# Operating Coal Tower - RailKing/MTH



## KimmieMcK (Jul 17, 2012)

I'm having an issue with the crane function... it will only move in one direction - up. I cannot get it to move down... Through process of elimination, I think it's a diode in the controller... I'd like to check all the wiring before I do anything else, just in case it happens to be wiring, not a diode. Does anyone know where I might find a wiring diagram of the coal tower and hopefully its controller?


----------



## gunrunnerjohn (Nov 10, 2010)

MTH isn't very good about posting schematics, and apparently this item is no exception. I'd just trace the wires out and see if you find anything. You can also test the diodes with a multi-meter to see if they're good.


----------



## Big Ed (Jun 16, 2009)

KimmieMcK said:


> I'm having an issue with the crane function... it will only move in one direction - up. I cannot get it to move down... Through process of elimination, I think it's a diode in the controller... I'd like to check all the wiring before I do anything else, just in case it happens to be wiring, not a diode. Does anyone know where I might find a wiring diagram of the coal tower and hopefully its controller?



I found a service review here,
http://www.mth-railking.com/service...ng/Accessory/coaling_tower/coaling_tower.html






I also found this, will this help any?


----------



## KimmieMcK (Jul 17, 2012)

Thank you so much! I'll see if the diagram helps, and I'll test the diode with multi-meter


----------



## KimmieMcK (Jul 17, 2012)

Thanks again for the help. I've diagnosed the issue as a diode in the controller. Now I just have to wait for a new one (diode or board or whole wiring harness) from MTH. We'll just wait and see what they send, I guess! Thank you, thank you!


----------



## Big Ed (Jun 16, 2009)

KimmieMcK said:


> Thanks again for the help. I've diagnosed the issue as a diode in the controller. Now I just have to wait for a new one (diode or board or whole wiring harness) from MTH. We'll just wait and see what they send, I guess! Thank you, thank you!


Is it fairly new?
They will send you the new piece free?

The diagram does have a radio shack part number for the diode.


----------



## gunrunnerjohn (Nov 10, 2010)

I wouldn't pay much for a bum diode, it should be pretty easy to replace.


----------



## KimmieMcK (Jul 17, 2012)

It's fairly new, but not new enough for them to send me a new piece for free... 

I've never replaced a diode before, but it seems like I would just have to unsolder the old one and then solder in the new one, is that correct? (Making sure to place it in the right direction, of course). It seems easy enough, but I don't want to assume anything. We all know what that can do at times! LOL! 

I'd much rather pay the $1.29 and replace the diode myself than wait for MTH to figure it out and get it sent to me.


----------



## gunrunnerjohn (Nov 10, 2010)

Yep, if it's a standard through-hole component, it's really as simple as that. Just use either a controlled heat soldering station or a low wattage iron around 20-25 watts to avoid damaging the traces on the PCB.


----------



## KimmieMcK (Jul 17, 2012)

AWESOME! Thanks!!


----------



## gunrunnerjohn (Nov 10, 2010)

Let us know how you make out.


----------



## KimmieMcK (Jul 17, 2012)

It's FIXED!!!! Thank you so much for your help!!! Definitely a cheap, easy fix, and I didn't have to wait for MTH! Wasn't sure about messing with diodes, but it was very easy! THANK YOU!!!


----------



## gunrunnerjohn (Nov 10, 2010)

Glad it all worked out. Now you have to skills to fix all sorts of stuff.


----------



## Big Ed (Jun 16, 2009)

KimmieMcK said:


> It's FIXED!!!! Thank you so much for your help!!! Definitely a cheap, easy fix, and I didn't have to wait for MTH! Wasn't sure about messing with diodes, but it was very easy! THANK YOU!!!



You are now officially our MTH Coaling Tower expert, all questions will be directed your way.:thumbsup:

I wonder what made the diode expire?


----------



## gunrunnerjohn (Nov 10, 2010)

My guess is a short, the diodes are there because the motors are DC and the power is AC to the unit. If you short the motor, or stall it for a time, it may take out the diode.


----------

