I have a broken Philips LCD TV (55PFL7008K/12) on my desk, basically the Main PCB (so called SSB) is broken due to the known issue with the bad cooling and overheating of the Fusion P120 CPU. This one was probably long dead before I got it. I tried to reflow the CPU, it failed, but this is another story.
Now I would like to use a cheap chines LCD controller (an HDVX9-AS V4.2 in combination with an PL.MS6M30K.1 for those interested) instead of the original SSB and in basic I have it all ready for reassembling, I only need to know how to provide power from the original PSU. 12V is all the new controller needs. Of course, the original PSU has to continue driving the LED back/edge light with its proper voltage (I guess 96V). That’s anyhow where my actual problem starts...
According to what I could find about it, the former SSB sends the “power on” signal to the PSU. This is, as far as I know, done by pulling down the STB (PS-ON) signal (on Pin 10 of the PSU connector) to GND. I have tried this in different ways with the PSU put down on my work bench. Neither by using a current limiting resistor or directly shorting the Pin 10 down to ground, the PSU likes to turn on an provide the other voltages (e.g. 12V on PINs 11,12,25,26).
I guess the PSU (FSP140-4FS01) is also monitoring the LED Edge-light supply voltage. On the other hand, I expected to see at least a short time long some voltages to appear on the other PINs (i.e. PINs 11,12,25,26). The Stand-By voltage on PINs 9 (3V3s) and also on PIN 10 (STB) are always there (3.4V DC).
What am I missing here?
Is it possible to turn the PSU on w/o the other connectors populated (e.g. the LED driver circuit)?
How does the STB power on signal thing work and what am I doing wrong?
The PSU is for sure in working condition, I have cross checked this with another SSB in another TV.
Can anyone help to get me out of this mess?
Cheers, have a great Christmas and a very happy new year!
Geronimo
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