philips 170s wont turn on when hot

[hbsoftware]

Hi
i have a philips 170s lcd computer monitor.

it works fine but after 20 minutes or so if you turn it off it wont turn on. sometimes it will turn on but if you pull off the power cord and reconnect it it wont power up..not even the led...then after it cools down for about 5 minutes or so it will work fine again.

i replaced all the capacitors on the power source board...all capxon units
i replaced the two photocouplers
i replaced a diode and a "doube-diode thing" that i found to be the more heat-generating parts, i sourced the parts from other equipment i knew it was working.
i replaced the large bridge rectifier.
nothing solved the problem....i also noticed even after replacing parts, a high brightness on the screen, i had to put the brightness to 35%, is that normal?
i'm out of ideas...i also replaced the only non-solid cap present on the logic board

when the lcd is on, the voltage readings seem fine to me....3.3v 1,4 13,5.... i would expect higher tahan normal voltages like 7 and 17v and the monitor preventing itself from turning on....but it all seems fine, voltages don't seem to rise even after several minutes of it being turned on.

i couldn't take pictures because my camera is also broken, tomorrow i will borrow a camera and do it...meanwhile can anyone give me a few ideas so i can start to work around this problem?

P.S. sorry for the bad English..

[selldoor]

Re: philips 170s wont turn on when hot

Did it have this same problem before you changed the parts.
Check all your soldering and also look closely at all the solder joints
on the primary side and on the transformers.
Does the problem still occur if you cool the board with a fan

You are correct we need to see pictures
We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back (in the same orientation) and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed

https://www.badcaps.net/forum/attach...7&d=1280167246

https://www.badcaps.net/forum/attach...6&d=1280167246

https://www.badcaps.net/forum/attach...4&d=1280167246

[retiredcaps]

Re: philips 170s wont turn on when hot

not even the led.

No power LED could mean

1) no standby power (usually 5V) - the main board controls the power LED and needs 5V to work

2) there is a problem on the main board

PS. Your English is fine.

[hbsoftware]

Re: philips 170s wont turn on when hot

hi
the problem was there before i changed the parts...that was the reason i did it
i will post a picture... i am not experienced in advanced electronics but i have good soldering skills, so i verified over and over again all the solders and they are 100% fine....could this be a logic board issue?
i tryed the fan....was useless, and no part gets really really hot, just a little bit.

here goes a pic of the beast....it's killing my patience...
all the parts marked with the red circle were replaced for known-working replacements.
the ac socket was reinforced with solder



the white thing on top of the caps is white ink...dont confuse it with bulging caps

[selldoor]

Re: philips 170s wont turn on when hot

Picture is not really clear enough for troubleshooting and no picture of the main(logic) board at all.

Just behind the Big cap is a small cap - due to the angle of the picture I cannot tell if it is the only small cap but it could be the "startup cap" If you have a replacement you should replace it if you tell us what values it has
we can suggest alternatives.

When you say you replaced caps with" known to be working
ones" - how did you test them?

[hbsoftware]

Re: philips 170s wont turn on when hot

All the caps were removed from perfectly-working crt tv's that nobody here uses anymore....
the small cap was also replaced...22uf
i replaced all the caps with same capacity and higher voltage ones.
i tried my best with this crap camera to take a decent pic....hope you can see all the components clearly. i had to take the pic form an angle so that the camera doesnt make a shadow in the image.