I have 4 CM20 units running my layout for many years without issue to date. Now to your issue.......Go to MRC.com website....select MRC....go to drop downs for customer resources....select power supplies. There I found the user manual and a pin out diagram for the cable and hand held controller. Per your problem description, I would look closely at the pins/wires in the socket. They could be bent or broken off. If they look good then meter out the actual cable pin to pin for an OPEN. They use a standard business phone cable and jacks which amounts to 6 pins with 1 and 6 not being used. Since this is a hard failure, visual inspection or meter readings should point to failure rather quickly. Good luck,post your findings and the fix.
I agree with Mike, as it sounds more like a problem with the 'phone cord.
Major sections of my layout semi-shut down last year, with trains running extremely slowly in some areas and not at all in other places. There were some areas unaffected, too. Nothing made any sense to me, as it's wired, common rail, with only two feeders from my Control Master 20.
After spending several days, over the course of a couple of weeks, under the layout, I accidently stumbled onto the problem: the plug-in on the walk-around throttle had lost the clip that keeps it plugged into the 'phone jacks on the layout's fascia, with the result being only partial contact.
I simply cut it off and clipped on a new one - problems disappeared!
Wayne
Sounds like you broke a wire in the phone plug style cord that goes between the base unit and the hand held. With MRC in limbo as they transition to the new owners, you might try ebay for a replacement handheld that includes the cord. I do not know of anybody that works on that type of transformer. Old Lionel stuff yes, but not the newer stuff. Unfortunatly most of those were made as a "throw away" design. We had a few of those controlmaster 20's give up at the local club, so I put in the older copper metal case transfomers, along with the copper colored metal case handheld controlers that were offered years ago. Those held up much better and were easier to fix when things broke. Mike
Silly NT's, I have Asperger's Syndrome
It's me again with power-pack problems. Does anyone on the forum know of anyone that works on powerpacks? Reason I ask is that my Controlmaster 20 is acting up. I thought it might have given up the ghost, but I don't think so. I get a power light, but no voltage control. It sounds as if it might be a rheostat problem more than anything. What happened is that I tripped over the walkaround control cord extension (hey, I'm an old man, lol!) and jerked it in the connection. I've tried replacing it with a new MRC9950, but it just isn't the same and the walkaround only extends for five feet. At any rate, if any one knows any repairmen, especially in the California area, I'd sure appreciate a reference.
Tom
Tom View my layout photos! http://s299.photobucket.com/albums/mm310/TWhite-014/Rio%20Grande%20Yuba%20River%20Sub One can NEVER have too many Articulateds!