I recently purchase a MTH search light car and I found that it does not light or operate when I run trains in DCS mode. Does anyone here have a fix for that. I thought that adding a rectifier might work but the ones I have are quite large. Any suggestions?

Original Post

None of the searchlight cars that MTH sells have any recognition of DCS on the rails, so there's something else at play here.

It operates fine in conventional mode with out a problem. This is the second car I have encountered. The first was a caboose that wouldn't light in DCS. The lights were all good. I converted it to LED lighting and now there is no problem. My PW search light car never operated in DCS mode either so it has me stumped. Every single lighted car I have works except these 3 the lights don't even go on.

That's one I'd have to see to believe it's anything to do with DCS.  There's nothing in that car that even knows the DCS signal exists.

If you're putting full (~22V) voltage to the track under DCS, is it possible that the car has some kind of protection circuitry that prevents the light from turning on ? 

I have one of these from the 1990s; it had a switched vibrotor coil to rotate the light, and an incandescent bulb which is extremely bright in a typical command control environment.  Yours is a 2014 model.  Since  many folks run command control, MTH may have added some kind of voltage regulator.  I would expect this to be true if the searchlight were lit with LEDs, however the MTH product photo still shows an incandescent bulb.

If possible lower the track voltage a little and try again.  DCS should work fine with 18V AC on the rails.

Creep, coast, and pull.  We're not talking about cold fusion here.

RRAddict posted:

It operates fine in conventional mode with out a problem.

If your conventional set-up is handy, put engine in neutral and slowly raise track voltage to 18V or whatever.  

Or, lower the DCS track voltage whether by using a TIU variable channel or lowering the TIU Fixed Input voltage if you have a variable transformer.  For this experiment, DCS will operate fine even at ~12V AC.

I like Ted's theory on something voltage related.  After all, when you are not actively sending a DCS command, the DCS track voltage looks like a conventional track voltage signal.

RRAddict posted:

I have 15 volts going to the track and I don't get a blip or flicker. When conventional power is applied it works as it should. I am still stumped.

Me too!

There have got to be some kind of electronic components between the pickup rollers and the bulb.  Was this true of the caboose?  I'm not sure if MTH has begun using 24-volt bulbs, etc.  But if you're going to run it in a command environment, voltage-regulated LEDs might not be a bad way to go.

Creep, coast, and pull.  We're not talking about cold fusion here.

RRAddict posted:

I have the older car and I have raise the voltage to 16 volts and it operated as it should. I have only 16 volts feeding into the track.

RRAddict posted:

I have 15 volts going to the track and I don't get a blip or flicker. When conventional power is applied it works as it should. I am still stumped.

So to summarize.  16V in conventional works.  15V (or higher) in DCS mode does NOT work.

What are the exact transformers you're using in conventional and DCS?

RRAddict posted:

I am thinking of converting the power going to the car to DC and see if that does anything, any idea what may happen?

If it's the vibrator/buzzing mechanism that spins the searchlight lens, then DC will just generate a lot of heat with no motion.  But as part of this grand science project, it would be interesting to see if the light comes on!

To add to Stan and the others on this twilight zone mystery, (and not knowing the transformers), seems a good idea to take and post pictures of pick ups, wiring, etc. The secret must be in your statement that you converted to led lighting.

Hokie 71

Chief of Operations, Free Union, Blacksburg, and Albemarle Railroad (FUBAR)

I am using a Z 1000 but I did not convert it to LED, I was going to convert the power to DC. Conventional power comes from a Lionel ZW 275 and the car has no problem. There is no special wiring and everything else works as it should. My PW Searchlight car is in the same boat, doesn't function under DCS but fine in conventional. I have power going to the TIU and out to the track, it's a small layout and nothing fancy like an AIU connected. I will do the DC conversion for tonight.

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