Kogan KGNFHDLED40C PSU crapped out ...

[pedro]

Re: Kogan KGNFHDLED40C PSU crapped out ...

OK latest obs:

On application of power (NOT turn-on) both +12 and +24 appear for ~2 secs then disappear. Hitting ON causes both to power up for ~10 secs then a sub-second flash of backlight and both rails drop again.

Trusting the Leke schematic (unless stated otherwise, as it sems pretty relevant) the drive to T1 is def. affected, presumably by the PFC being disabled.

[R_J]

Re: Kogan KGNFHDLED40C PSU crapped out ...

Without the pfc circuit working, the 12 & 24 volt circuit will not be able to stay running, it will try but without the higher voltage and constant current being supplied to that circuit it will shut down due to the protection and feedback circuits. The fact it works at all means it is likely ok, So once the pfc circuit is repaired I suspect the 12 & 24 volts will be stable, and the tv will operate properly

[pedro]

Re: Kogan KGNFHDLED40C PSU crapped out ...

Have ordered 2 replacement FETs and a driver IC for the PFC circuit.

just for giggles while I wait, I powered up the board all fully connected (FET absent ...) and checked the PFC driver (L6562D) gate drive output pin vs VDC-. Nil DCV and only ~30mV AC present. Presumably either a shutdown beat me to it or the chip is compromised. Either way a spare is en-route so the chip may get the chop.

Sit and wait time.