Panasonic TH37PA20U - 37" SDTV PLASMA DISPLAY, Service Update Information

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the current increase. This voltage is applied to the non-inverting input of the op-
Amp at pin 1 of IC551 for over current protection (OCP).
Pin 1 of the IC also monitors the status of the transformer. The network
consisting of D555, D551, R575, and C554 rectifies and filters the AC voltage at
pin 2 of the secondary of the transformer T501. The output voltage enters pin 1
of the IC for transformer sensing. Voltage regulation is achieved via the
feedback network consisting of D565, D553, and R557.
Figure 20A
The diodes D557and D560 rectify the AC output voltage at the secondary of the
transformer T501. The network consisting of C573, C574, R597, R598 and R600
achieves filtering. This output voltage, labeled VSUS, is applied to the Scan and
Sustain boards. Voltage regulation is achieved via the feedback circuit comprised
of the resistors R602-R606 and the Error Detect IC, IC553. The resistor R605 is
used to adjust the DC output of the circuit as indicated on the label located on the
display panel.
Note: The voltage level of the Vsus output is not mentioned because it is
different for each plasma display panel. This voltage level can be found on the
panel information label located on the heat sink of the panel.
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