Vt420 Self-Tests - Digital Equipment VT420 Service Manual

1 O Troubleshooting and Testing
Table 2-1 (Cont.) Troubleshooting the VT420
Symptom
Other Problems
After power-
up, one or more
keyboard LEDs
stay on. Or,
the LEDs do
not go through
their power-up
sequence.
The set-up cursor
does not appear.
When using a
modem, the
modem speed
select signals do
not work.
Worldwide
model: In PC
TERM
mode, a
modem does not
work with the
terminal.
Probable Cause
Keyboard.
'Turminal board.
'Turminal board.
Cables.
'Turminal board.
The modem's
XON
/XOFF
settings
are incompatible
with the terminal.
• Section numbers follow the solution.
2.2
VT420 Self-Tests
Solution•
Replace the keyboard (3.4).
Replace the terminal board (3.3).
Replace the terminal board (3.3).
Check all cables and cable
connections. Replace the terminal
board (3.3).
Use a modem with compatible
XON
/XOFF
settings. In PC
TERM
mode,
the terminal's
XON
point is
65
1
s
characters, and the
XOFF
point is
6716 characters.
The VT420 has a series of self-tests to determine if the terminal
board
is the faulty field replaceable unit (FRU). You can run each test from the
keyboard by entering the escape sequence for the test. Table 2-2 lists the
tests and their escape sequences.
If a test indicates the terminal board is faulty, refer to
• Chapter 4, to adjust the components on the board, or
• Chapter 3, to replace the board
After making adjustments or replacing the terminal board, repeat the
tests in this chapter to ensure the terminal operates correctly.