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Hi all,

I am new to 2-rail DC and am trying to get my first loop running. I bought a used MRC Control Master 20 for this, but that has proved to not work as of yet (I believe the handheld is not communicating with the base). My current 3-rail setup has a Lionel ZW running to a fuze box (see Backshop video), followed by a DCS system and the track. Can I install a bridge rectifier after the DCS system and use the DCS remote to vary the AC input and, in turn, to vary the voltage to the track? What bridge rectifier should I use for this? Someone on another thread recommended using 10 amp ones, will any of the ones on Amazon work?

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I have a couple of the Control Master 20 for running my DC 2 rail stuff. This is a great power pack for this. Before you look at other options check out a couple of things on the 20; Check the little tabs that make contact when the hand held controller is plugged in. Are all the tabs straight and clean and the receiving tabs are they all clean and straight. They all need to make good contact for it to work. Make sure the momentum is  turned off and the power switch on the back turned on. Try it again not connected to the track does the Green light on back come on at all when you turn the speed dial up? Use a meter or light bulb to check if you are getting power from any of the out puts on the back. You might contact MRC to see if they might be able to fix it for you. There is a circuit breaker on this if there is a short it takes a little while to come back on if there has been a short.

The control Master 20 is excellent.   I use a lot of them.   They are easily serviced if not functioning by an electronic repair service.  The tamper proof screws can easily be removed by using a rotary tool to slice a straight screw driver slot in the head of the tamper proof screw and replace it with a conventional sheet metal screw before taking it to a service center.  Use a short sheet metal screw, some of The locations of The screws can be close To AW NUTS!!!

MRC formerly had Doug, an excellent CM 20 service person but since he left the new folks are rather rude they will not service earlier power packs and only want to sell you their latest, greatest , $$$$$ power pack.  They even told me the earlier packs are not repairable which is flat out false information.

The hand held units can go bad.  I find them on 0 scale yard sale.  The CM-20 pack series with a fan take a different hand held than the CM-20 packs without the fan.

With so many folks desiring the magic of digital control these MRC power packs and hand held controllers can be picked up for minimal cost.   Conventional control is still a strong 0 scale 2 rail power.

The MRC 6200 power pack and the 9000 and 9500 are also great 0 scale power packs.  Again, minimal cost.

If you are using MTH 2 rail Proto Sound locomotives you can simply use your existing DCS system.

If conventional control of 2 rail Proto Sound locomotives is desired in addition to non PS locomotives I would suggest to use a d.p.d.t. toggle to switch back and forth between the CM-20 and the Z-1000 for conventional power.    Conventional Proto Sound works best with a MTH Z-1000 in my world.

I have pairs of CM-20 and Z-1000 set ups through out my RR.  I can walk around the layout and use local panels to control a train in that town. 

Thank you for the responses. I will have to look into opening it up. When I was initially testing it with a multimeter, it did not seem to rise in voltage at all when I would turn the dial. Similarly, the green led did not seem to light at all. The 16v AC terminal however is working perfectly, so I know the whole thing isn't dead. Also, mine doesn't have a setting for O. It only has G and HO/N as the two modes.

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