k line reverse board repair

This is more of a @gunrunnerjohn question, but off the top of my head, it sounds like one or more bad diodes in the rectifier bridge.  Might want to check them first...

https://www.wellpcb.com/How-to-test-a-diodet.html

Hope this helps! 

Mitch

Diodes or a bridge are at the input side of the board. Typically its the output devices to the motor that fail either triacs or transistors. You can apply voltage to the board and just feel whats getting hot, then check them with an ohmmeter to verify if they are shorted. You may have to hook up a motor to do this test. K-Line E units do tend to fail though.

Pete

It's probably more of a question of is it worth it.  By the time you pay shipping two ways and for the repair, you'll have significant money tied up in the repair.  I'm guessing there are a number of people that might have a board like that in their parts box that you could buy for less than trying to fix this one.

Thanks

Two of the power transisters are blown. I am going to replace all four. During shipping of the locomotive to me (at time of purchase), the weight stack had loosened and may have contacted (and shorted) the board. Either that or someone tried to run the locomotive without any lubrication. Hard to say. It works well with the new board but I wanted to have a spare and to learn a bit about the electronics as well.

Thanks again.

I have had better luck using Williams E unit boards to replace the K-Line ones. I have a few from TMCC upgrades. They use relays for power handling and have a better mean time between failure.

Pete

I replaced all 4 transistors but it still does not work. Back to the parts bin!

@Victor Bertolina posted:

I replaced all 4 transistors but it still does not work. Back to the parts bin!

I had the same experience a couple years ago.  I can only assume that something caused the transistors to croak and I didn't get that.  Likely it would be the rectifier.