Wednesday, April 8, 2009

Troubleshooting Philips CTV 21PT3932: Black OSD problem

Symptom: Black on-screen display(OSD)
Cure: Replace diode BZX79-C3V9 on board location 6601.
Repair Details:
Set used the L9.1A chassis.
Picture and sound is good; the only thing obviously wrong was that the OSD was black.
When the +3.3V supply going to the microprocessor was measured actual voltage reading was at about +5V. This indicated that the +3.3V supply regulator circuit was defective. The +3.3V supply was restored to its specified voltage output when the BZX79-C3V9 was replaced. Normal color was also restored to the OSD.

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