MTH SD-40-2 Coupler Mis-fire

 When it opens do you here it snap electrically?

They have power running to them so if it sees the chassis ground, I believe it will fire. I would fix that right away and not run it until you do.

You could post on the DCS forum.

Don't run it, it sounds like you have a short in the wiring!  Live power is on the coupler all the time, and the return is switched to operate the coupler.  However, NOTHING in PS/2 is common to the frame, so you are risking damage to the boards.

Gentlemen

Thanks for your prompt reply.

The engine is being towed into the repair shop as we speak.

Blue tags all around. Lock outs are padlocked.

We won''t get a chance to look at it until after this weekend.

Once the problem is found I will publish our findings on the bulletin board.

Have a great Fathers Day!

Just out of curiosity what are the coupler voltages readings across the 2 pins at the board unfired and fired?

Willygee

I won't be able to get into it until sometime next week.

Hopefully its nothing more than a pinched wire.

Once apart I'll try to get those readings for you.

I'll try.

thank you...i may be morphing in a spare remote coupler to a 2 rail premier GP35. There is an empty cplr fr and rear conn on in the loco and i want to make sure my DCS commands the couplers.

 I would use a MTH coupler if you are talking about a three rail protocoupler. In two rail, I have used the Atlas ones and they do work.

 You may want to think about what the coupler draws from the board, not just the op voltage, if you don't know. I would post the brand and type of coupler on the DCS post for compatibility.