Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

[orinoco8]

Greetings! I got my hands on a Sony 40" HDTV (KDL40W3000) with no picture, but sound and backlight seem fine. I was even able to reset the whole thing to factory setting blindly with a local broadcast channel showing (with sound of course).

It's an old TV (2007 model), but fun to play with anyway instead of just throwing it away.

So it seems to be a bad T-CON board. I took it apart and found the 100 L2F capacitor(?) on the T-CON board with signs of burns. Any suggestion on where to go from here?

Kind of newbie, although I did fix another TV with no backlight several years back.

Thanks for reading and helping, everyone!

[nomoresonys]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

Check tcon see if you have voltage on each side of fuse, labeled F1 right by connector, black probe on a ground red probe on each side of fuse.

[nomoresonys]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

I'd try a tcon, starting at 13 bucks. https://www.ebay.com/sch/i.html?_fro...acat=0&_sop=15

[budm]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

"100 L2F" That is inductor for switching power supply.
What do get on the screen if you have one flat ribbon cables between T-CON and the LCD panel connected one at a time?
There are also many Voltage test points on that T-CON board.

[orinoco8]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

Thanks! I couldn't even find it without you pointing it out for me. I read about blown fuses and have been wondering about those on the unit.

Anyway, I measured and both sides read 12V. Seems to have power?

Check tcon see if you have voltage on each side of fuse, labeled F1 right by connector, black probe on a ground red probe on each side of fuse.

[orinoco8]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

Amazing! Yes, when I connect the right side ribbon only (when I face the front of TV), the right side of the screen becomes alive! Pretty good color too.

Not the other way around though: when the left ride ribbon is only connected, nothing showed.

So what do we conclude from these?

"100 L2F" That is inductor for switching power supply.
What do get on the screen if you have one flat ribbon cables between T-CON and the LCD panel connected one at a time?
There are also many Voltage test points on that T-CON board.

[budm]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

Problem in the panel, it can be as simple as shorted capacitor on the tab bonding board, you just need to check the resistance of the caps on the side of the panel that is bad.

[orinoco8]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

Thanks! I will try to get it open and take a look.

BTW, there's a yellow (slowly) blinking LED diode on the board with HDMI and PC inputs. HDMI and component inputs seem to be working (at least with sound). I am attaching a picture of that board with the blinking light at about the center and slightly top-right.

Problem in the panel, it can be as simple as shorted capacitor on the tab bonding board, you just need to check the resistance of the caps on the side of the panel that is bad.

[budm]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

You need to concentrate on the bad side of the tab bonding board at this point, do not waste time on the main board.
"when I connect the right side ribbon only (when I face the front of TV), the right side of the screen becomes alive! Pretty good color too."

[orinoco8]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

Good point!

I managed to open the front of the TV and find the narrow and long boards. Pictures of the left (suspect) board are attached. There are a few small capacitors, not what I expected. It could be a challenge to power this thing up and measure anything, since it's dismantled all over the place. Or should I just measure their resistance each?

You need to concentrate on the bad side of the tab bonding board at this point, do not waste time on the main board.
"when I connect the right side ribbon only (when I face the front of TV), the right side of the screen becomes alive! Pretty good color too."

[budwich]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

you only need to do resistance measurements across compoents.... which are most likely either shorted or open. NOTE: a number of the SMD components are paralleled so that a shorted component may cause measuring of others look like a short... :-( which means that some times you need to remove a suspect component to check the result.

[orinoco8]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

OK. Thanks!

Not too many capacitors to measure anyway. I see only a few. C1 and C2 seem to be paralleled and measured as 54K. C3 as 3.4M. But RC4 (left of C3) measures 0. What is it? I marked them in red text on the picture I took earlier on. Two sharper pictures are also attached.

There are a few on the other end, but they seem OK (even though I should double check my readings).

you only need to do resistance measurements across compoents.... which are most likely either shorted or open. NOTE: a number of the SMD components are paralleled so that a shorted component may cause measuring of others look like a short... :-( which means that some times you need to remove a suspect component to check the result.

[orinoco8]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

I did a bit of reading. According to this thread:

https://www.badcaps.net/forum/showthread.php?t=50646

it seems that I might be able to save it by cutting or removing a ribbon on the bad side (left for this unit). The question is which one to cut or remove. There are four ribbons going into the left panel from top. And four on the left side (when I face the front of the TV).

And based on this YouTube video:

https://youtu.be/T8VunfD6-Zc

someone cut about 3mm from the left most bottom (top for mine?) ribbon fixed it.

Any suggestion?

[budwich]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

well, the one youtube posted was an obvious panel damage issue so his attention was focus on that area. The other link provides you the "alternative" as he uses a piece of tape to "cutoff" the connection of pins on the tcon to panel cable / connector. You experiment to find out which ones might give a result. Because you are using tape which is a non-destructable method, it can be redone as many times as you want assuming that you are careful with connectors / ribbon cable.

further, your other post indicated a potential "unusual reading". you can potentially compare the result with similar components on either side of the edge boards to confirm differences or not.

[orinoco8]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

Good suggestion.

On the suspected RC4, the other (working) board doesn't have it installed. Just empty on the board printed with the label.

well, the one youtube posted was an obvious panel damage issue so his attention was focus on that area. The other link provides you the "alternative" as he uses a piece of tape to "cutoff" the connection of pins on the tcon to panel cable / connector. You experiment to find out which ones might give a result. Because you are using tape which is a non-destructable method, it can be redone as many times as you want assuming that you are careful with connectors / ribbon cable.

further, your other post indicated a potential "unusual reading". you can potentially compare the result with similar components on either side of the edge boards to confirm differences or not.

[budm]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

I see 9 caps, some of them labeled as BYxx.
Also check the resistance between circuit GND and test points VCOM, VDD, etc.

[orinoco8]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

I never knew BYxx were capacitors. Will do. Thanks, budm.

I see 9 caps, some of them labeled as BYxx.
Also check the resistance between circuit GND and test points VCOM, VDD, etc.

[orinoco8]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

OK. These are the measurements (all against GND):

VDD: 3.4M
VCOMG?: about 20M and slowly growing to infinity
VCOMS?: same as above
VOFF: 5.4M
most of the 8 dots on far left (CPV1, VON, VCOMG1, VST1, STV, CPV2, VCOMG2): about 10M and slowly growing to infinity.

All BYxx capacitors measure about 54K. So no shorts?

Is my digital multimeter giving me the right readings?

I see 9 caps, some of them labeled as BYxx.
Also check the resistance between circuit GND and test points VCOM, VDD, etc.

[orinoco8]

Re: Sony 40" HDTV (KDL40W3000), no picture, with sound and backlight

Tested some more:

VGMA1, VGMA2, ... VGMA9 (they are shown in the middle of the board) measured 54K against GND.

VGMA10, VGMA11, VGMA12, ... VGMA17 measured 6K.

But VGMA18 measured 2K.

OK. These are the measurements (all against GND):

VDD: 3.4M
VCOMG?: about 20M and slowly growing to infinity
VCOMS?: same as above
VOFF: 5.4M
most of the 8 dots on far left (CPV1, VON, VCOMG1, VST1, STV, CPV2, VCOMG2): about 10M and slowly growing to infinity.

All BYxx capacitors measure about 54K. So no shorts?

Is my digital multimeter giving me the right readings?