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Board Level Troubleshooting using the Wiring Interconnect
Figure 46
Before the set can be repaired to a component level, it is necessary to determine which board is
defective. The Wiring interconnect diagram is a useful tool for this.
Dead Set
The Standby Power supply and Rectifiers are located on the Input panel. Control for power On/Off is
performed by the Microprocessor located on the SSB. This Processor is powered by the 5-volt
standby voltage from the Input Panel. For a Dead Set condition, check the 5-volt standby supply on
Pin 1 of 1102. If this voltage is present, check the Standby line on Pin 3. This line will be
approximately 2.6 volts in standby and zero volts when the set is turned On. If the Standby line goes
Low, check the 130-volt source on Pin 8 of connector 1518. If this voltage is present, the Full Power
supply on located on the Large Signal panel is working. If the Picture is not present but audio is, the
High voltage or video drive circuits may have failed. Checking the Screen voltage from the Focus G2
block will indicate whether the High Voltage circuit is working or not. Horizontal and Vertical drive from
the HOP panel must be present for the High Voltage to be present. Horizontal drive should be present
on Pin 9 of 1510 and Vertical drive should be present on Pin 3.
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