June 22, 2011

Trouble with a decoder

Tonight the gremlins descended into my basement and started trouble with the QSI Revolution U decoder installed in the locomotive Whiton. It was working fine up until tonight. Now it will only run in one direction. All other functions seem to be OK, including sound and ops mode programming.

I tried resetting the decoder several times. I can get the decoder to speak back "reset," but resetting does not fix the problem. Note the QSI decoders have a talk back feature that helps in programming and debugging.

I made a video and audio recording of what the decoder says when I tried to check its speed using function 10. (See theyoutube video below) When I reverse the throttle, the loco doesn't move and it say something like "Vee -et" even though the throttle is 50 percent of max. In the forward direction it says the correct numbers as it speeds up. I think the "vee-et" sound from the decoder is how the QSI decoder pronounces zero.

The only other O scale DCC equipped loco I have runs normally, so it's probably not the Easy DCC system. Anyone that familiar about QSI decoders know what the problem might be?

Update: I spoke with Tony's Train Exchange and they will replace the decoder under warranty. Tony Parisi, the owner and DCC expert, believes that one of the output transistors has failed. But he suggested doing a hard reset by shorting certain output leads as mentioned in the user's manual. I will try that, but I am not hopeful. If the hard reset doesn't work, they will replace the decoder with a new series of QSI decoders called the "Titan." In either case I need to disassemble the loco.

This might be a good time to do a batch installation and get the last three locos converted to DCC.

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