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Damian18

Power Supply Malfunction

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My Chicago Model International 101 MW Blue series Had been working fine for years until this evening. As I was running my train this evening (indoor shelf Layout) The power supply automatically on its own powered up full Throttle for some unknown reason causing the train to derail and short out the tracks. Now I have No DC output But the AC output side works fine... Any Ideas on what could have transpired or does anyone know the technical aspects of this particular unit

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On 10/7/2016 at 6:59 PM, Damian18 said:

My Chicago Model International 101 MW Blue series Had been working fine for years until this evening. As I was running my train this evening (indoor shelf Layout) The power supply automatically on its own powered up full Throttle for some unknown reason causing the train to derail and short out the tracks. Now I have No DC output But the AC output side works fine... Any Ideas on what could have transpired or does anyone know the technical aspects of this particular unit

 

Hello,

I'm not familiar with your particular power supply but I have a Vintage Troller that has done the same thing in the past. If your unit is straight DC output and uses an AC Transformer with a rectifier for conversion to DC. Sometimes these units contain a Triac or Silicon Controlled Rectifier (SCR) to control the  power, the Triac or SCR is probably burned out. These units have three pins. Two pins are for power in and out and the third pin is a gate controlled by a potentiometer. That's for your power level control.

 

When a Variac burns out, they can fail in either of two ways: 1. Go open, so that there is no output, or 2. Go closed so that there is no regulation and the power goes straight through causing full speed operation with no control. This sounds like your problem.

 

I would open up the unit (unplug it first, please. :)) and look for a unit that looks like the picture attached. I don't have any equipment to test them myself, but in my case, I got the number on the case and replaced it with one from Radio Shack. (Sure hope they stay in business...)

 

I still have two of the Troller units that I used for DC control of my former HO Scale layout as they put out something like 2 amps. When I switched to G Scale, I needed more power so I built  a dual 5 amp power pack for two cab operation. The Trollers are now used for bench testing of small components. Both of them have had the Triacs replaced at one time or another after burning out and going wide open.

 

I hope this helps.

triacs-diode-modules-500x500.jpg

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