What is EEPROM ?

EEPROM stands for Electrical Erasable Programmable Read Only Memory and also referred to as EPROM. As the name suggest, an EEPROM can be both erased and programmed with electrical pulses. Since it can be both electrically written into and electrically erased, the EEPROM can be rapidly programmed and erased in circuit for reprogramming without removing them from the circuit board.

EEPROM is also called a non-volatile memory because when power is turned off the stored data in the EEPROM will not be erased or intact. New EEPROM have no data in it and usually have to program with a programmer before it can be use. Information stored in this type of memory can be retained for many years without a steady power supply.

What is the function of EEPROM?EEPROMs are used to store user programmable information such as: -

? VCR programming information
? CD programming information
? Digital satellite receiver control data
? User information on various consumer products

EEPROM in monitor performs two functions:

? When a monitor is switch on it will copies all data or information from the EEPROM to the microprocessor. For example, the EEPROM will let the microprocessor know the frequencies at which the monitor is going to operate.

? The EEPROM is used to store the current settings of the monitor. The settings of the monitor will not be erased even when the monitor is turned off. Anytime a change is made in the monitor settings, the microprocessor updates the setting in the EEPROM. When the monitor is turn on again, the stored settings are used to set up the monitor for operation.

What are the symptoms if the MONITOR or TV's EEPROM data is corrupted or damaged?

? No high voltage (no display).

? Horizontal or vertical frequencies run.

? Cannot save (store) current setting.

? Certain control functions like sound, brightness and contrast control does not functioning.

? On Screen Display (OSD) does not function or the OSD have a corrupted display.

? High voltage shut down (EEPROM set the horizontal frequency way too low or twice the line frequency perhaps leading to failure of the horizontal output transistor (HOT)).

What is an EEPROM programmer or copier?

EEPROM seldom fail, they just lose or have their memory (data) corrupted may be due to high voltage and static discharge from a monitor. Once reprogrammed they are as good as new. As mentioned earlier, new EEPROMs are blank and need information or data to be loaded in order for it to functions. The job of copying the data into an EEPROM is done by a programmer or a copier. Programmers comes in all shapes and sizes. You can copy these devices for repair replacement only. You cannot copy them for resale without a letter of approved from the vendor who produced them. There is quite a number of companies selling EEPROM programmer:

Typical EEPROM part no:
24C02, 24C04, 24C08 etc
24C325, 24C645AT17C65, AT17C128 etc
93C06, 93C46, 93C56, 93C66 etc
25010, 25020, 25040 etc

Jestine Yong is a electronic repairer and writer. For more information about electronic repair please visit his website at http://www.noahtec.com