EMERGENCY!!! Broken Samsung 42" Plasma HPT4254X/XAA

[Nigel Goodwin]

I did not have any bad caps in my TV, but they were CapXon which are not the best brand.

Bit of an understatement - they are absolutely terrible capacitors, and it's worth changing them as a matter of course.

It's the Capxon capacitors that kill most Samsung TV's.

 

[carmusic]

After a lot of searching on the web I have found the problem.

The problem is that a few mosfets are mounted together on a small heatsink-the 2nd from the left-and they typically run so hot over time they break down and eventually stop working.

Checked them and 3 of them read open.

Have bought replacements already but they will take about a week to get here.

I am thinking of putting a [quiet] fan in the TV to circulate the air more.

It's SO amazing that a small cheap part can cause something (worth thousands more) to break, and yet people just throw that stuff away!

there is no fan in the TV?? My panasonic 42" has 3 fans in it!! I can feel the warm air getting out of TV

 

[Nigel Goodwin]

there is no fan in the TV?? My panasonic 42" has 3 fans in it!! I can feel the warm air getting out of TV

The early plasma's had fans, later ones take less power and don't have fans - they still use more power and run hotter than LCD's though.

 

[ben7]

there is no fan in the TV?? My panasonic 42" has 3 fans in it!! I can feel the warm air getting out of TV

Yeah mine didn't have any fans in it. If the mosfets overheat again, I am going to fit some fans in it as I have a junk box full of them.

 

[koloff]

You would have to replaced all the mosfets, although they seems to be good. They will break down after a period of time and eventually short out and damaged the small diodes and resistors on the bottom of the PC board.

 

[Meteoro]

Ben, thx for the heads up. Mine just died a few mins ago with the same symptoms. Going to troubleshoot tomorrow. Where did you buy the transistors? Any specific brand you recommend? Thx in advance

 

[ben7]

Ben, thx for the heads up. Mine just died a few mins ago with the same symptoms. Going to troubleshoot tomorrow. Where did you buy the transistors? Any specific brand you recommend? Thx in advance

TBH I don't remember where I got the repair kit.

The four MOSFETs that the repair kit included were:
2x FQP9N50C ----- TO-220F
2x FQA13N50C --- TO-3PN

If any of the capacitors are bulged, I recommend replacing them too!

 

[chris taylor]

Check for dry joints fet's center heatsink. If ok disconnect supply to YSUS board and check if power supply stays running. Let me know what happens

 

[tvtech]

A new laptop (cheapy one) that my mom got will not properly install anything on it; it tells you that the installation is corrupted!-LOL it is made by ACER and it has windows7.ACER IS the WORST computer company ever

LOL

My Acer is going to be six years old this December. Best Lappie I ever purchased. It has worked every day for @ least 8 Hours....since new.

No problems ever. Just the screen is getting dim. As to be expected.

Regards,
tvtech

 

[chris taylor]

After further research you may require a kit of parts to repair your plasma TV. This is available from Chas Hyde & Son Ltd. For your PSU type you want kit P/ No. KT67 £26.34. Hope this will help

 

[thedoc8]

I have used Acer laptop and tablets for over 20 years and is the best.

 

[Menticol]

I noticed this is an old post, but looks like the topic is still going. If you still need the service manual for HPT4254X/XAA I've attached it.

PS: If you ever need a service manual, ask on a Latin-american repair forum, not on those ridiculous sites that charge a fortune. The "repair instead of throw out" philosophy still applies here, and a lot!