A replacement pot should work.  10K is the "ohmage".  Some googling indicates to me that the B indicates a linear pot, which would make perfect sense for a train throttle.

To "ohm it out", connect an ohmmeter from one outside post to the opposite one.  The center post is the "wiper" that varies as the pot is turned, but the two end posts should be the total ohms... 10,000.

So, you need a similarly sized Linear 10K pot.

Ed

Not necessarily, there are many types, linear, non linear, carbon, wire wound etc

Take the damaged pot with you to an electronics shop who know what they are talking about.

Dave,

I agree, but I had one apart a while back and it looked like a cheap carbon pot.  I would think that it would be linear so that the amount of variation is consistent across its sweep.

IMHO,

Ed

Eddie, you're probably be right, they are just a cheapy carbon job by the looks.

Dave,

I was in there because I wanted to figure out a way to connect a wired remote to the Z1000.

My thinking is that if I put a Cat 5/6 jack on the outside of the Z-1000, I could connect the pot (3 wires), a bell button and a whistle button (3 wires) with a standard Cat 5 cable connected to a remote pot, and 2 pushbuttons.  It's on my to-do list!

I've already don it for the whistle button so kids can blow the train horn from various locations on my layout.

Ed

 Thanks guys!

I wonder if MTH would sell me the pot and how much$?

I might be off to the guitar store!

Guitar store may have an audio taper... you need linear.

Radio Shack, on the other hand, has this:

10K-Ohm Linear-Taper Potentiometer

 looks like they're in quantity from the East on the bay.

10 of them for a couple of bucks! .99c ea from Thailand.

probably going to be around $15 here right?

Wow that's service!!

Thanks for the source!

My RS always tries to sell me a phone!

Wouldn't the pot have to be a specific mechanical mounting?

Looks like they adapted their board to a generic pot to me. I don't have any access to their service sheets.

Does it look like a PS-1 volume pot?  You probably have a few of those laying around.  Even if it won't fit, you can wire it in to test to see if the pot is bad.  Or do the measurements, I go from center to each end with the knob all the way in one end.  It should read 0 to one end and 10K to the other.  Rotate pot fully and the measurements should switch.  Than check it while rotating.  If it moves from 0 to 10k linearly it is probably ok.  G

 Yeap, it does that fine?

 RE: Z-750..   I can sympathize  with eng-joe. same deal for me. either full on or no voltage.  i replaced the 10k-b pot AND the q2015ls  [regulator?]  no change "still" full on or full off.  do any of our geru's have a clue ?  

This recycled photo from another thread where the topic was how to tap into a Z750 to control it from an Arduino.

Anyway, as og fan's experience suggests, it may not be the pot at all.  The voltage is varied by changing the "firing angle" of a triac (Q2015).  In other words, the output voltage is indirectly varied by the pot and there are many other components in play.  Without further guidance from an MTH tech who has experience repairing the described symptom and volunteering which parts to look at, you'd need to go backwards through the circuit and essentially get lucky.  For example, can you see the trigger pin signal on the triac changing as you turn the pot?  Do you see the voltage on the pot wiper itself changing as you turn the pot?  Etc.

Fortunately you are only poking around an 18VAC triac circuit rather than a, say, 120VAC triac lamp dimmer circuit...

 Thanks for the post Stan. I know enough for two things.

1) I know something about an output triac as I've popped one before and a tech told me that's why 1 of my audio amps failed.

2) that I don't know enough to go any farther!

Looks like I have to send it to someone!! (G?)

 Some weird clues:

As I'm turning the throttle with a PS3 RTR steamer, the horn blows?

The horn and bell seems backwards?

This engine runs fine on my other Z1000 throttle?

I reversed the red and black outputs and the horn and bell button worked normally at first. Then worked intermittent?

I swapped bricks and the throttle still doesn't work right.

I put an older TMCC engine on the track and that one runs better?

Maybe there's some voltage leak past the throttle??

 I'll poke around with it live to see Stan.

No voltage at the pot's terminals

Output voltage jumps sharply as the throttle is turned. Seems to read +10.something right away and then 20+ just after that as the throttle is increased.

