Dell E773c Series, Руководство по обслуживанию

Страница: 6 / 50

6
2-2 PRODUCT SAFETY NOTICE
Many electrical and mechanical parts in this chassis have special safety visual inspections and the
protection afforded by them cannot necessarily be obtained by using replacement components rated
for higher voltage, wattage, etc. Before replacing any of these components read the parts list in this
manual carefully. The use of substitute replacement parts which do not have the same safety
characteristics as specified in the parts list may create shock, fire, X-RAY radiation or other hazards.
2-3 SERVICE NOTES
1. When replacing parts or circuit boards, clamp the lead wires around terminals before soldering.
2. When replacing a high wattage resistor (more than 1/2W of metal oxide film resistor) in circuit
board, keep the resistor about 10mm (1/2 in) away from circuit board.
3. Keep wires away from high voltage or high temperature components.
4. Keep wires in their original position so as to reduce interference.
2-4 HIGH VOLTAGE WARNING
Operation of monitor outside of cabinet or with back removed may cause a serious shock hazard.
Work on this model should only be performed by those who are thoroughly familiar with precautions
necessary when working on high voltage equipment.
Exercise care when servicing this chassis with power applied. Many B plus and high voltage
terminals are exposed which, if carelessly contacted, can cause serious shock or result in damage to
the chassis. Maintain interconnecting ground lead connections between chassis and picture tube dag
when operating chassis.
Certain HV failures can increase X-ray radiation. Monitor should not be operated with HV levels
exceeding the specified rating for the chassis type. The maximum operating HV specified for the
chassis used in this monitor is
24.8KV
±
1KV
with a line voltage of 120/240 VAC. Higher voltage may also increase possibility of failure in HV
supply.
It is important to maintain specified values of all components in the horizontal and high voltage
circuits and anywhere else in the monitor that could cause a rise in high voltage or operating supply
voltages. No changes should be made to the original design of the monitor. Components shown in
the shaded areas on the schematic should be replaced with exact factory replacement parts. The
use of unauthorized substitute parts may create a shock, fire or other hazard.
To determine the presence of high voltage, use accurate, high impedance, HV meter connected
between second anode lead and CRT dag grounding device. When servicing the High Voltage
System, remove static charge from it by connecting a 10K ohm resistor in series with an insulated
wire (such as a test probe) between picture tube dag and 2nd anode lead.(AC line cord disconnected
from AC power outlet.)
The picture tube used in this monitor employs integral implosion protection. Replace with tube of the
same type number for continue safety. Do not lift picture tube by the neck. Handle the picture tube
only after discharging the high voltage completely.