Acer AL708 AL708 Monitor Service Guide - Page 3

SAFETY PRECAUTIONS 1. CAUTION: No modification of any circuit should be attempted. Service work should only be performed after you are throughly familiar with all of the following safety checks and servicing guide lines. 2. SAFETY CHECK Care should be taken while servicing this LCD display. Because of the high voltage used in the inverter circuit. These voltage are exposed in such areas as the associated transfomer circuits. 4-6 Voltage measured must not exceed 1.5 volt RMS, from any exposed metallic part to the ground. A leakage current tester may be used in the above hot check, in which case any circuit measured must not exceed 1.0 miliamp. In the case of a measurement exceeding the 1.0 miliamp value, a rework is required to eliminate the chance of a shock hazard. AC VOLTMETER 3. POWER SUPPLY REQUIREMENTS The external powr converter for this display utilizes AC and DC cords , AC cord is detachable , but DC cord is permanently attached . Any attempt to replace another adapter could result in serious problem on the display. V To Metal Parts 0.15u . 1500 10W Earth Ground 4. LEAKAGE CURRENT HOT CHECK 4-1 Plug the AC cord directly into the AC outlet. Do not use an isolation transformer during this check. 4-2 Connect a 1500 ohm , 10 watt resistor , paralleled by a 0.15uF capacitor between each metallic part and a good earth ground. 4-3 Use an AC voltmeter with 1000 ohm / volt or more sensitivity and measure the AC voltage across the combination 1500 ohm resistor and 0.15uF capacitor. 4-4 Move the resistor connection to each exposed metallic part and measure the voltage. 4-5 Reverse the polarity of the AC plug in the AC outlet and repeat the above measurement. L7EA (AL708) B