Symptom: Black on-screen display(OSD)
Cure: Replace diode BZX79-C3V9 on board location 6601.
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.