Dell E773c Series Service Manual

Also see for E773c Series: Setup guide

Contents

Dell E773c Series Service Manual Manual pdf 5 page image

52. PRECAUTIONS AND NOTICES2-1 SAFETY PRECAUTIONS1. Observe all caution and safety related notes located inside the display cabinet.2. Operation of the display with the cover removed, may cause a serious shock hazard from thedisplay power supply. Work on the display should not be attempted by anyone who is notthoroughly familiar with precautions necessary when working on high voltage equipment.3. Do not install, remove or handle the picture tube in any manner unless shatter-proof goggles areworn. People who are not so equipped should be kept away while handling picture tube. Keeppicture tube away from the body while handling.4. The picture tube is constructed to limit X-RAY radiation to 0.5 mR/HR. For continued protection,use the designated replacement tube only, and adjust the voltages so that the designatedmaximum rating at the anode will not be exceeded.5. Symbol“ “ means safety relative parts. The use of substitute replacement parts which do nothave the same characteristics as specified in the parts list may create shock, fire or explode etc.6. Symbol“ ” means X-ray relative parts. Before replacing any of these components pleaseread the parts list in this manual carefully to avoid creating higher anode voltage or x-ray.Especially for sealed controls, such as VR902 and FBT screen VR etc, which were sealed by themanufacturer once their optimum position has been set, please don’t dismantle them as yourlikes, otherwise you will break or damage the component. If you need replace the parts withsealed control, please adjust the relative VR to make sure the B+ voltage about 66.0V and wellseal it with A+B glue or equivalent, which you can not move away with one screw driver7. Before returning a serviced display to the customer, a thorough safety test must be performed toverify that the display is safe to operate without danger or shock. Always perform an AC leakagecurrent check on the exposed metallic parts of the cabinet, such as screw heads.Test method for current leakage is described as follow.(a) Plug the AC line cord directly into rated AC outlet (do not use a line isolation transformerduring this check).(b) Use an AC voltmeter having 5000 ohms per volt or with more sensitivity in the followingmanner: Connect a 1500 ohms 10 Watt resistor, paralleled by a 0.15UF, AC type capacitorbetween a known good earth ground (water pipe, conduit, etc.) and the exposed metallicparts simultaneously. Measure the AC voltage across the combination of 1500 ohmsresistor and 0.15UF capacitor.(c) Reverse the AC plug at the AC outlet and repeat AC voltage measurements for eachexposed metallic part.(d) Voltage measured must not exceed 0.5 volts RMS. This corresponds to 0.35 milliamp AC.Any value exceeding this limit constitutes a potential shock hazard and must be correctedimmediately.