Compaq CRT Monitor s7500 Service Guide - Page 25

5-7 R.G.B. Video Amplifier Abnormal RGB Video AMP Abnormal HP S7500/MV7500/CV7500 Check waveform at I501 pin 5, 6 and 7 No Check or replace the signal cable or I501 Yes Check I502 pin 1, 2 and 3 collector voltage (normally about No 70V) & waveform Check I901 Yes Video signal present at the pin of the CRT R.G.B. Cathode Yes Defective cut-off circuit (DC restore) I503 5-8 Blank EEPROM Trouble-shooting: Description of functions for models under E1770 series EEPROM DATA AUTO-RELOAD The function allows plant staff to pre-write and customer service personnel to use blank EEPROM through the pre-write EEPROM function whenever the CPU is implemented. The method of operation isas follows: First, start after HP S7500/MV7500/CV7500 turns to () KEY. At this point of time, the CPU is capable of detecting the first 8 DATA of each page that EEPROM contains. When the reading goes to 00H or FFH, the EEPROM PAGE will turn to blank; instead, the pre-set value is being written into the EEPROM through CPU. Otherwise, it shall be deemed an effective value and that the pre-write function shall not be activated. Note: The pre-write operation is only used in the service operation, if the EEPROM becomes faulty, we need to replace it with a new one, but, to enable the adjustment ( geometry, color temperature, .. etc ) we have to put in some " factory preset values " so that we can have a good start point, this is what we call " pre-write " operation. Page 23