40 "Sony Bravia kdl-40S5100

[PaulSt]

Hello my fellow BadCappers!!!

I have a 40 inch sony Bravia that powers on, green ight stays lit, but there's no picture or sound. There are no obvious bad caps and i do not own an ESR meter. From what I understand this might have to do with the ysus or mainboard. any thoughts? Here are some pics for you guys. There's still a board in the top center that has yet to be uncovered. Not sure which board that is. thanks so much for helping a newbie out!!! The only thing I've ever changed before are bad caps on a power supply and this is taking it to another level for me.

[PaulSt]

Re: 40 "Sony Bravia kdl-40S5100

Alright guys, I get the message. haha. I have an extremely busy schedulte these days and I'm guilty of lookin for a quick answer w.out doin much research.I'll do more research, post some better pictures and get some voltages as soon as I can.

[tom66]

Re: 40 "Sony Bravia kdl-40S5100

Is this an LCD? Then it doesn't have a Y-sustain.

No picture or sound = Bad main board or bad power supply.

The top centre board is probably the T-con. When this goes bad you will get no picture or a distorted image but good sound.

Do you have a multimeter?

[PaulSt]

Re: 40 "Sony Bravia kdl-40S5100

Thanks, Tom.

As you can tell I don't know much about t.v. repair. or t.v.'s in general. I do have a multimeter . I have somewhat of an electronics background but i mainly when it comes to reading schematics/soldering and applying ohm's law etc. You're info is a good starting point. When I get off work today i'll do some research, read some voltages and get back to you.

[PaulSt]

Re: 40 "Sony Bravia kdl-40S5100

O.k. so I found out my old multimeter was toast. I got a new one that's on the relatively cheap side but was the winner for eevblog.com's $50 range. It's an extech 330. I also ordered the blue ESR meter and should be coming in the mail soon. So far with the nonvoltage detector I get voltage on all the boards and all parts of the board. When I take out the connector to the main board I am getting three volts on the standby pin. Here are some better pics of the boards.

[PaulSt]

Re: 40 "Sony Bravia kdl-40S5100

Also I need to note that the green light turns off when I take out the connector from the power supply to the main board. I figured this is why the only real readings I got were on the three volt standby pin. Or maybe I wasn't grounded to the right pins. Can I keep my probe on any ground pin in the socket? There are some for 12v and 15V. It requires quite a steady hand and I don't want to do any more harm than has already been caused.

[PaulSt]

Re: 40 "Sony Bravia kdl-40S5100

Well, I was testing the voltages from where the socket connects to the main board, i believe and I got all the right 12V, 15V and 3V readings. Then I heard a clicking noise and the green light doesn't even light up anymore. Guess I fried something. oh well, I tried. LOL.

[that225man]

Re: 40 "Sony Bravia kdl-40S5100

i have no pic or sound which board should i change 1st

[rmoody]

Re: 40 "Sony Bravia kdl-40S5100

Well, I was testing the voltages from where the socket connects to the main board, i believe and I got all the right 12V, 15V and 3V readings. Then I heard a clicking noise and the green light doesn't even light up anymore. Guess I fried something. oh well, I tried. LOL.

You likely blew a fuse to something, maybe on the power board. Check those first. re-check and make sure you have correct output voltages on all the pinout's, The correct voltages should be labeled on the board. As far as the black probe as a ground, you can put that to any screw on the chassis and it will read the voltage. You don't have to put it on the connector ground.

[rmoody]

Re: 40 "Sony Bravia kdl-40S5100

Is the backlight coming on at all? It's easiest to try that by turning off all the lights and try powering the tv on in the dark and see if they come on.

[PaulSt]

Re: 40 "Sony Bravia kdl-40S5100

Thanks rmoody!! No, the backlight wasn't coming on at all when the tv. was powering up. Now all the voltages coming out of the big female socket are minimal. all .01-.03. Same goes with the smaller socket that connects to the main board. However, this is with the power off. And yes I'm getting continuity on the big fuse down by the ac input

[cashkennedy]

Re: 40 "Sony Bravia kdl-40S5100

Im working on / own the exact same model right now, but have a bad panel most likely.

There are 4 major boards in this tv: the power supply, the main board, the t-con/control board (its the hidden one under the metal cage), and the inverter board.

The working correct voltages comming off my tv are very hard to read with my multimeters leads (they are too thick to fit deep into the plug), but when i finally got readings they were

stby3.3v-15v unreg grnd : 3.4v when off
the rest of the power should be off when off

then when you turn it on you should get these voltages while the load (other boards) are connected
15v unreg- 15v unreg grnd: 15.1v
12v reg - 12v reg grnd: 11.9 v
also the connector that runs to the inverter that has ~ 5-6 wires has a
12vsc - grnd wire in same connector : 11.9v

(do not take readings on the pink / white wires that are really thick as these carry enough voltage to break a multimeter)

Make sure you take readings on DC volts, and use the grnd pins that i used to test. You should get voltages readings within + or - 5% of those.

