What is EEPROM?
EEPROM stands for Electrically Erasable Programmable Read Only Memory and is also known as E²PROM. As the name suggests, an EEPROM can be erased and programmed with electrical pulses. Since it is electrically writeable and erasable, EEPROM can be quickly programmed and erased in-circuit for reprogramming without removing it from the circuit board.
EEPROM is also called non-volatile memory because when the power is turned off, the data stored in the EEPROM will not be erased or remain intact. New EEPROMs do not contain data and usually need to be programmed with a programmer before they can be used. Information stored in this type of memory can be retained for many years without a constant power supply.
What is the function of the EEPROM? EEPROMs are used to store user-programmable information, such as:
o VCR programming information
o CD programming information
o Digital satellite receiver control data
o User information on various consumer products
The EEPROM in the monitor performs two functions:
o When a monitor is turned on, it will copy all the data or information from the EEPROM to the microprocessor. For example, the EEPROM will allow the microprocessor to know the frequencies at which the monitor will operate.
o The EEPROM is used to store the current configuration of the monitor. The monitor settings will not be cleared even if the monitor is turned off. Every time a change is made to the monitor configuration, the microprocessor updates the configuration in the EEPROM. When the monitor is turned on again, the stored settings are used to configure the monitor for operation.
What are the symptoms if the EEPROM data of the MONITOR or TV is corrupted or damaged?
o No high voltage (no display).
o Horizontal or vertical frequency tour.
o The current configuration cannot be saved (stored).
o Certain control functions such as sound, brightness and contrast control do not work.
o The on screen display (OSD) does not work or the on screen display is damaged.
o High voltage shutdown (EEPROM sets the horizontal frequency too low or twice the line frequency, which may cause a failure of the horizontal output transistor (HOT)).
What is a programmed or copied EEPROM?
EEPROMs rarely fail, they just lose or corrupt their memory (data) which can be caused by high voltage and static discharge from a monitor. Once reprogrammed they are like new. As mentioned above, new EEPROMs are blank and need information or data to be loaded in order to work. The job of copying the data to an EEPROM is done by a programmer or a copier. Programmers come in all shapes and sizes. You can copy these devices for repair replacement only. You may not copy them for resale without a letter of approval from the vendor that produced them. There are quite a few companies that sell EEPROM programmers:
Typical EEPROM Part No.:
24C02, 24C04, 24C08, etc.
24C325, 24C645AT17C65, AT17C128 etc.
93C06, 93C46, 93C56, 93C66, etc.
25010, 25020, 25040, etc.