Phillips 42PF7220 Plasma TV

[spike3333]

Hello,



I'm new to the Forum so excuse me if I don't appear to know what I'm doing (I don't).

I have an old Phillips 42PF7220 Plasma TV that has been pretty reliable for years. I have done some of my own repairs. I replaced a Y-Buffer board in January of 2012.

Today it started acting up again. My wife turned it on and the picture appears very faint, as if it's being viewed through a black fog and the image has a red tint to it. You can see the picture in the image I posted above.

Has anyone seen anything similar on their plasma? Do any of the experts on the Forum have any suggestions as to repair. I think it's a 2004 so it may be ready for pasture. I thought I would give it a shot instead of adding to the landfill.

Thanks,

Dwight

[tom66]

Re: Phillips 42PF7220 Plasma TV

Clear cut Z-sustain / X-main failure right there.

[spike3333]

Re: Phillips 42PF7220 Plasma TV

Wow talk about prompt replies. I had just gone out to the garage to set the TV up on the bench and came back to see your reply, thank you.



In the manual I have it shows a PCB to the right of the power supply called the PDP X-Main. Is that what I want to replace? Is the Z-Sustain a separate PCB? If so could you point me in the region I should be looking for it.

Thanks again Tom,

Dwight

[tom66]

Re: Phillips 42PF7220 Plasma TV

The Z-sustain and X-main are different names for the same part, in your case, it is X-main because the panel (display) components are made by Samsung.

[spike3333]

Re: Phillips 42PF7220 Plasma TV

Tom,

I have the backcover off and it looks a little different than the manual. Is this the one:





Once I have the board out is there a chance i just need to replace some blown caps or it do I need to replace the whole board?

Thanks,

Dwight

[tom66]

Re: Phillips 42PF7220 Plasma TV

Yes, that is the X-main.

[spike3333]

Re: Phillips 42PF7220 Plasma TV

They go for $20 to $40 on eBay, I guess I'll go new.

http://www.ebay.com/itm/Samsung-HP-R...item5890a1cfaa

The ads are for "Samsung HP-R4272 X SUS Board LJ41-02758A or LJ92-01199A". Are these fairly universal or do I need to get something more specific to my model.

[tom66]

Re: Phillips 42PF7220 Plasma TV

Yes, they are universal parts. Just match the LJ41 and LJ92 numbers printed on the old X-main board to that auction, usually it is OK if the last letter (A,B,C typically) does not match but the rest must match.

[spike3333]

Re: Phillips 42PF7220 Plasma TV

Darn. One screw in the middle edge of the heat sink I can't readily get to. I guess it was all going too smoothly.

[tom66]

Re: Phillips 42PF7220 Plasma TV

You don't need to undo the heatsink. Be careful with the orange ribbons going into the glass panel; they cannot be replaced or repaired if torn.

[spike3333]

Re: Phillips 42PF7220 Plasma TV

There is a perimeter PCB screw that is accessible through a hole in the edge of the heat sink. It's under one of the vertical frame members. I have all the flex undone. I'm familiar with the ZIFF style connectors from my days with Motorola.

The TV has been unplugged and sitting in my garage for over 24 hours. Should all the caps be dissipated?

I ordered the PCB and paid for overnight shipping. Hoping I get this up and running before the Superbowl on Sunday.

[tom66]

Re: Phillips 42PF7220 Plasma TV

On the X- and Y-main boards, discharge occurs within about 10 minutes typically. The "test-before-touching" rule is a good idea, though.

[spike3333]

Re: Phillips 42PF7220 Plasma TV

Thanks again for all your help. I'll let you know how it all works out.

[spike3333]

Re: Phillips 42PF7220 Plasma TV

Hi Tom,

I got the replacement X-Main PCB and installed it. The Tv looks the same. Any thoughts?

Thanks,

Dwight

[tom66]

Re: Phillips 42PF7220 Plasma TV

We had one here which was not resolved by X-main. It turned out to be a bad component on the control board feeding into X-main. It required in depth analysis and about 100 posts but we did sort it out. I'll see if I can dig out the thread. IIRC, an oscilloscope was necessary.

[spike3333]

Re: Phillips 42PF7220 Plasma TV

Tom,

I'm second guessing whether I fully seated the small latch ZIF connector leading into the board. I'll open it back up and double check. Could this explain it?

I don't have an oscilloscope and it sounds like it will be beyond my capabilities but I would like to hear what was discussed in the earlier thread.

Dwight

[spike3333]

Re: Phillips 42PF7220 Plasma TV

Hi Tom,

Any luck locating the other thread. I was going to open the TV back up this weekend and work on it.

Thanks,

Dwight

[tom66]

Re: Phillips 42PF7220 Plasma TV

https://www.badcaps.net/forum/showthread.php?t=24872

Sorry did not see your previous posting.

[spike3333]

Re: Phillips 42PF7220 Plasma TV

OK great. I read through the thread. I don't have a oscilloscope. If I find that I have the new X-Main well connected would it be worthwhile to test the resistances across the resistor banks you indicated in the thread? I have a multimeter. I'm a mechanical engineer but am pretty clueless with electronics.

[spike3333]

Re: Phillips 42PF7220 Plasma TV



Tom,

I have the TV apart again and it appears all the connections to the X-Main are solid. Are there any tests I can do without the oscilloscope I can do? I have a multimeter. I included a picture of the logic board in my TV that is connected to X-Main by the narrow flex.

Dwight