TV Repair Questions? Ask a TV Technician
Hello and welcome to justanswer.com my name is XXXXX XXXXX I'm here to help you with your TV problem.
Can you see the backlight through the rear slots of the TV?
Do you have a volt meter?
Is the sound ok?
A voltmeter will allow you do check for proper voltages from the power supply.
Do you see the T-CON board inside your LCD TV. There will be a ribbon cable called a LVDS cable connecting it to the main board.
Can you push the clips on either side to release it from the T-CON board and gently wiggle and see if you get flickering horizontal lines on the screen?
So if you press the menu button you don't see it on the TV and now you also don't have any sound?
Thankyou for your reply,
I believe the purple haze is the backlight shining through.
Your TV has a main board and power board.
The power board is called the G board
and the main board is called the A board.
When you get your volt meter go to the main board in the middle and look for a connector called "CN19". On this connector look for pin 8 and measure the DC voltage between this pin and the metal chassis of the TV. When you have the meter's probes in place, and with the TV off but plugged in you should read 5V. If not 5V then the G power board is bad.
Now go to pin 1 on the same connector. You should read 0V. Now press the TV power on button and it should go to 5V. If not, then the A main board is bad.
Other sanity tests:
Look for connector CN301 and measure pin 13. You should have 12V with the TV on since you see the backlight. Since I cant' see your panel then this is a sanity check. If the 12V is missing that points to the G board. If it is present and the test you did on CN19 shows no 5V on pin 1 then the A board is bad.
On CN301 you should see 3.3V on pin 7 if it missing this points to the G board. If it is there it points to the A board as the culprit.
Did you read my response directly above?
The main A board has all the connectors on it. You can see what the boards look like if you click on the "ShopJimmy" links in my answer above.
Let's work on the connector CN301. You have found almost 12V on pin 13 so it means the A board needs replacing. If you go to pin 7 on CN301 are you getting 3.3V?
Thankyou for that information.
That points to the A board (main board) as being the problem so please order & replace the A board by following my link in the earlier answer.
Please be careful with how you remove the old unit and double check the board number to make sure it is correct as sometimes a manufacturer can use different boards to do the same thing.
The board number will be written in white on the component side.
That serial number doesn't match. There will be a board number on the main board that matches one of the following two boards. That is the one that you want to order.
Here is the other board that is made for your TV
Order this one
When you receive the board compare the two to make sure they are the same before you install it.
I don't work for Shopjimmy so have no control on what product they deliver to you.
Optional Information: Make: Sony Model: KDL-46S4100 Already Tried: Replaced the Main Board.
The voltage measurements that you did confirmed that the A board was bad rather than the power board being the problem.
However it sounds like you have more than one problem.
Before your TV stopped working did you have a power surge come through or a lightening storm?
As you were changing the main board then you will have touched the T-CON ribbon cable that I mentioned at the top of our Q&A session.
Please wiggle it where it plugs into the T-CON board as I mentioned above and see if you get horizontal flashing lines in the picture.
Are you getting the sound working now?
If you check out the block diagram for a LCD you can you see should have 5V & 12V reaching the T-CON. Can you please verify that.
If you have these voltages then your T-CON is also bad and you know the drill
I don't want to go down the road that the panel is bad as normally it'll fail in one part only rather than affecting the whole sceen.
I'm also assuming that you can't see the menu when you press the menu button.
It's at the end of the T-Con cable that you wiggled earlier and will be under a metal cover.
Do you want a service manual?
If you check out the block diagram for a LCD you can you see should have 5V & 12V reaching the T-CON. Can you please verify that. This will verify that the G power board is good. Your TV has suffered a few problems unfortunately.
Here is a link to the service manual that will be valid for 7 days
A failed T-Con board will produce these symptoms and it is on sale for $40 which is a good gamble IMHO.
I would change the board but if it doesn't work then you have a failed panel which as you correctly say is very expensive and not worth it. If the worst comes to the worse there is a good market on eBay for TV parts so you can redeem some of your hard earned money back from this TV
PS Let me know what happens.
Thanks for your reply,
You're getting the main voltages and the 1.5 could be caused by the faulty T-Con or from your meter.
Get the T-Con and hopefully you'll be set.