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Old 07-31-2010, 02:29 PM   #1
bigdave85
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Default KDL40s4100, no picture or sound

Hello to all, this is my first post on the forum, thanks to all for the vast wealth of knowledge.
My problem is that I have a Sony Bravia KDL40s4100 TV. I purchased it broken, hopeing that it would be any easy fix, however none of my searches have provided me with an exact symptom.
When the power button is pushed, the power lamp shows a constant green. I hear a relay click on in the back and that is it. If I shine a flashlight onto the screen I can see that the black screen actually changes to a very faint green every ten seconds or so. I attempted to plug a DVD player into the side av ports to see if I could get any sound, however this did not work. Any suggestions as to where I should begin my diagnosis would be appreciated. Thanks Again
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Old 07-31-2010, 03:15 PM   #2
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Default Re: KDL40s4100, no picture or sound

Quote:
Originally Posted by bigdave85 View Post
Hello to all, this is my first post on the forum, thanks to all for the vast wealth of knowledge.
My problem is that I have a Sony Bravia KDL40s4100 TV. I purchased it broken, hopeing that it would be any easy fix, however none of my searches have provided me with an exact symptom.
When the power button is pushed, the power lamp shows a constant green. I hear a relay click on in the back and that is it. If I shine a flashlight onto the screen I can see that the black screen actually changes to a very faint green every ten seconds or so. I attempted to plug a DVD player into the side av ports to see if I could get any sound, however this did not work. Any suggestions as to where I should begin my diagnosis would be appreciated. Thanks Again
I assume that after plugging in the DVD player you attempted to step through the various inputs. The next step would be to remove the back and examine the power supply. Look for obvious problems like bad caps, burnt components, etc. Also check cable seating, etc.

If the power supply has output voltages marked, the next step would be to measure them and see if all voltages are present.

Beyond that, pictures would help.

PlainBill
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Old 07-31-2010, 04:39 PM   #3
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Default Re: KDL40s4100, no picture or sound

Thank you for your reply. I have attempted to switch through inputs with no success. I have removed the rear panel and have inspected for any signs or burning or unseated terminals, none found. I wil be glad to post pictures,'what of? Will be retrieving my meter from my folks house tomorrow.
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Old 08-01-2010, 06:42 PM   #4
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Default Re: KDL40s4100, no picture or sound

Bump, anyone have a similar problem before
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Old 08-02-2010, 11:58 AM   #5
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Default Re: KDL40s4100, no picture or sound

How about attaching a couple of pictures? One an overall view of the back of the TV, the second a picture of the power supply.

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Old 08-02-2010, 05:46 PM   #6
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Default Re: KDL40s4100, no picture or sound

Still working on getting those pictures posted, however I was able to check the voltages that were marked on the edge of the board at the connectors. All appear to be very close to the indicated value ( within a few Tenths)
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Old 08-02-2010, 06:12 PM   #7
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Default Re: KDL40s4100, no picture or sound

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Originally Posted by bigdave85 View Post
Still working on getting those pictures posted, however I was able to check the voltages that were marked on the edge of the board at the connectors. All appear to be very close to the indicated value ( within a few Tenths)
That's both good and bad news. The good news is it means the power supply is probably good. A replacement power supply is about $60. The bad news the other likely cause is the main circuit board, which costs more than $100 more.

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Old 08-02-2010, 06:41 PM   #8
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Default Re: KDL40s4100, no picture or sound

PlainBill, thanks for helping me with this. I'm not against spending the money, however I'd certainly rather replace one board verses two or three. I do however want to state that I checked the pins on the wires at the connections on the edge of the power supply board only. It appeared one connector went to the video board (contained the RCA and hdmi connections) and one went to the long board ( LCD inverter board?) Some of the markings showed 12v some 3.5 etc. What are some more steps or procedures I can follow until I can get the pictures posted. I've read about as many threads as I can and still cannot find someone with an exact symptoms as I have. Lots of folks are having issues with no picture yet sound remains. I have plugged iny DVD player , started it and pressed the input button on top of the TV many times hopeing to hear or see something, but no luck. I thought that I had read somewhere that I could unplug the inverter board and that may allow the audio to start working, attempted this with no luck. Does the black screen that changes to green and back mean the LCD panel itself is good?
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Old 08-02-2010, 09:38 PM   #9
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Default Re: KDL40s4100, no picture or sound

