MPC Era Diesel Horns

This is a heads up for some of you guys with older engines with the electronic horn installed. Many of these old engines have the circuit board mounted on an adhesive foam pad and I have found more often than not, the foam has turned to dust. This will allow the circuit board to contact the metal frame and short out resulting in a fried board. So if you have one of these and are thinking of running it, it might be a good idea to remove the shell and check it prior to powering it up. Some new foam or sticky back velcro will do the trick on insulating it from the frame. The circuit boards are still available from some parts vendors but it is probably a limited resource. Of course there is always the option of upgrading to a new rail sounds board.

 

 

'Still in Training'

Tom

Charlotte

Original Post

They must have used the same stuff as the old SOS boards used, I've found plenty of those rattling around in the tender.

I have one of those old horn kits if anyone wants it.  Never installed (or even unwrapped because I was underwhelmed by the first one installed back in the mid-80's), includes circuit board, speaker and wired pickup roller (the separate adhesive foam pad is not quite dust as tontee described but not in usable condition). 

 

Update:  horn kit has been claimed.

Originally Posted by hobby-go-lucky:

I have one of those old horn kits if anyone wants it.  Never installed (or even unwrapped because I was underwhelmed by the first one installed back in the mid-80's), includes circuit board, speaker and wired pickup roller (the separate adhesive foam pad is not quite dust as tontee described but not in usable condition). 

I might be interested.  smith25@classicnet.net

Hi Chuck, Half way makes it beep every time but it still sounds very distorted. Changing the wires is a tough one. I'm using all four throttles and have a bus bar on across the commons. Maybe the horn board itself?? Thanks for the help. 

Tomco posted:

Hi Chuck, Half way makes it beep every time but it still sounds very distorted. Changing the wires is a tough one. I'm using all four throttles and have a bus bar on across the commons. Maybe the horn board itself?? Thanks for the help. 

If the sound is distorted you need a new speaker. 

Wow, thanks everyone! I always wanted to add a separate horn button to my layout. Looks like it's gonna happen asap.

 ---Does anyone know the Lionel or MTH # for it and suggest a replacement speaker?   I'll print and follow the button schematic.

How does an engine differentiate between bell and horn button? 

Amherst train show is coming up in a few weeks at the Big E in Massachusetts. 

Thanks again. Tom

Tomco posted:

5906, got it. Thanks Rob. What ohms and wattage speaker should I look for? I've read several on this forum. 16ohm, 8ohm, 5 volt, 3 volt. I probably should pull the shell off and see what's on the OEM speaker. Thought??

The speaker is probably fine. You just need a better controller.

Test the speaker by briefly connecting a "D" cell battery in series with the power to the center rail. In one direction, the horn will sound(here is a diagram with a momentary switch in the circuit):

D Cell Horn

in the other, the bell if it had it:

D Cell Bell

Rob

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TOMCO,

The horn and bell are activated by a DC voltage added to the track by the Activation Buttons. The horn blows with one polarity, and the bell rings with the opposite polarity. Depending how you wire the button, you can get either polarity. You need two Buttons to get both polarities available.

 

Larry

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