PS2 loss of speed control.

Remove shell and make sure no wires got pinched.  Inspect tach board at stripped flywheel.  Positioned correctly and no wires broken off the board.  Should have 3 wires going to it.  Gray, Orange and Blue.  Gap less then a dime centered on the flywheel.  G

Okay, I will check that this afternoon.  Before I left for work this morning I took the shell off and tried it...same results.  It also did the same thing in reverse.  When it starts moving, it accelerates to max speed, well I stop it before it gets going too fast.  God only knows how fast it will go.

You can always lower track input voltage to around 12 even in command mode.  Helps limit the max run away speed.   Did you try a factory reset, just in case you turned speed control off.  G

No on factory reset, yet.  What is the procedure for a factory reset?

Menu/Advanced/ reset engine/ factory reset.... Engine will be deleted from the remote.  It  should add back at the lowest available ID (spot) on the remote.

How was the spacing between timing tape and reader?

Ill be checking that soon as I get home.

It sounds like to me that the tach paper is damaged or missing.

Scott Smith

...or the gap is off or the tach reader damaged, or one of the tach wires broken between reader and board. 

Clint, you ought to post the MTH model number.

The tach paper is intact and looks good.  The reader could be too close or too far away.  ill be home in a few hours, the shell is still off so easy check.  the model number is:  MTH 20-2772-1

On a Lionel engine I have the motor flywheel with the tach strip was actually loose. If there is a set screw for your MTH engine you may want to check that as well.

Scott T Johnson posted:

On a Lionel engine I have the motor flywheel with the tach strip was actually loose. If there is a set screw for your MTH engine you may want to check that as well.

Not MTH Diesel.  FW pressed on. G

Over ten years ago, I had a pressed-on MTH flywheel come loose and result in this happening.  Worth checking.

Well I did a factory reset and it made no difference.  I took some pics see if y'all can spot a problem...

I appreciate any and all help.  This is my favorite locomotive.

Here is the info on the box...

You need to get real up-close-and-personal to inspect the 3 tach wires under a bright light.  Maybe use a toothpick or the like to poke around the connections at the PS2 board itself and on the tach board with the level of resolution illustrated in the above photos (nothing wrong with the wiring in these photos).  There may be 1 strand of wire that somehow worked itself loose and is bridging over to the adjacent connection.

As GGG suggested earlier follow the wires looking for a pinched connection or whatever.

If you have a digital meter and have a somewhat steady hand, there are some voltage measurements you can take.  Seems to depend on whether you'd just as soon send it in for repair...or if you're the DIY type and would prefer to work on it yourself, say buying/replacing the tach board or whatever.

It's hard to tell from the pic  the distance from the timing tape & reader, If it's about the thickness of a dime should be  ok . Anything larger that an 1/8" and you'll  have the same type of problem.

Did  you put the  battery back in? and is it good?  Changing  features and having them stick  requires a good battery.

 Also try  a  Feature rest    Menu/advanced /reset engine/  Feature reset.

Re-seat the plug that the center rail. chassis ground and  tack  reader plug into the main board

Clean Tack reader if possible (Q Tip or something thinner)

I can't see anything out of the ordinary on the pics.  No strays strands of motor lead  wire touching the motor casing ??

Will do...stay tuned.

Ok under a magnifying glass the wires look great.

Strange thing, I did not remove the battery and I really didn't mess around with anything under the shell.

WAIT A MINUTE....LOOK WHAT I FOUND AND THIS WIRE GOES TO THE TACH READER...this could be it!!!

Nothing beats a careful inspection.

Good job... Hope that's it, Is the wire completely  broken in two  or just need a little tape.

Well the wire was not broken, I taped it up.  I did a feature reset, no effect.  This is baffling.  Everything else works perfectly, sound, smoke, start up, shut down, forward & reverse, all functions work normally.  Im stumped! Is there anything else I can do?  I do have a digital meter.  I can do most anything, but this is tough.  This is costing me big money, that locomotive needs to be pulling a fully loaded freight train.  

Mr Union Pacific posted:

This is costing me big money, that locomotive needs to be pulling a fully loaded freight train.  