Quote:
Originally Posted by bigdave85 View Post
PlainBill, thanks for helping me with this. I'm not against spending the money, however I'd certainly rather replace one board verses two or three. I do however want to state that I checked the pins on the wires at the connections on the edge of the power supply board only. It appeared one connector went to the video board (contained the RCA and hdmi connections) and one went to the long board ( LCD inverter board?) Some of the markings showed 12v some 3.5 etc. What are some more steps or procedures I can follow until I can get the pictures posted. I've read about as many threads as I can and still cannot find someone with an exact symptoms as I have. Lots of folks are having issues with no picture yet sound remains. I have plugged iny DVD player , started it and pressed the input button on top of the TV many times hopeing to hear or see something, but no luck. I thought that I had read somewhere that I could unplug the inverter board and that may allow the audio to start working, attempted this with no luck. Does the black screen that changes to green and back mean the LCD panel itself is good?
We're already beyond my comfort level with this set. Here's a nutshell description of what happens with a TV like this. Terminology is from Philips, other manufacturers use different terms, the concepts are the same.

TV gets plugged in. Standby power supply comes up (typically 5 volts, could be higher), standby processor starts, performs a few rudimentary tests and waits until someone presses a button the control panel or on the remote. Pretty much every button is ignored except the Power button. Power button is pressed, the standby processor turns on the main supply, performs some more tests, then turns on the main processor.

Main processor turns on, performs even more tests, waking up various subsystems; eventually turns on the inverter, then starts processing the signal from the selected input. The processed video goes to the T-con board and is displayed on the screen. The processed audio goes to the audio amp and is heard on the speakers.

Possible failures:

Standby power supply - no response from the remote of control panel.

Main power supply - the power led turns off, an error code may be flashed.

Inverter - sound, but no picture.

T-con - sound, backlights on, garbage on the screen.

Audio amp - no sound, has picture.

Main board - Either picture, or sound (or both) may be missing. No recognizable display. Inverter may not be instructed to turn on.

Obviously the symptoms point to problem with the main board. There are a number of things to look for. The first is bulging caps, although Sony uses good brands IIRC. There are a number of voltage regulators on this board. One may have failed. Any BGA parts may have failed due to bad soldering. Look for any parts that have vented their magic smoke.

Every LCD and plasma TV I have encountered has some provision for hooking up a computer (usually through an adapter - $$$) that allows some diagnostics or set-up. Without the adapter and the proper software, there is little that can be done from that approach.

Some flash error codes, that can be a big help.

Absent either of those, about all you can do is look for obvious physical defects and check any voltage regulators on the board. At this point the industry is pretty much based on swapping out any cards that fail (preferably at the customer's expense).

EDIT: The service manual is available at Electrotanya. http://elektrotanya.com/sony_kdl-40s.../download.html

PlainBill

Last edited by PlainBill; 08-02-2010 at 09:47 PM..
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Old 08-03-2010, 06:35 PM   #10
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Default Re: KDL40s4100, no picture or sound

Quite possible that this not only is useless, maybe harmful, but with the tv powered on I get several flashes of light from inside the tv when I unplug and replug one of the three connectors from the video board. The lights appear to be from several locations almost bulbs, could these brief flashes be from the backlights?
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Old 08-03-2010, 07:48 PM   #11
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Default Re: KDL40s4100, no picture or sound

Quote:
Originally Posted by bigdave85 View Post
Quite possible that this not only is useless, maybe harmful, but with the tv powered on I get several flashes of light from inside the tv when I unplug and replug one of the three connectors from the video board. The lights appear to be from several locations almost bulbs, could these brief flashes be from the backlights?
Could be. You are right, the experiment is possibly harmful; certainly it's not anything constructive.

By the way, the service manual I referenced above has schematics of both the main board and the power supply.

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Old 08-03-2010, 08:52 PM   #12
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Default Re: KDL40s4100, no picture or sound

Ok, printed out the schematics, now come the hard part, I guess I will start with the main board.
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Old 08-04-2010, 09:15 PM   #13
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Default Re: KDL40s4100, no picture or sound

So I found an extra part soldered onto my video board this evening definitely looks like th e guy I bought this from tried to fix it himself, looks like he soldered a surface mount resister bridging a chip to another resister, or capacitor
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Old 08-06-2010, 02:59 PM   #14
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Default Re: KDL40s4100, no picture or sound

