How to replace IC STK391-020 on MItsi VS-5043


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How to replace IC STK391-020 on MItsi VS-5043

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swedeguy
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Jun 23, 2008, 4:05 PM

Post #1 of 4 (74 views)
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How to replace IC STK391-020 on MItsi VS-5043	Can't Post

Hopefully one of you very smart guys/gals can help me with this one. I have a vs-5043 where the Red doesn't align with the Blue and the Green. I can Adjust the Blue, but the Red will not move at all, it just stays in one place. I have been told that the IC needs to be replaced. The part I need is STK391-020 I believe and I am ready to order 3 of those (I would assume I should replace all three)
Assuming it is the IC, and if you do not think it is please let me know. How do I replace it? I found the Giant heatsink with the 3 IC's under it but I do not see any soldering points, although I am looking at it from an angle. Do I have to take that whole bottom board out, or do I just have to remove heatsink? Do I soldier this from underneath? My question really is, what do I have to do to get this to a point of actually soldiering the IC?
Any help is GREATLY appreciated.

Thanks....

Repair man
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Jun 23, 2008, 11:09 PM

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Re: [swedeguy] How to replace IC STK391-020 on MItsi VS-5043 [In reply to]	Can't Post

Hello ... Before buying new ICs first check for cold solder joints on these ICs and yes you will have to solder these from the bottom side of the chassis. These ICs heat up & cool off every time the set is turned on & off so there is a good chance it is just solder joints that have worked their way loose.

If you have to change them it is usually a good idea to change all three because if one has gone bad the other 2 are probably not too far behind. Also if you have to change them be sure to get all the old solder off thoroughly before attempting to remove the ICs or you could damage the trace lines on the circuit board.

After desoldering them and taking out the screws that hold them to the heat sink, the ICs are often stuck to the heat sink (almost like they were glued) but this is just due to the heat they generate while the set is on; you may have to give them some friendly persuasion by hitting them with a small hammer.

If you are lucky and you can get at the ICs easy enough, you may be able to desolder the heat sinks from the board at the same time you desolder the ICs then they would be much easier to remove them from the heat sink if they are stuck too tight.

When you replace the ICs bolt them in place first before you start soldering them back in this will avoid damaging the trace lines.

Also some ICs have silicone pads between them and the heat sink, if your's has these do not damage them and make sure they go back behind the new ICs. If there are no silicone pads then the new ICs will not require them either.

The old ICs may have white heat sink grease between them and the heat sink; if this grease is still OK and not too dried out, try saving as much of it as you can and apply it to the backs of the new ICs. This heat sink grease helps transfer the heat from the ICs to the heat sink.

If you need to order these ICs you can order them online by cliking here -- Dan

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(This post was edited by Repair man on Jun 23, 2008, 11:15 PM)

swedeguy
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Jun 24, 2008, 1:15 PM

Post #3 of 4 (63 views)
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Re: [Repair man] How to replace IC STK391-020 on MItsi VS-5043 [In reply to]	Can't Post

Thanks for your quick Response Dan, as you said they have to be soldered from the bottom, does that mean that whole controller board has to come out, or can the tv be flipped on its side to get to the bottom?

swedeguy
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Jun 25, 2008, 11:46 PM

Post #4 of 4 (54 views)
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Re: [swedeguy] How to replace IC STK391-020 on MItsi VS-5043 [In reply to]	Can't Post

Ok guess you can not get to the controller board by the bottom of the TV, so it looks like the whole board has to come out. Hopefully that isnt too big of a task.

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