DEC VT420 - VT420 Self-Test Chart

12 Troubleshooting and Testing
• Set the terminal to VT100 Mode in the General Set-Up screen. In
VT100 mode, you can press
F11
to generate an ESC character. See
Chapter 5 for a description on using set-up.
Table 2–2 VT420 Self-Test Chart
Self-Test Prerequisites Sequence

Power-up None Turn the
terminal on.
Selected while the
VT420 is operating.
Set-up
– Local mode
Once:
ESC [ 4 ; 1 y
Continuously:
ESC [ 4 ; 1 ; 9 y
RS-232 port data lines
loopback†
RS-232 loopback connector Once:
ESC [ 4 ; 2 y
Continuously:
ESC [ 4 ; 2 ; 9 y
RS-232 port control lines
loopback†
RS-232 loopback connector Once:
ESC [ 4 ; 6 y
Continuously:
ESC [ 4 ; 6 ; 9 y
Printer port loopback DEC-423 port loopback
connector
Once:
ESC [ 4 ; 3 y
Continuously:
ESC [ 4 ; 3 ; 9 y
DEC-423 port loopback DEC-423 port loopback
connector
Once:
ESC [ 4 ; 7 y
Continuously:
ESC [ 4 ; 7 ; 9 y
Screen alignment pattern Set-up
– Local mode
ESC 8
Run all above tests, except
screen alignment pattern.
See individual tests. All
loopback connectors must be
connected.
Once:
ESC [ 4 ; 0 y
Continuously:
ESC [ 4 ; 0 ; 9 y

Do not type spaces between the characters in any escape (ESC) sequence. The sequences
are shown with spaces for clarity only.
† Worldwide models only.