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Hello Folks,

I'm trying to identify this SW-9 MTH Rail King switcher. I think it is possibly #30-2148-0, but it appears there are multiple iterations of this model, with different versions of ProtoSound (PS2/PS3?). I have attached pictures with the shell removed, can you give me any clues as to it's heritage?

I need to troubleshoot this unit, as it appears to be completely dead. Using traditional transformer power (not DCS), I get no lights, no sound, no movement, nothing. The unit is in excellent condition, wheels and contacts are all immaculate. Any ideas?

Thanks in advance!

20240223_07390420240223_073924WP 601

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Last edited by FortyFivePalms
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It's  DCRU with digital horn board- meaning it is NOT PS1, does NOT have prime mover sounds.

Again NOT railsounds, also not protosound1

At best you have transformer controlled horn- so just applying power you would not get any sounds.

I would think the headlight was directly off of track power? This implies you simply are not getting track power in theory.

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  • mceclip0

In case that wasn't dead clear, what I was saying is that if the headlight is a 14-18V bulb, it's not powered "through" the board in any way. You simply have wires coming from each motor truck assembly with frame(wheels) and middle rail pickup roller, and then a junction of wires often under a wire nut branching off to the board, but also directly to the headlight.

So I would check the bulb, and then if the bulb is good- then it should be indicating the engine is getting power. In my experience, these DCRU engines are some of the longest lasting pretty darn reliable engines. Now granted, the horn board might fail, but that does not affect movement or function of the DCRU.

In case that wasn't dead clear, what I was saying is that if the headlight is a 14-18V bulb, it's not powered "through" the board in any way. You simply have wires coming from each motor truck assembly with frame(wheels) and middle rail pickup roller, and then a junction of wires often under a wire nut branching off to the board, but also directly to the headlight.

So I would check the bulb, and then if the bulb is good- then it should be indicating the engine is getting power. In my experience, these DCRU engines are some of the longest lasting pretty darn reliable engines. Now granted, the horn board might fail, but that does not affect movement or function of the DCRU.

Excellent point. The bulb itself is good, but still no light when installed in the socket with full power to the track. It would seem to indicate something simple (I hope). I will de-construct further later this evening.

Ken, I have an SW-9 of the same vintage. Not PS1, 2 or 3. If it were PS2 or 3 you would have black and white stripes on one of the motor flywheels for the tach reader. The incandescent headlight is also a giveaway that this is a very early MTH engine. When mine worked properly, it would run on conventional and hum around the track without sound. If you pushed the horn button you would get this awful squawk otherwise it was smooth and quiet. Then one day it died. It just sat there and would not respond to power. At that time I had moved on to PS2, PS3 and DCS so I just put it on the shelf and left it. Like Vernon says it's DCRU and you should be able to find some kind of replacement. But first I would poke around and see if there isn't a broken wire or some other easy fix.

@Scott J posted:

Ken, I have an SW-9 of the same vintage. Not PS1, 2 or 3. If it were PS2 or 3 you would have black and white stripes on one of the motor flywheels for the tach reader. The incandescent headlight is also a giveaway that this is a very early MTH engine. When mine worked properly, it would run on conventional and hum around the track without sound. If you pushed the horn button you would get this awful squawk otherwise it was smooth and quiet. Then one day it died. It just sat there and would not respond to power. At that time I had moved on to PS2, PS3 and DCS so I just put it on the shelf and left it. Like Vernon says it's DCRU and you should be able to find some kind of replacement. But first I would poke around and see if there isn't a broken wire or some other easy fix.

Turns out it was - or will be - an easy fix, as long as I can find the necessary replacement parts.

What I found was the pickup roller insulators on both trucks were melted and misshapen, and that somehow led to wires on both - BOTH! - pickups going open. (Of greater concern, perhaps, is what caused these thing to melt in the first place). When I bypass the pickups and power directly from the center rail - Presto! Works like a champ.

Last edited by OGR CEO-PUBLISHER

Simple answer "why" "the pickup roller insulators on both trucks were melted and misshapen, and that somehow led to wires on both - BOTH! - pickups going open."

#1 the previous user had no circuit breaker, fuse, or other current limiter in the wiring to the track from their transformer.

#2 A simple derailment where one truck is on the track normal, and the other is derailed and the pickup roller is touching outside rail. This makes a short roller to roller across the wiring.

#3 Another short could be where a section of track is isolated, and the engine crosses with one pickup in one district, and the other roller in the other district, and there is a voltage difference and massive current- example out of phase transformers

Turns out it was - or will be - an easy fix, as long as I can find the necessary replacement parts.

What I found was the pickup roller insulators on both trucks were melted and misshapen, and that somehow led to wires on both - BOTH! - pickups going open. (Of greater concern, perhaps, is what caused these thing to melt in the first place). When I bypass the pickups and power directly from the center rail - Presto! Works like a champ.

Ken- sent you a PM with the part #'s you should need.

Bob

***UPDATE***

I replaced the melted insulators on both trucks and the engine now runs like new! Many thanks to everyone who helped me here, much obliged!

I'm very impressed with what I see in this engine, and thus I'm going to look into RailKing diesels with PS2. I already have a DCS operating system, so I'll start with a fully operational engine to familiarize myself with it. And then maybe take a swing at a fixer-upper.

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