Just to keep anyone who is paying attention informed... I contacted the guy who I purchased the tv from, to ask if he, or anyone else had opened the tv up to attempt to repair. Not to my surprise he informed me that a technician had diagnosed his tv and attempted something ( not known) only to later state he believed it was the main board. So the mystery of the additional surface mount resister has been solved. I am still not sure that this diagnosis of the video board is correct, but that seems to be where everything is pointing. I was able to find a used board on eBay from a seller with great feedback and picked it up for cheap, I will post back my results after the part arrives.
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Old 08-15-2010, 02:17 PM   #15
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Default Re: KDL40s4100, no picture or sound

Just to let everyone know, I my mainboard in the mail a couple of days ago. I didn't have anytime to replace it until last night. 20 minutes and one used video board later I had one great looking tv. With picture and sound!! Thanks for everyones help (plainbill), I hope to continue using this site in the future.
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Old 08-18-2010, 04:32 PM   #16
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Default Re: KDL40s4100, no picture or sound

Quote:
Originally Posted by PlainBill View Post
We're already beyond my comfort level with this set. Here's a nutshell description of what happens with a TV like this. Terminology is from Philips, other manufacturers use different terms, the concepts are the same.

TV gets plugged in. Standby power supply comes up (typically 5 volts, could be higher), standby processor starts, performs a few rudimentary tests and waits until someone presses a button the control panel or on the remote. Pretty much every button is ignored except the Power button. Power button is pressed, the standby processor turns on the main supply, performs some more tests, then turns on the main processor.

Main processor turns on, performs even more tests, waking up various subsystems; eventually turns on the inverter, then starts processing the signal from the selected input. The processed video goes to the T-con board and is displayed on the screen. The processed audio goes to the audio amp and is heard on the speakers.

Possible failures:

Standby power supply - no response from the remote of control panel.

Main power supply - the power led turns off, an error code may be flashed.

Inverter - sound, but no picture.

T-con - sound, backlights on, garbage on the screen.

Audio amp - no sound, has picture.

Main board - Either picture, or sound (or both) may be missing. No recognizable display. Inverter may not be instructed to turn on.

Obviously the symptoms point to problem with the main board. There are a number of things to look for. The first is bulging caps, although Sony uses good brands IIRC. There are a number of voltage regulators on this board. One may have failed. Any BGA parts may have failed due to bad soldering. Look for any parts that have vented their magic smoke.

Every LCD and plasma TV I have encountered has some provision for hooking up a computer (usually through an adapter - $$$) that allows some diagnostics or set-up. Without the adapter and the proper software, there is little that can be done from that approach.

Some flash error codes, that can be a big help.

Absent either of those, about all you can do is look for obvious physical defects and check any voltage regulators on the board. At this point the industry is pretty much based on swapping out any cards that fail (preferably at the customer's expense).

EDIT: The service manual is available at Electrotanya. http://elektrotanya.com/sony_kdl-40s.../download.html

PlainBill
Hey sorry to interrupt post, but having the same type of problem... When i turn my tv on it is black but has some light showing like it is on but has no signal. I do have sound, but no on screen menus work nor does the picture come on.. i was reading and saw that it may b one or 2 things. the inverter or the power supply. Is there a way to tell if it the inverter? or the power supply? Sorry if it sounds dumb but i have no knowledge of lcds? ant help would b awesome.
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Old 01-11-2012, 07:40 PM   #17
G Nicholls
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Default Re: KDL40s4100, no picture or sound

ELECTROTANYA...Scam download site! No schematics, only crapp "buy me" stuff!

badcaps is a great site. Do not let this re-direct sour you on the site. Great info here.

Thanx to the moderators.

Last edited by G Nicholls; 01-11-2012 at 07:44 PM..
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Old 01-11-2012, 08:01 PM   #18
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Default Re: KDL40s4100, no picture or sound

ElektroTanya

Are you sure you know how to navigate the website? I've downloaded quite a few service manuals without any problems. I've never heard of any problems from that site. Maybe you should try again.
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Old 01-17-2012, 11:11 PM   #19
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Default Re: KDL40s4100, no picture or sound

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Originally Posted by bigdozer View Post
ElektroTanya

Are you sure you know how to navigate the website? I've downloaded quite a few service manuals without any problems. I've never heard of any problems from that site. Maybe you should try again.
Opsie!! I feel a bit dumb. I went back looking for this schematic again. At the bottom left corner of the page is a small reference to download the manual. The site works. Excuse my prior post. Thanx bigdozer. I humbley stand corrected. (But there sure are a bunch of "diversions" on the site to hoodwink a novice.)

Giddiee-up!!
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