Hello I would like some advice please on my command 2000 system. I am using a 13.5 v filtered and regulated DC supply that can provide 6 amps under load. When I connect the supply to the Command 2000 and measure the output current without the system being attched to the track I get 8.5 v on my meter. When I connect the system to the track and measure the voltage it drops to 6.5 V. I seem to be able to run one train slowly in both directions and operate the light so I assume the system is working ok. Where and what can I do to find the fault. If I put 2 trains on only one runs the other just jerks slowly on the spot. The engines are Atlas engines and the decoders are mrc. All I had to do was plug them into the PC Board on the train.If I disconnect the MRC system and reconnect my old 12v 2amp supply as normal DC operation the trains run fine. Your assistance is greatly appreaciated.

-- Kevin Jones (kevinj@icon.co.za), October 08, 1998

Answers

Hi, I have the commmand 2000 and I use 18.5 volts ac to feed the controller. The voltage you are using is too low for the controller. If you look in the manual I think it says the input voltage should be 18.5 volts ac or dc. One of the people I know who builds power supplies for command units uses 18.5 volt supplies. Hope this helps. Gordon

-- gordon p hulford (ghulford@nanaimo.ark.com), October 09, 1998.

Kevin,

The input voltage you are using a little on the low side, 13.5 volts for DCC.

Check your manual or with the manufacturer. I think you will find a higher voltage recommended. Most system will be in the area of 16 to 18 volts for input.

Also note, that even though you are using a DC input voltage, the voltage on the rails is a square wave AC voltage. You will not be able to use a DC meter setting to read the voltage. Because of the square wave form, even a AC True RMS meter will only get you close on the readings.

Here is why you need a higher voltage. There is a approx 2 volt drop from the boosters input to output. Thus if you have 16 volts input, you will have a 14 volt output on the rails. Now there is another approx 2 volt drop in the decoder. So with 14 volts on the rail, the Loco motor will see 12 volts.

Don

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Remember Always Have Fun and Enjoy!, Don Crano Akron, Oh NMRA #096211 mailto:donc@sssnet.com Visit Model Railroading with DCC at: http://pages.sssnet.com/donc/

-- Don Crano (donc@sssnet.com), October 11, 1998.