That's pretty funny.

Meanwhile, back at the ranch... something ripped off that insulation and it stands to reason that it would have been something sharp and probably metallic (like a screw) when re-assembling the chassis?  If it was metallic it likely shorted the blue wire to the chassis.  Who knows what havoc that might have caused to the electronics possibly taking out the sensor chip on the tach board or maybe something on the PS2 main board?

There have been previous threads on measuring voltages on the 3 wires.  I'm pretty sure you can find those threads pretty easily.  They'll also tell you to pop out the tach board and confirm it's putting out IR energy by looking at it with a digital camera.  Then you can measure the tach voltage going up and down as you rotate the white/black stripes across the reader.  If you get good white/black readings then the next suspect is a speed sensor IC chip on the PS2 board which is only a 50 cent part but is difficult to change as it's a surface mount chip.  Again, there have been threads on changing this speed sensor chip too.

Welp, that sounds good. Im going to do a little search on that and see what I find.  Thanks!

I'd start by replacing the tach reader.  Good chance either it or U12 on the power supply board was damaged when that got grounded to the frame.  If the tach reader doesn't do it, I'd suggest you send the boards to GGG and let him fix them.

I can replace the tach reader, but where would I purchase one?  Might the battery have anything to do with it?

You could buy from MTH directly, and pay a large shipping fee, or techs who post on the forum would probably be willing to sell one.  I doubt that the battery would have anything to do with it.

Responded to email.  Pinching blue to chassis is not good.  Can be both speed amp and tach reader damaged.  Needs to be tested.  G

Well looks like ill be sending it in to a tech.

Don't get me wrong, I love the DCS controlled stuff, but there is something to be said for the old postwar locomotives.  These computers and circuit boards are extremely sensitive.   

Clint, if you had a model T, you wouldn't have problems with starter, heater, a/c, transmission.

Excellent point RJR.

Mr Union Pacific posted:

Don't get me wrong, I love the DCS controlled stuff, but there is something to be said for the old postwar locomotives.  These computers and circuit boards are extremely sensitive.   

Yes they are just too sensitive and we have to be really careful and lucky else this type of thing happens. You're not alone but GGG will get you fixed up at a fair  reasonable price.

Yep, I am sending it to him next week.  I am just calling it a learning experience...I should have left well enough alone.  My dad used to needle me about always having the hood up on my truck when I was in high school...he would walk by and say;  "Is something wrong with your truck?"  I would answer; "Nope, I'm just fixin it!" 

Mr Union Pacific posted:

"Nope, I'm just fixin it!" 

OK, now it's "fixed", time to move to the next project!

Technically you are right, "fixing," but being a good ole southern boy, well "fixin" just feels good.  Now I have to go pack up my favorite locomotive for shipping.

Gregg posted:

Mr Union Pacific posted:

Don't get me wrong, I love the DCS controlled stuff, but there is something to be said for the old postwar locomotives.  These computers and circuit boards are extremely sensitive.   

Yes they are just too sensitive and we have to be really careful and lucky else this type of thing happens. You're not alone but GGG will get you fixed up at a fair  reasonable price.

 

Not sure I agree with that completely. I've taken apart and put back together many engines. Some multiple times swapping wires parts and boards along the way. Early on I made mistakes -- like Clint -- and it cost me but I learned from it and have had no problems since. One of the big advantages with MTH engines is that for the most part the shell comes off and goes back on easily (unless it's an Alco S2). The one Legacy engine I tried that with made it clear to me that I was never gonna get that shell off all the way and I was fortunate to do the repair with a partial removal.

My point is if you like to fix things don't be afraid to work on your engines. If it's a big job send it to GGG or get help on the forum. Recently I had a much loved PS2 switcher fail on me (dead). At the same time I had just purchased a used GP-9 on eBay. Mechanically it was good but the shell was trashed. So I posted on the forum: could I swap out the board set? Answer was yes. So I did and the switcher runs like a dream. The rest of the GP-9 is now scrapped out for parts. Including BTW a motor with tach reader attached if I ever need one.