Denon AVR-591 Service Manual page 23

4. Run the DENON Flash ROM Writer
Run the "FlashWriter7_001_forAVR1611_1911_2311.exe" on desktop of PC.
5. Communication check
(1) Click the "Check communication" button.
(2) When connection is good, then you can see the "Communication check OK." message.
(3) If connection is not good, then you can see the "Communication error!" message.
Please confirm the following
(a) Check the connection of the AV receiver/amplifier and PC. (refer to "2.Connection to AV ..." )
(b) Check the operation mode of the AV receiver/amplifier. (refer to "3.Turn on the AV ...")
(c) Check the selection of the RS-232C port number of PC.
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