Chassis AN15V* Model 551V, 551S 56V, 56E
1. Precautions 2. Product Specifications 3. Disassembly & Reassembly 4. Alignment & Adjustments 5. Troubleshooting 6. Exploded View & Parts List 7. Electrical Parts List 8. Block Diagram 9. Wiring Diagram 10. Schematic Diagrams
WARNINGS 1. For continued safety, do not attempt to modify the circuit board. 2. 3. Disconnect the AC power before servicing. When the chassis is operating, semiconductor heatsinks are potential shock hazards. 3. Leakage Current Hot Check (Figure 1-1): WARNING: Do not use an isolation transformer during this test. Use a leakage current tester or a metering system that complies with AmericanNational Standards Institute (ANSI C101.1, Leakage Current for Appliances), and Underwriters Laboratories (UL Publication UL1410, 59.7). With the unit completely reassembled, plug the AC line cord directly into a 120V AC outlet. With the unit’s AC switch first in the ON position and then OFF, measure the current between a known earth ground (metal water pipe, conduit, etc.) and all exposed metalparts, including: metal cabinets, screwheads and control shafts. The current measured should not exceed 0.5 milliamp. Reverse the power-plug prongs in the AC outlet and repeat the test.
(READING SHOULD NOT BE ABOVE 0.5mA)
Servicing the High Voltage and CRT :
WARNING:A high voltage adjusted to the wrong value may cause excessive X-ray emissions. 1. When servicing the highvoltage system, remove the static charge by connecting a 10 kohm resistor in series with an insulated wire (such as a test probe) between the chassis and the anode lead. When troubleshooting a monitor with excessively HV, avoid being unnecessarily close to the monitor. Do not operate the monitor for longer than is necessary to locate the cause of excessive voltage. High voltage should always be kept atthe rated value, no higher. Only when high voltage is excessive are X-rays capable of penetrating the shell of the CRT, including the lead in glass material. Operation at high voltages may also cause failure of the CRT or high voltage circuitry. When the HV regulator is operating properly, there is no possibility of an X-ray problem. Make sure the HV does not exceed its specified value and that itis regulating correctly. The CRT is especially designed to prohibit X-ray emissions. To ensure continued X-ray protection, replace the CRT only with one that is the same or equivalent type as the original. Handle the CRT only when wearing shatterproof goggles and after completely discharging the high voltage anode. Do not lift the CRT by the neck.
DEVICE UNDER TEST TEST ALL EXPOSEDMETAL SURFACES
LEAKAGE CURRENT TESTER
ALSO TEST WITH PLUG REVERSED (USING AC ADAPTER PLUG AS REQUIRED)
Figure 1-1. Leakage Current Test Circuit
1-1-3 Product Safety Notices
Some electrical and mechanical parts have special safety-related characteristics which are often not evident from visual inspection. The protection they give maynot be obtained by replacing them with components rated for higher voltage, wattage, etc. Parts that have special safety characteristics are identified by ! on schematics and parts lists. A substitute replacement that does not have the same safety characteristics as the recommended replacement part might create shock, fire and / or other hazards. Product safety is under review continuously and newinstructions are issued whenever appropriate. Components identified by on schematics and parts lists must be sealed by a soldering iron after replacement and adjustment.
Fire and Shock Hazard :
Before returning the monitor to the user, perform the following safety checks: 1. Inspect each lead dress to make certain that the leads are not pinched or that hardware is not lodged...