Changhong Electric PF2939, Service Manual, Page: 3 / 47

SERVICE MANUAL
SAFETY INSTRUCTIONS AND MAINTENANCE
WARNING: BEFORE SERVICING THIS CHASSIS, READ THE
“
X-RAY RADIATION
PRECAUTION
”
,
“
SAFETY PRECAUTION
”
AND
“
PRODUCT SAFETY NOTICE
”
INSTRUCTIONS BELOW.
X-RAY RADIATION PRECAUTION
1. The EHT must be checked every time the TV is serviced to ensure that the CRT does not emit
X-ray radiation as result of excessive EHT voltage. The maximum EHT voltage permissible in
any operating circumstances must not exceed the rated value. When checking the EHT, use
the High Voltage Check procedure in this manual using an accurate EHT voltmeter.
2. The only source of X-RAY radiation in this TV is the CRT. The TV minimizes X-RAY radiation,
which ensures safety during normal operation. To prevent X-ray radiation, the replacement
CRT must be identical to the original fitted as specified in the parts list.
3. Some components used in this TV have safety related characteristics preventing the CRT
from emitting X-ray radiation. For continued safety, replacement component should be made
after referring the PRODUCT SAFETY NOTICE below.
4. Service and adjustment of the TV may result in changes in the nominal EHT voltage of the
CRT anode. So ensure that the maximum EHT voltage does not exceed the rated value after
service and adjustment.
SAFETY PRECAUTION
WARNING: REFER SERVICING TO QUALIFIED SERVICE PERSONNEL ONLY.
1. The TV has a nominal working EHT voltage. Extreme caution should be exercised when
working on the TV with the back removed.
1.1 Do not attempt to service this TV if you are not conversant with the precautions and
procedures for working on high voltage equipment.
1.2 When handling or working on the CRT, always discharge the anode to the TV chassis before
removing the anode cap in case of electric shock.
1.3 The CRT, if broken, will violently expel glass fragments. Use shatterproof goggles and take
extreme care while handling.
1.4 Do not hold the CRT by the neck as this is a very dangerous practice.
2. It is essential that to maintain the safety of the customer all power cord forms be replaced
exactly as supplied from factory.
3. Voltage exists between the hot and cold ground when the TV is in operation. Install a suitable
isolating transformer of beyond rated overall power when servicing or connecting any test
equipment for the sake of safety.
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