An older and poorly-documented plasma screen (LG 42PC3DV) apparently went 'pop' and developed dark screen.
It had the usual bad 5V rail caps (x9) of the era (mfrd 6 months in 2006), and an overloaded -VY rail. I fixed those issues, to discover that Y_SUS waveform had no 'set-down' ramp.
The mosfet generating that ramp can and does produce a -ramp, but only at the termination of the panel drive waveform, not within it. There is no gate drive signal, at the right time, to produce this ramp.
It's complicated by the fact that models subsequent to this put zero volts across the panel outside of the drive period - up to that time the panel rested at -VY in most models.
There are, of course, no schematics. The service manual includes only a module disassembly diagram and some vague flow charts.
There are 'Troubleshooting' and 'Training' manuals for different models of the era, none of which include schematics of the power train or drivers, just the signal processing cctry. None have the same connectorization, harnessing, test point nomenclature/position.
I'm counting on a 50PC1DR or 60PC1D training manual to give display waveforms for a 'return to -VY' system. There's a 42PC5DC, that exhibits the 'return to zero' system.
None of the other power semiconductors are capable of pulling Y_SUS low - but there is no gate signal at the right time to do so. There also seems to be no factory reset procedure for these dinosaurs' firmware, that doesn't involve a special harness and PC software.
Any ideas on getting this thing to perform?
It's not for me, but seems to have sentimental value for the codger who put out kilobucks, in 2006, to own it.
Assumed config of major switches-
RL