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I went in to the player and tested the serial lines for shorts or loose connections. There were none to be found. Is it possible that the RS232 transceiver has a fault even if the other serial functions (loading firmware) work fine? We've replaced the tranceivers before, but there were more overt signs of malfunction than here.


Yeah, it's using different gates of the transceiver than those needed for software loading (as we both know, this is the tuner serial port, not the back panel serial port). Could be a bad driver chip (kinda behaving like a internal driver short, isn't it?), or noise on the CPU side of the driver chip.