Troubleshooting Secondary Circuits; Rectifier Section Troubleshooting; Troubleshooting Horizontal Centering - Sony CPD-420GS Training Manual

Troubleshooting Secondary Circuits

Failures in these sections are interrelated and one circuit can affect
another. Consequently, some failures will also affect the primary cir-
cuit.

Rectifier Section Troubleshooting

Rectifier diode failures are not common, but do occur. Deflection (D
Board), Video (A Board) and N Board failures contribute to diode dam-
age. In the event, a voltage is not present, check for shorts to ground or
open or shorted diodes. Also, check for any open fusible resistor and
shorted zener diodes found on the supply lines.
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Troubleshooting Horizontal Centering

A loss of the Horizontal Centering adjustment can be caused by the fail-
ures of rectifier diodes, fusible resistors, IC502 and related components.
Measure the +/- voltages in reference to the horizontal centering ground
(HN). Typically, the voltages are ±8V DC. However, the adjustment set-
ting can reduce the voltages by approximately 1V. If there are no prob-
lems found at the Horizontal Centering supply, troubleshoot the Horizon-
tal Centering circuitry.