Sharp 21HF2-SS, Service Manual

Page: 4 / 73

21HF2-SS
3 – 1
21HF2-SS
Service Manual
CHAPTER 3.
ADJUSTMENT PRECAUTIONS
[1] ADJUSTMENT PRECAUTIONS
This model’s setting are adjusted in two different ways: through the I2C bus control and in the conventional analog manner. The adjust-
ments via the I2C bus control include preset-only items and variable data.
CAUTION: MAKE SURE TV SET IN “NORMAL CONDITION” BEFORE SWITCH TO SERVICE MODE FOR ADJUSTMENT.
1. Setting the service mode by the microprocessor.
i) Short JA 304 & JA 307 , then tv set will switch to the SERVICE mode position, and the microprocessor is in input mode. (Adjustment through
the I2C bus control).
ii) Press the MENU key on the remote controller to get ready to select the mode (Adjustment mode, Setting mode, Check mode and Option
mode) one by one.
iii) Press the CH DOWN / UP key on the remote controller to select the item in Adjustment mode, Setting mode or Option mode.
iv) Using the VOLUME UP/ DOWN key on the remote controller, the data can be modified. Please wait approximately 200 msec for data storage
in EEPROM before select to another mode.
v) In Check mode the data cannot be changed.
vi) Disable the short of JA 304 & JA 307, it will switch to the NORMAL mode position, and the microprocessor is out of the SERVICE mode.
2. Factory Presetting.
i) Short JA 304 & JA 307, then turn ON the main power and release the short of JA 304 & JA 307 after raster appeared on the screen. Initial val-
ues are automatically preset, only when a new EEPROM is used (Judge with the first 4 bytes ).
ii) The initial data are preset as listed in page 4-2 to 7-1.
iii) Make sure the data need modification or not (Initial data).
NOTE: Once the chassis has been assembled together and ready to be POWER ON for the FIRST TIME, make sure to short JA304 & JA307 to
switch to the service mode position first and then turn on the main power switch (See 2
-
i) above).
Precaution: If haven’t done this initialization, it may possibly generate excessive Beam current.
3. For reference please check with memory map.