Its very easy to see when the backlight comes on cause there are a bunch of holes in the metal when the case it off that glow. (you can physically see the white plastic light spreader in many places through circular holes)

The power supply is very well built on these models (with sony and rubycon parts) and you are getting a green power light that consistently stays on so it sounds like either your main board or inverter board are the culprits but theres no way to say for sure without further testing, additionally these models often have tab bonding issues that cause a dark / blurry picture (thats what mine suffers from), and its often not fixable as its a serious defect in the way the screen was made.

You can manually start the tv / using a resistor to the stby3.3v to the power on (white wire), but im not sure what resistance is appropriate probably 1000 ohm is safe, and see if that change anything about the error.

[PaulSt]

Re: 40 "Sony Bravia kdl-40S5100

thanks so much!! One thing i do know is that there was no backlight coming on when it was powering up. I turned off lights and everything. I'll pull out a 1000 ohm resistor and try to get this bad boy to power up as soon as I can.

[cashkennedy]

Re: 40 "Sony Bravia kdl-40S5100

I didnt see that you had made your problem worse by probing around. As rmoody said you probably blew a fuse somewhere.

So check the one standby voltage while its off, and try starting the power supply using the resistor without the wires going to the mainboard and then measure the output voltages, then turn it off (remove the resistor), and connect the other wires, and try starting it with the resistor, see if the greenlight comes on and all like it used to.

You could also check the fuses on the mainboard by checking for continuity (they are often small white / beige rectangular parts soldered very close to the board like resistors. Usually marked with a F*** number identifying the part.

Also you might not need a 1000 ohm resistor, since 3.3v is often the required starting voltage, but most tv's and monitors have 5v standby... So you might just try jumping stby3.3 to power on with 1 ohm, or a paperclip / small wire if the 1000 ohm cant start the power supply.

About your original problem, was this TV working perfectly then sudenly stoped having a picture show up? Or was there a while where it got worse, or sometimes came on.

[PaulSt]

Re: 40 "Sony Bravia kdl-40S5100

Actually the t.v. stopped working after one of our close family friends had a fire at their house. The fire/water restoration company couldn't restore their t.v. as their job is to mainly deodorize/clean it. He requested his t.v's back anyway so he could tinker with them. I thought it would be fun to help out so here I am.... It was an electrical fire and the unit gave way to either a surge or from when the firefighters hosed the place down.

[cashkennedy]

Re: 40 "Sony Bravia kdl-40S5100

Eeek i was going to offer to buy the tv from you to fix mine, but now im leary lol ,
Most people on here are going to say you have little chance with water / electrical surge damage. Was the TV exposed to high temperatures, like over 130F during the fire, because all the connectors around the edge of the TV are mearly "glued" on in this model and tend to slowly warp / unstick with regular heat (100F while running) over a year. So you might have a screen that wont work from the connectors/tabs no longer being positioned correctly if the TV got rather hot.

That would not explain your backlight issues though cause thats a seperate section, (the backlight will come on fine even with the whole screen compleatly disconected (the multicolor wire running to the hidden board at the top allows you to disconect it).

On this tv the backlights are powered directly from the power supply, not using a 24v rail intermediate, if there was an electrical surge it might have destroyed parts involved in creating the backlights power on the power supply board, and not have been fuses inbetween (because normally the inverter boards have a fuse, but on this power supply i dont believe there is any large fuse between the primary and the backlights.)

And since youve additionally screwed up your power supply more while testing it (assuming it didnt just go bad at the same time randomly), your best option might be to buy a power supply for ~ 38 on ebay (payless components has one and they sell thousands of tv parts on ebay, so im sure someone on here knows if they test their components well), and see if that fixes it, if not just return the part.

Although you might still be able to fix your power supply, but it will likely take a lot of time diagnosing / testing every part. Which would start by following the instructions above about testing the standby voltage, then trying to start it manually with a resistor, and then testign the voltages afterwards. You could also test DC voltages across the big filter cap / the + and - on the bridge diode to see if your getting around 160 volts.

Furthermore, you said you visually inspected the caps, but in a power surge situation, youd more expect a FET to go bad, those are the large 3 pin blank transistors that are screwed to the aluminum heatsinks, often they go bad with no visual sign, but sometimes 1 leg will be melted, or explode off. You can also test them using a multimeter that has a diode setting which looks like this --|>-- and using the resistance function, transistors usually work where only 2 certain combinations work to pass power through them and only in 1 direction, so you take diode readings between every pin combination possible in both orders of positive and negative leads, and 2 directions / combinations should have readings, if more then 2 do, or if any combination of 2 pins have less then 200 ohms of resistance then a transistor is bad.