 Can U tell me where the TVS is on that picture? and What should it read across it?

If you're trying to fix it for the "intellectual challenge" that's fine, but once you get past a simple pot swap-out, the fact that a new one is only about $35 comes into play.... IMHO.

Ed

 Thanks again Ed.

Yes, I'm considering that. It would be nice to show others if they are experiencing this problem. I thought I've read that the particular Z750 throttle, may have it's own issues? Maybe that was just phasing?

 I should have just bought another new Z1000? or whatever I have for the grandkids. This was a impulse buy. At least the brick works. Electrical parts are cheap. The knowledge to fix them costs the big bucks.

Joe,

I've had great success with the Z750 and Z1000 controllers.  Not a bad one...yet.  I have noticed that not all MTH Z1000 bricks are phased the same, even though they have a one-way only AC plug.

If it's for the kids, and with DCS engines, you might consider a DCS commander for and use the Z1000 brick.  If running conventional, they used to make an infrared remote that ran conventional trains by infrared remote with a Z1000 brick.  Both on the 'Bay for under $40.

Ed

 Well....this is the way the story goes. I bought the kids the PS3 trainset for Christmas last year. It has the commander already. They burned up the engine which got me mad.

 It seems that they struggle with the concept of the engine taking a while to respond to commands like slow down, when it's going full speed and jumping the tracks. So, their mother told them to unplug the set when the engine is going to fast. They've done that so many times, they wore out the receptacle. I went over to see why the train wouldn't run, and found out they were doing this.

 Jump ahead past an even longer tail, and the engine burned up. I had G fix it. We agreed that they don't know how to run it so they're not getting it back until they're older. I'm trying to solve things so I bought them a cheap Peep and figured a normal throttle. Now, the throttle doesn't work! Urrggg.

 I teach them how to run trains. I forget to train the parents!

Ed is correct, I asked MTH and now all the controllers are the Z-1000 style, regardless of the brick.  May be cheapest to just get a used one off the bay or list.   G

You got to know when to hold 'em, know when to fold 'em, know when to walk away, know when to run...

Given the modest cost of a replacement and without a list of "usual suspects" from someone who has worked on these these, perhaps it's time to fold 'em.

If you just want to mess with it for entertainment, consider these circuits are about timing of the firing/trigger pulse to the triac relative to the 60 Hz zero crossings.  You'd probably need an oscilloscope.  These circuits generally have an opto-coupler to electrically isolate the timing circuits from the AC control (the triac).  The part above the pot labeled MOC3010 in the photo is most certainly it.  That said, when you talk about DC leakage, you're really talking about the skewing of pulses going across the opto-coupler.  If this makes absolutely no sense, don't pass go, don't collect 200.

Separately, if you have a lower voltage transformer/brick for your PS3 RTR set this is one way to limit the top speed of the engine for the grandkids. The DCS remote commander will run fine even at, say, 12V.  I don't know how fast the train will go at 12V or whatever but might be something to try.

 Yes, the set came with the commander and a wall wart for power. That little engine was doing a hundred when on #31 curves that come with the set. For some reason, when I'm in the room, they play nice and slow with it. When they're alone, that engine's going full speed until someone yells at them.

 I think the easiest thing is to give them something that's built like a Tonka truck and can take a beating. I've shut off the smoke because they didn't have fluid. When I return the smoke is back on full, for example. Their dad says he found some oil in the garage that works. I give up. I can teach the kids. I can't get past the parents.

 The fact that I bought them a train and it does not work, means I have to fix it! I wonder sometimes if they've sat on the thing just to break it for me. My girl had the best idea, take it away 'til they're older. Their parents tell them to ask me to build a whole train layout in the basement for them. I can't even keep the loop running on the floor!!

Don't mention "used" right now!

I had gotten them a set that had the old remote for kids. We had to keep it at our house because they were too small. That didn't work out.

 "Why doesn't Our remote have all the buttons like your's does?"

So the set for Christmas was to fix that.

Let's not leave out the spare engine I just bought. New wide 072 curves for high speed running. New straights and switches so they can have a layout like Papa Joe has.

 Urrrgggg. Used? Sure. "will it be bullet proof!"