railking remote lock-on item no. 50-1013.

What usually fails on those is the triac controlling the track power, they can be replaced.

sounds good, if only I knew what it looks kike and location on board, also where to but one or have some fix it for me. I am getting close to 92 and can not do what I usually could

now I know what it looks like, I have to find one, anyone know where?

This OGR thread might be related.  If your symptoms are similar there are 2 transistors that behave like the iconic "triac" used to control the AC track voltage.

The IRFZ34 is (was) a widely used part and is readily available.  Example from Amazon shown above.  Given USPS package postage rates start at about $5, while you obviously don't need 10 pieces, I'm not sure you'll find a much better deal shipped to your door.  Well, I did look on eBay and there are some U.S. sellers where you might save a buck or so...

Thank you, I will try them and get back to you, again thanks, every idea is worth a try

Since you'll have 10 pieces, I suggest you just replace both transistors.  Yes, we could go into troubleshooting mode using a meter to diagnose if it's just 1 of the 2 that failed or whatever, but why bother.

I just checked on eBay and it appears if you bide your time you can buy a 50-1013 working unit for around $30 (or less).  But bidding/buying on eBay is not for everyone.  I get that.

So if going the DIY route, when you get the parts, if it seems too daunting a task, I will replace them for you.  All I'd ask is you pay for shipping.  My understanding is this remote-control lockon is no longer available (at least the MTH site availability page suggests that).  So if this is what's stopping your from enjoying your trains at age 92 (wow!) I might be able to help...

@stan2004 posted:

So if going the DIY route, when you get the parts, if it seems too daunting a task, I will replace them for you.  All I'd ask is you pay for shipping.  My understanding is this remote-control lockon is no longer available (at least the MTH site availability page suggests that).  So if this is what's stopping your from enjoying your trains at age 92 (wow!) I might be able to help...

Classy offer Stan.

I replaced both units, but guess what? It still will not work. Thanks Gunrunnerjohn anyway, we tried. I guess I will have to to a diffent controller

Well, with the whole unit selling for around $30, it's not price-prohibitive to buy another one.

i HAVE CHECKED AROUND, NO ONE HAS A NEW OR USED ONE. THE ONE I HAVE HAS TOO MANY PROBLEMS. GUESS  I WILL PROBLY GO FOR A SUBSTITUTE CONTROLLER. ANYWAY THANK ALL OF YOU GUYS FOR YOUR CONCERN

Resurrection of this post, funny enough. I just purchased one of these off of eBay.

For those who know more about this circuit, I'd like to learn a bit more.

It was working great until a wheel short across the track (which tripped the MTH Z750 4 amp breaker) and then I'm in the same position as alot of these posts.

It acts as a pass through for a full 21V AC to the track.

Those Power FETs (or are they Triacs?) That usually go bad I've seen some datasheets of variations of them be tolerant up to 21-30 Amps...

I'd find it hard to believe that little lock on saw that much, or maybe a less current tolerant part was selected. Either way, any other common points of failure in this device? I have a new one on order, but might want to fix this one.

Does anyone have a schematic?

John & Stan I figured you two might know something 😀

On a side note, I find it a bit odd that this lock-on's over current protection isn't robust enough with a transformer limit it shipped with..

Are these notorious for these failures? I noticed a few posts, but not many.

No, it was not amps that killed the MOSFETS. More likely, you killed the TVS diode. It's voltage spikes generated from the track, train, and wiring inductance and capacitance. Each time you open circuit an inductor after passing current- that creates a several hundred volt spike.

Both FETS are IRFZ34 https://www.vishay.com/docs/91290/91290.pdf

The TVS is a 1.5KE51CA https://www.digikey.com/en/pro...QDEsAVAWgDkAREAXQF8g

Thanks to @stan2004 for this previous post.

@stan2004 posted:

This OGR thread might be related.  If your symptoms are similar there are 2 transistors that behave like the iconic "triac" used to control the AC track voltage.

The IRFZ34 is (was) a widely used part and is readily available.  Example from Amazon shown above.  Given USPS package postage rates start at about $5, while you obviously don't need 10 pieces, I'm not sure you'll find a much better deal shipped to your door.  Well, I did look on eBay and there are some U.S. sellers where you might save a buck or so...

Again, electric train basics. Just the wheels rolling on the track carrying current to something as simple as a light bulb. There are millions of make and break contact events that happen in just rolling a few inches. As soon as we add motors and electronics, now we are adding capacitance and inductance that is experiencing this constant make and break contact.

As a simple proof of concept, take just about any postwar loco and some alligator clips to a simple transformer. Hold the loco in the air and ensure with one hand, you are both touching the 3rd rail pickup and the frame of the loco. Now slowly turn up the transformer. If you can hold on- I'm impressed.

The reason is, you can touch powered track or wire leads of a train transformer easily and not even feel a shock at say 12-14V (as long as not wet and no cuts in your fingers). However, if you have a postwar train on there, and make and break that contact- causing a collapsing magnetic field- and your hand is in parallel- I promise that is going to hurt when that several hundred volt spike hits you.

Now imagine the abuse your controller takes every time you run the train- let alone a derailment.

@Vernon Barry posted:

No, it was not amps that killed the MOSFETS. More likely, you killed the TVS diode. It's voltage spikes generated from the track, train, and wiring inductance and capacitance. Each time you open circuit an inductor after passing current- that creates a several hundred volt spike.

Both FETS are IRFZ34 https://www.vishay.com/docs/91290/91290.pdf

The TVS is a 1.5KE51CA https://www.digikey.com/en/pro...QDEsAVAWgDkAREAXQF8g

Thanks to @stan2004 for this previous post.

Okay, so flyback transient situation, overvolt protection in this case, not over-current.  Brings back memories of EE school , I remember the "Current can't change instanteously in an inductor and voltage cannot change instantaneously in a capacitor" concept.

Thank you for clearing that up!  Looking into this more, there seems to be a key trade-off design between the cross-sectional area of the PN junction of the TVS and tolerance for time exposed to a transient event.  I guess there's only so much energy than can be dissipated as heat before the component can't handle it anymore.  Since this has to fit in a tiny little lock-on, makes sense why there had to be a choice not to go bigger, even though it already seems fairly large.

I am sure they didn't think about having idiots like me overload their device 23 years after it was made.

Thanks for sharing your knowledge!  I am enjoying learning about this.

@Vernon Barry posted:

Again, electric train basics. Just the wheels rolling on the track carrying current to something as simple as a light bulb. There are millions of make and break contact events that happen in just rolling a few inches. As soon as we add motors and electronics, now we are adding capacitance and inductance that is experiencing this constant make and break contact.

As a simple proof of concept, take just about any postwar loco and some alligator clips to a simple transformer. Hold the loco in the air and ensure with one hand, you are both touching the 3rd rail pickup and the frame of the loco. Now slowly turn up the transformer. If you can hold on- I'm impressed.

The reason is, you can touch powered track or wire leads of a train transformer easily and not even feel a shock at say 12-14V (as long as not wet and no cuts in your fingers). However, if you have a postwar train on there, and make and break that contact- causing a collapsing magnetic field- and your hand is in parallel- I promise that is going to hurt when that several hundred volt spike hits you.

Now imagine the abuse your controller takes every time you run the train- let alone a derailment.

I think this puts it right into field of view