VT100.net: Digital VT102 User Guide

Table 9-1 Problem Checklist
Symptom	Possible Cause	Corrective Action
ON LINE or OFF LINE is on with no cursor on screen.	Screen brightness too low.	Enter SET-UP and increase screen brightness.
ON LINE and OFF LINE are not on with no keyboard response. Cursor on screen.	Keyboard cable not connected to terminal.	Connect keyboard cable.
KBD LOCKED is on.	Characters are typed faster than terminal can transmit them.	Cleared when terminal transmits characters in keyboard character buffer to computer.
	Locked condition occurs when terminal is receiving characters with half-duplex communication selected (by modem control SET-UP feature). Terminal cannot transmit characters when receiving characters in half-duplex.	Cleared when line turns around and terminal can transmit keyboard characters.
	Print operation selected while off-line.	Cleared when print operation ends.
	Terminal not connected to computer correctly. Communication line signals are not correct.	Cleared when correct connection exists between computer and terminal.
Terminal does respond to typed characters.	Computer cannot update screen.	Press NO SCROLL.
Terminal does respond to typed characters.	Computer turns keyboard off.	Computer turns keyboard on.
Garbled or error () characters or no characters appearing on screen.	Incorrect SET-UP feature selected.	Correct SET-UP features.
	Computer error occurred.	Check computer system.
Two characters appear on screen for each character typed.	Local echo on.	Turn local echo off.
Several bell tones during power up, reset or recall.	Read or write problem with user permanent memory.	Check SET-UP feature settings and try save operation.
Printer does not print characters.	Printer and terminal features do not match.	Check SET-UP feature settings of terminal and printer.