage.  I hadn't checked with a locomotive analysis for a while and apparently this ps3 required a bit more juice than my others and was surprised at the 8v reading in the problem areas.  Additional jumpers took care of it.