Philips 55PFL3907/F7 Sound and Backlight, No Video

[kdh2012]

Re: Philips 55PFL3907/F7 Sound and Backlight, No Video

Well, I jumpered the Uart Tx & Rx signals back to the FRC board (using a 1k res) and it turned on the outputs of that board. There was still no data, but the outputs were live.

So the FRC board was sending a Uart signal to the Main, but the Main was not communicating back (at least I think so).

I have ordered a Main. We'll see how it goes.

[kdh2012]

Re: Philips 55PFL3907/F7 Sound and Backlight, No Video

Sure enough, the main board did fix it. $100.

So if your FRC board has good input signals, but no outputs, check the uart, SCL & SDA signals.

I'm thinking it is firmware, but couldn't update it without a picture. I did try precisely inputting the exact arrow and enters from the remote (copying off the good board), no luck. Just not reasonable to do that blind.

[Davi.p]

Re: Philips 55PFL3907/F7 Sound and Backlight, No Video

I don't understand more my only post, maybe a was wrong.. but there's a possible reason of why, in the tv i've fixed, tcon was supplied by a power line that goes directly PSU>FRC but on FRC stays only to be enabled after FRC initialisation by a transistor network and after it goes to screen, supply voltages for FRC circuits was supplied by flat cable from mainb., since one of you said that supply tensions on FRC are ok, are we so sure of this? i have not read about 12V exiting the mainb. to lvds cable, that 12v is normally switched on by a transistor network on the mainboard. This eventually has to be checked.

[dskall]

Re: Philips 55PFL3907/F7 Sound and Backlight, No Video

Thanks for conformation. So if main board is sending data to frc then it must be lacking the enable to frc chip to turn on. I doubt if enable is routed through transistor. Probably from main chip directly to frc main chip. I may try reflow of main board chip

[kdh2012]

Re: Philips 55PFL3907/F7 Sound and Backlight, No Video

I tried a reflow twice - no difference.

The "enable" from the main to the frc board is not a single signal, as we wish it was. It is a handshaking set of signals. I checked the uart, scl & sda signals. They definitely had continuity all the way to the main IC. But the main never outputted anything on those signals. The frc did output on the uart signal, to the main.

frustrating ....

Sorry Davi.p; I don't understand what you are asking.
edit: I did have 12v going to the tcon board. Just no lvds signals. I have seen fets go bad and not supply the 12v (or 5v) to the tcon. But that was not the problem on my tv. I wish it had been ...

[Davi.p]

Re: Philips 55PFL3907/F7 Sound and Backlight, No Video

No, i was asking the presence of the 12v from mainboard to frc through the lvds cable.

[dskall]

Re: Philips 55PFL3907/F7 Sound and Backlight, No Video

Well at least we know it is main board problem. I will concentrate efforts there.

[tumoheat]

Re: Philips 55PFL3907/F7 Sound and Backlight, No Video

kdh2012, where did you buy the main board from?

[kdh2012]

Re: Philips 55PFL3907/F7 Sound and Backlight, No Video

kdh2012, where did you buy the main board from?

I got mine off of ebay. There are cheaper ones for 40" & 46" tv's. I don't know that they will work completely. So, I ponied up the $100 and bought the right one.

The p/n that I got was: BA11P4G0401 Z_2_1 Don't know if I needed the "Z" for sure or not. Better safe than sorry.

Good luck!

[tumoheat]

Re: Philips 55PFL3907/F7 Sound and Backlight, No Video

It was on Ebay yesterday but now is sold out. Should have jumped on it. I'll keep watching.
Thanks again