Phillips monitor won't turn on

[Snype32]

I have an older phillips lcd that has a strange problem. When I first plug it in after it has been sitting a while, it will not turn on. No green /orange led...nothing. I opened it up and all the caps look ok, and i found out that if I have the AC plugged in and disconnect and reconnect the power cable from the power supply to the board with the display connections, it will start right up. I can even power it off and on normally no problem. However, the problem shows up again if I leave the the LCD unplugged for a while. Any ideas?

Thanks!

[IamCanadian]

Re: Phillips monitor won't turn on

What voltage do you get for Stb power? check when working and when not turning on.

[Snype32]

Re: Phillips monitor won't turn on

Where do I check that? I don't see any label.

Thanks!

[budm]

Re: Phillips monitor won't turn on

OK, the power supply will be running the minute you have it plugged it into the AC outlet, it only has single AC output that is rectified by the Common Cathode TO-200 Diode mounted on the heat sink, the center pin (Cathode) of that Diode should have about 12~18VDC (Black probe to the chassis ground for secondary ground ref. point). That 12~18vdc gets step down by the buck converters that convert it down to 5V and also may be 3.3V for running the logic board.
I suspect the small start up cap, you can try heating that cap with hair dryer to see if the monitor will start right up every time you hit the power switch or might as well change out that cap. Second possibility will be some thing in the buck converter circuit.

[imp]

Re: Phillips monitor won't turn on

Every cap seem to be CapXon May be as simple as changing capacitors.

[FIXITNOW]

Re: Phillips monitor won't turn on

model number as one of us may have done one ??

[Snype32]

Re: Phillips monitor won't turn on

Thanks for all the replies! Sorry I have been busy and have not been online for a while. I tested the middle lead on the diode mentioned and got very close to 12v. I will try the heat on the cap and reporrt back.

Thanks for all the help so far. This site is great!

[Snype32]

Re: Phillips monitor won't turn on

As for model it's a Phillips 170b2. If it needs all new caps, I'm not sure its worth the time.

[FIXITNOW]

Re: Phillips monitor won't turn on

only seen a 170b4 on this i replaced all the caps apart from the big one