Sony KDL40S2000

[Horty24]

Hi gurus, I'm looking for some help. My tv started to have the top half show darker than normal. I can still see the image but gets darker towards the top.
First thing that came to mind was the inverter. The power supply connects to the top inverter board then there is a ribbon that connects the upper inverter to he lower inverter. So I don't think it's the power supply? Also the top inverter stays cool but the lower one gets warm. Do I have a faulty upper inverter? How can I check or trouble shoot them? All caps look good but I can't tell about all mounted fuses. Don't know if the fuse could be a problem nor how to detect a faulty one. Thoughts or ideas?

[capkid]

Re: Sony KDL40S2000

Can you post a pic of your onscreen issue and pics of the back of the TV with the cover off?

Edit: Apparently, there's a service bulletin regarding this TV's inverter board. Check the inverter fuses to see if any are bad: Service bulletin# E33166803 <-- haven't looked very hard for a free copy of the bulletin.

[Horty24]

Re: Sony KDL40S2000

I'll Post Pics Tomorrow. Thanks For The Heads Up.

[R_J]

Re: Sony KDL40S2000

I found this: https://cdn.badcaps-static.com/pdfs/...3f0fb3a796.pdf

[budm]

Re: Sony KDL40S2000

Thanks for posting the bulletin. And here are the training manuals.

[Horty24]

Re: Sony KDL40S2000

Thanks R J & BudM. The bulletin shows my exact image, just dark on top half of screen. Except my unit does not shut down nor do i get the 4 blinks. So it must be the fuse on the inverter board. I will check today to see if its open.
It's recommends not to fix board but rather replace it. Would this be an easy fix to just replace the fuse? Seems pretty easy if that's all that needs replacing.

[tom66]

Re: Sony KDL40S2000

Sometimes fuses blow for no (apparent) reason, in which case simply replacing it is enough. But if the fuse blows again, then there is a shorted component on the inverter board. Repairable but more difficult.

[Horty24]

Re: Sony KDL40S2000

Ok I'll check fuses, replace if bad and report back

[Horty24]

Re: Sony KDL40S2000

Ok did a ohms test on the three fuses.
Fuse 1 = 0.000
Fuse 2 = 0.000
Fuse 3 = Opened.
Seems like replacement of fuse #3 on inverter board.

Going to take that puppy out and replace it.
Only thing is what type and amp is that fuse? Could not tell from schematics, I'm not good at reading those.

[tom66]

Re: Sony KDL40S2000

Usually written on the device, if not on the board next to it.

[Horty24]

Re: Sony KDL40S2000

Looks like f10? Sound right?

[budm]

Re: Sony KDL40S2000

That is PICO/PICOII Fuse made by LittelFuse (LF marking) looks like 10A.
http://www.littelfuse.com/Products/F...O%20Fuses.aspx
Blowing the 10A fuse, I would check all the MOSFETs that being fed by this fuse.

[Horty24]

Re: Sony KDL40S2000

Ok So I Changed The Fuse.. Same Result Dark Top Of Screen.
So I Checked The Fuse Again And Once Again No Good. Second Attempt RE Soldered New Fuse, Checked It After Solder And Fuse Was Ok. Connected Power To Outlet And I Hear Two Clicks The TV Has Power But I Do Not Turn TV On. Then I Unplug TV, Double Check Fuse And Once Again Blown Fuse. So Just Getting Power To TV Without Turning It On Causes Fuse T Blow. What else Can I Check?

[Horty24]

Re: Sony KDL40S2000

How Can I Check Mosfet And Where Is The Mosfet At?

[capkid]

Re: Sony KDL40S2000

The mosfets are on the back of the inverter boards. Their locations are labeled as "Q" then some number. It looks like there are 10 on each board. Post what's inscribed on the mosfets or a closeup pic of one of the mosfets. I'm guessing all 20 mosfets are the same.

[Horty24]

Re: Sony KDL40S2000

You are correct there are 10 per board. They all visually look good. How do I test them?
They are MOSFET RSS065 N06 550

[budm]

Re: Sony KDL40S2000

Look up the spec sheet and then take the RESISTANCE reading between S and D PINS.

[Horty24]

Re: Sony KDL40S2000

Ok on the top inverter board I'm getting .6 on each of the 10 MOSFET.
On the lower board I'm getting 5.3 and just continues to drop. When i go from MOSFET to MOSFET it picks up where I left off on previous MOSFET and continues to drop to lower and lower resistance.

[Horty24]

Re: Sony KDL40S2000

[budm]

Re: Sony KDL40S2000

What scale of the Ohm meter is set to? The reading is 0.6 Ohms? 0.6K Ohms< same for the 5.3 reading, Ohms, K Ohms, MOhms? The bottom line is that it does look like you do have bad MOSFETs on the top board. The hard part is that the circuits for each Inverter transformer drive circuits are in parallel so if one shorted out, it can make it looks like all of them are bad on the top board. You can leave out the blown fuses and see if all the MOSFETs on the top board will still show low resistance.