Panasonic EURO-4H TX-32PK25D H-OUT missing

[Guest]

Panasonic TX-32PK25D
Chassis: EURO-4H

HOT (Q551, 2SC5144LB228) was defect [before this, the TV had already another defect: OSD and Teletext were hardly readable (dark, no colors, no contrast)].

Did not find any defect parts around the HOT. Replaced HOT with a 60W-lamp for test purposes. Test ok. Horizontal drive signal H-OUT was there for some minutes (but a bit dirty abraded square-pulse), then H-OUT dissapeared totally.

Tracing back brought out: HOUT is not delivered by the Digi-Modul (F Board, TNP8EF008, Pin16), respectively there from the deflection processor (IC1504, DDP3310BPSF5, Pin 8). Resoldering the Digi-Board and replacement of the 5 MHz quartz crystal X1502 (tip from panasonic service) -> no success.

Measurement at I2C bus (SDA: Pin22, SCL: Pin21, Reset: Pin23) brought out: 5 times in series data packets are sent, 5 times in series there is a reset. Then the TV switches to std.by. Same happens, when I dismount the Digi-board completely.

Does the traffic on the I2C-bus (5 tries, 5 resets) indicate, that the digi-board has (not only communication-)problems ? Does the OSD/teletext-problem harden this suspicion ? How would you proceed ? Thanks for every tip !

[Guest]

Defect disappeared after replacing the digi-modul (F Board, TNP8EF008) by a used one (new modules are not in stock since 2006). OSD/Videotext is functioning, too.

HOUT (measured at Gate of the line-preamplifier 2SK2962TPE6) was abraded a little bit and had a little knoll in the rising edge and two little overshooting oscillations on the upper plateau of the square-pulse. The oscillogram in the service-manual however shows a nearly perfect square-pulse. Checking every part from the digi-module to the line amplifier and replacing the 2SK2962TPE6 without success. Hence, this seems to be normal.

TV is functioning now for 1 week without problems.