Philips Color Monitor 105S5, Руководство по обслуживанию

Страница: 3 / 84

Safety Precaution
PHILIPS Confidential – Do Not Copy 105S5 I-2
1. CAUTION .
No modification of any circuit should be attempted. Service work should only be performed after you are thoroughly
familiar with all of the following safety checks and servicing guide lines.
2. SAFETY CHECK.
Care should be taken while servicing this CRT display because of the high voltage used in the defection circuits. These
voltages are exposed in such areas as the associated flyback and yoke circuits.
3. FIRE & SHOCK HAZARD.
3-1 Insert an isolation transformer between the CRT display and AC power line before servicing the chassis.
3-2 In servicing pay attention to original lead dress especially in the high voltage circuit. If a short circuit is found, replace
all parts which have been overheated as a result of the short circuit.
3-3 All the protective devices must be reinstalled per original design.
3-4 Soldering must be inspected for possible cold solder joints, frayed leads, damage insulation, solder splashes or sharp
solder points. Be certain to remove all foreign material
.
4. LEAKAGE CURRENT COLD CHECK.
4-1 Unplug the AC cord and connect a jumper between the prongs on the plug.
4-2 Turn the CRT display power switch “on”
4-3 Measurement the resistance value with an ohmmeter between the jumpered AC plug and each exposed metallic part on
the CRT display such as the metal frame, screwheads, control shafts, etc. When th e exposed metallic part has a return
path to the chassis, the reading should be 1.8 MegaOhm minimum.
5. LEAKAGE CURRENT HOT CHECK.
5-1 Plug the AC cord directly into the AC outlet. Do not use and isolation transformer during this check.
5-2 Con nect a 1500ohm, 10 watt resistor, paralleled by a 0.15uF capacitor between each exposed metallic part and a good
earth ground (as shown in Fig.1)
5-3 Use and AC voltmeter with 1000ohm/volt or more sensitivity and measure the AC voltage across the combination
1500ohm resistor and 0.15uF capacitor.
5-4 Move the resistor connection to each exposed metallic part and measure the voltage.
5-5 Reverse the polarity of the AC plug in the AC outlet and repeat the above measurement.
5-6 Voltage measured must not exceed 7.5 volt RMS, from any exposed metallic part to ground A leakage current tester
may be used the above hot check, in which case any current measured must not exceed 5.0 milliamp. In the case of a
measurement exceeding the 5.0 milliamp value, a rework is required to eliminate the chance of shock hazard.
Note: High voltage is present when this CRT display is operating. Always discharge the anode of the picture tube to the
display chassis
.
http://jdwxzlw.com/?fromuser=华盛维修
家电维修资料网，免费下载各种维修资料