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I have a SW7. Lionel 6-85024. The couplers front and rear stopped working. The sound still comes out of the speaker. I pulled the cab off and checked the couplers on the bench and they open at around 6 volts. I then checked the board out put and it showing around 5.5 volts. Put it back together and neither still do not open. What am I missing here?

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Yes sir I have tried that also. Changed the number and didn’t change anything. I wasn’t sure how many volts are to come off the RMC board. I know on the bench it takes under 6 for the coupler to open and very quite. Didn’t go past 6 volts on the bench. But the board is only pushing 5.5 volts off the board. Wasn’t sure if that’s where the issue might be and if there’s anyway to turn that higher?

Well anyone with more experience can correct me if I’m wrong but I believe the RCMC puts out DC voltage to the couplers not AC. And I would definitely measure the voltage with the load in the circuit. Without the load you may read some “capacitive” voltage that when the load is there disappears and what could be going on is that I think the RCMC uses FETs for the couplers and they might’ve failed where you may see some voltage but can’t handle the current and then the voltage goes away.



That’s my first thought. Weather or not my theory is correct or not I don’t know but that’s where I would start

Thanks for answers. I will tear it back down tonight and measure it dc with a load. So the question still remains, what should it be putting out? And if it is low, what can be replaced short of installing a new $120 complete board. When I talked to Lionel yesterday they couldn’t answer that question. There response was to take all the boards  out, reassemble everything and make sure all connections are tight going back together. They didn’t think there was an issue with the boards other than something was not making a good connection.

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