HP S7650, Service Manual

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HP S7650
7
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
23.0KV
±
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.