Pan. TH-42PX80B Intermittent Dark, Pinkish picture.

[Alastair E]

Re: Pan. TH-42PX80B Intermittent Dark, Pinkish picture.

Finally worked out just Where this UML drive signal comes from.

Its created in the 'Discharge-Control' chip, IC 9500, comes out on pin 4.

Between pin 7 of SS23 and this chip, there's a 470 ohm resistor, couple of plugs/ribbons, C2 board that has a Buffer chip, and then onto pin 7.

Ive attached a scope to pin 4 of IC 9500, (Actually a convenient Via, that I soldered a strand of wire to, and using some blu-tack have positioned the scope-probe firmly in place attached to this strand.

Bloody thing hasn't faulted since......

[Alastair E]

Re: Pan. TH-42PX80B Intermittent Dark, Pinkish picture.

It took all day--but finally the set faulted again. The signal output from the IC 9500 still present.

So, out with the C2 board and attach a wire to the input of the Buffer-chip.

This buffer is all thats now between SS23 pin 7 and the improvised signal test-point.

Again I play the waiting-game hoping it'll go off to see whether that buffer is at fault....

[Alastair E]

Re: Pan. TH-42PX80B Intermittent Dark, Pinkish picture.

Set faulted again, signal to input of buffer disappeared.

Between the Buffer on the C2 board and the Discharge-Control-chip IC9500, there's a 470 ohm resistor, many Vias and the ribbon connecting the A board and the C2 board.
--I should add, that one of the first things I did yesterday was to clean both ends of the ribbon and its sockets--Made no difference.....

Thinking I'm gonna hard-wire a 470 ohm to my first test-point, cut the print at some convenient point, and join this new 470 ohm to my second test-point, completely cutting out the original trace, loads of Vias and the ribbon as well as the original 470 ohm.....

That'll do it!