Philips PTV800, Service Manual

Page: 76 / 567

PROGRAMMING FACTORY DEFAULT VALUES
The chassis is controlled by an on-board microcomputer and peripheral parts, altogether
known as a "tuning system". The customer picture and sound adjustments are made using
either the on-set keyboard or the remote transmitter to enter commands. There are on-screen
graphics to show the "menu" list of adjustments.
Service mode makes it possible to change the values of special memory registers in the
EEPROM (IC304). These registers control the customer adjustments, PIP setups, graphics
intensity and clock calibration. These registers also make many other service adjustments
possible that previously would have been handled by conventional controls mounted on the
P.C. Board
Service Mode Entry and Exit:
Using the remote transmitter, enter the following seven-button sequence to activate the service
mode:
0-6-2-5-9-6-Menu
Depressing the "PWR" button on the front of the PTV will exit the service mode, save the
current modification, and turn the chassis off.
Important There are 81 registers within this system. Some of data held in these registers
should not be altered and others which were factory set and unique to the unit under test. It is
highly recommended that the current values held in these registers be recorded and/or
compared to the
Table 1-0 on the following page (with the differences noted). This procedure
could save a significant amount of time should a mistake occur causing an undesirable
condition to the unit under test.
Description of Service Mode:
This service mode is used for changing service control register values from their default values
to new values - this includes all factory preset conditions.
When entering this service mode, the tuning system will attempt to retrieve the current register
values that are stored in the EEPROM (IC304). If the EEPROM has never been programmed,
default data values will be stored as shown listed in the register table. See Table 1-0 on the
next page.
Depression of the "PWR" button on the front of the PTV while in this test mode, or, setting
Register 00 to "00", shall cause the tuning system to write the adjusted values to the EEPROM
IC before chassis power is turned off.
Depressing the 'PWR' button on the front of the PTV will exit the test mode and turn off the
chassis.