Your symptoms sound alot like what I experienced before my set died. At least you got almost two years out of it. See my post titled Phillips TV 27pt543s37a ch#L01.1u AC-7638 and test the components mentioned. Once I find sources for the bad parts, I'll post my results.

try this site for parts and let me know....http://www.wehaveparts.com/
yhey seem to have alot of parts...

model# 27pt543s37a

Chas# l01. 1u ac-7638

This tv is only a year and a half old. When I turn it on the picture comes on for a few seconds then the tv makes a couple of clicking noises and the screen goes black. The power light stays green and if you change the channel you will get a picture for a few seconds. you only get sound when you have the picure. I hope you could help me.

Well I took the big leap and had it repaired at a local Phillips repair shop. The part itself was about $40 and labor of course was the most at about 120...ill get the work order and let you know what part..

There appears to be several threads regarding this same problem of needing several attempts to power up unit so that it stays on (maybe someone can use this information to come up with a final solution):

http://ths.gardenweb.com/forums/load/electronics/msg0300341010556.html?
http://ths.gardenweb.com/forums/load/electronics/msg0502124025007.html?
http://ths.gardenweb.com/forums/load/electronics/msg0604415810551.html
http://www.freelists.org/archives/techassist/11-2005/msg00433.html
http://www.freelists.org/archives/techassist/11-2005/msg00435.html
http://www.freelists.org/archives/techassist/11-2005/msg00445.html

From
http://wa6ati.com/NAP-WEB.html

BRAND NAP
MODEL: MS3252S431
CHASSIS: ch L01-1U AC7638
Keyword: Shutdown
SYMPTOM: MS3252S431 ch L01-1U AC7638. horiz squeal at turn on, horiz freq off set shuts down. after sevral attempts to power up unit will come on and usually stay on.
CURE: Checking capacitors in the horizontal drive circiuit the tech found cap 2455 a 47mf25v in hdt circuit defefective. Replacing the device the symptom was cured.- Thanks to DD Mountain View, Ca.

Philips 27' TV, Model No. 27PT543S37A, May 2003

There appears to be several threads regarding this same problem of needing sevral attempts to power up unit so that it stays on (maybe someone can use this information to come up with a final solution):
http://ths.gardenweb.com/forums/load/electronics/msg0300341010556.html?
http://ths.gardenweb.com/forums/load/electronics/msg0502124025007.html?
http://ths.gardenweb.com/forums/load/electronics/msg0604415810551.html
http://www.freelists.org/archives/techassist/11-2005/msg00433.html
http://www.freelists.org/archives/techassist/11-2005/msg00435.html
http://www.freelists.org/archives/techassist/11-2005/msg00445.html

From
http://wa6ati.com/NAP-WEB.html

BRAND NAP
MODEL: MS3252S431
CHASSIS: ch L01-1U AC7638
Keyword: Shutdown
SYMPTOM: MS3252S431 ch L01-1U AC7638. horiz squeal at turn on, horiz freq off set shuts down. after sevral attempts to power up unit will come on and usually stay on.
CURE: Checking capacitors in the horizontal drive circiuit the tech found cap 2455 a 47mf25v in hdt circuit defefective. Replacing the device the symptom was cured.- Thanks to DD Mountain View, Ca.

I am having the same problems with this model that was purchased about 3 yrs ago and is now having the exact same problems described by all on this page. Any resolutions or class action suits?

tv goes off wont stay on

A big thank you to pee_wee. We just fixes 2, yes 2, tvs with his solution. My tvs had horizontal lines and shut off after a few seconds. My husband went to Radio Shack and bought the part, 5 resistors in a package for 99 cents, and fixed both of the tvs. We still have 3 resistors left. Thank you soo much

does anyone know what 2 do here i have no clue tv comes on then off after u try like 5 times it stays on