Power-Up Self-Test - DEC VT420 Service Manual

2.2.3 Power-Up Self-Test

This test runs automatically each time you turn on the terminal. The
test checks the terminal's internal memory, keyboard, and video circuitry.
The test also checks the communication and printer ports to see if they
are operating correctly. The individual loopback tests perform a more
complete test of each port.
You can also run the power-up self-test manually while the terminal is
operating, as follows:
NOTE
After you run the power-up self-test, all the set-up features are
automatically set to their saved values.
1. Set up the terminal (Sections 2.2.1 and 2.2.2).
2. Type one of the following DECTST sequences:
ESC [ 4 ; 1 y
ESC [ 4 ; 1 ; 9 y
While the test is running:
A message appears in the upper-left corner of the screen. The
Wait
message may disappear at times, but it reappears until the test detects
an error or the terminal's power is turned off.
NOTE
The DECTST control function causes a disconnect. Do not use
DECTST when the connection is made through a modem.
If the test is successful:
1. The keyboard's LED indicators turn off.
2. The keyboard makes a bell tone.
3. A message appears on the screen. This message disappears
VT420 OK
when any of the following events occur:
• The terminal receives any character except XON, XOFF, or NUL.
• You press any key.
• You leave the terminal on and inactive for 30 minutes.
Runs the test once.
Runs the test continuously.
Troubleshooting and Testing 13
Wait