Faulty Board Isolation; Self Test - Agilent Technologies 4284A Service Manual

3-10. FAULTY BOARD ISOLATION

When repairing the HP 4284A, firstly you must find the faulty board. T h i s paragraph pro-
vides the information for isolating the faulty board.

3-10-1. SELF TEST

Self tests are the 4284A's special functions used for making troubleshooting the digital con-
trol group. T h e 4284A's self tests can be categorized into three types, (1) power-on self test,
(2) self test selected with softkeys, and (3) self test selected by a bit switch.
(1) Power on self test
Every time the 4284A is turned on it performs a power-on self test as part of the power
on sequence. The 4284A performs the following self tests at power-on.
• R O M check sum test
• R A M R/W test
• E E P R O M check sum test
If the power-on self test fails, one of the error messages listed in Table 3-11 will be
displayed.
Error Message
RAM TEST ERROR
ROM CHECK SUM ERROR NO=XX
SYSTEM DATA CSUM ERROR
CORR DATA CSUM ERROR
CALIB DATA CSUM ERROR
SCANNER DATA CSUM ERROR
Table 3-11. Error Messages
Description
The RAM R/W test failed.
The check sum of one of the programmed ROMs on
the A7 board is incorrect. The ROM number with this
message is shown on A7 service sheet, SECTION 4.
The check sum of the data on the SYSTEM CONFIG
page in EEPROMs on the A7 board is incorrect.
The check sum o f the data o n t h e CORRECTION
page in EEPROMs on the A7 board is incorrect.
The check sum of the calibration data in EEPROMs
on the A7 board is incorrect.
The check sum o f the correction data for the multi
correction i n EEPROMs o n t h e scanner I / F board
(A40) is incorrect.
3-35
_ a
73 CA
0 CD
• "• o"'
0.)
•.<
0 C r ,
CD
(/)
0
CD