sony kdl46s4100, 66 volts at bl on with tv off

[capkid]

Re: sony kdl46s4100, 66 volts at bl on with tv off

but I did see where other folks were having the same problem and a good av board fixed it.

If your main board is indeed faulty, have it fixed by ModusLink PTS. This TV has all sorts of known main board issues, so you'll just end up replacing the main board again if you buy a used replacement. ModusLink charged me $70 about 6-8 months ago to repair the board for this TV.

Edit: Sorry, I was thinking of a different TV. I bought a replacement board from TristateModule - came with a 6-month warranty. You may still want to check with ModusLink, but I don't think they repair this board. People have had success with fixes to the board performed by "koshevo" on eBay: http://www.ebay.com/itm/1-857-092-21...item4ac512d931

[nomoresonys]

Re: sony kdl46s4100, 66 volts at bl on with tv off

ok, thanks, was hoping to repair it without having to get a whole board or sending it out, but not sure where the fault lies.

[capkid]

Re: sony kdl46s4100, 66 volts at bl on with tv off

ok, thanks, was hoping to repair it without having to get a whole board or sending it out, but not sure where the fault lies.

I'm guessing a BGA is faulty on most of these boards. I don't have equipment to properly replace or reflow the chip. No more Sonys for me

[nomoresonys]

Re: sony kdl46s4100, 66 volts at bl on with tv off

lol, I hear that no more for me either.

[nomoresonys]

Re: sony kdl46s4100, 66 volts at bl on with tv off

I get 3.3 from bl-on with power on and connector unplugged, thats from the mainboard, and it goes to zero when powered off, but one tech said it should read 5 volts instead of 3.3 when powered on, do you think thats why the backlights stay off, he said it seems like an open resistor on the mainboard or something to that effect, thanks for any input.

[budm]

Re: sony kdl46s4100, 66 volts at bl on with tv off

So if all the board are connected, do you get 3.3 on the bl_on pin? if you do, that means the main board is sending the correct bl_on signal. How about ps_on signal? By the way, if you pull the cable between the power supply and the main board and the backlights come on, it means the power supply/inverter are OK, but the main board keeps the BL_ON line low when they are connected, that is how you narrow down the problem to which board is bad.
The pull-up resistor is on the power supply board instead of on the main board not like the old design, they made it that way now for easier troubleshooting which used to require using 1 k resistor between BL_ON line and 5V, same for the the PS_ON line force on using the 1k resistor.
Signal can be from 2.5~5V.

[nomoresonys]

Re: sony kdl46s4100, 66 volts at bl on with tv off

So if all the board are connected, do you get 3.3 on the bl_on pin? if you do, that means the main board is sending the correct bl_on signal. How about ps_on signal? By the way, if you pull the cable between the power supply and the main board and the backlights come on, it means the power supply/inverter are OK, but the main board keeps the BL_ON line low when they are connected, that is how you narrow down the problem to which board is bad.
The pull-up resistor is on the power supply board instead of on the main board not like the old design, they made it that way now for easier troubleshooting which used to require using 1 k resistor between BL_ON line and 5V, same for the the PS_ON line force on using the 1k resistor.
Signal can be from 2.5~5V.

the pins on that connector read strange, the bl-dim reads 3.3v, the bl-on reads 183mv, sgnd reads 20.9mv, it strange the other two ie cn301 and cn302 read correctly and in volts not mvs. those are with all connected and power on.

[nomoresonys]

Re: sony kdl46s4100, 66 volts at bl on with tv off

the pins on that connector read strange, the bl-dim reads 3.3v, the bl-on reads 183mv, sgnd reads 20.9mv, it strange the other two ie cn301 and cn302 read correctly and in volts not mvs. those are with all connected and power on.

If I understand correctly, then the fault is in the power supply and not the main.

[nomoresonys]

Re: sony kdl46s4100, 66 volts at bl on with tv off

do you think the pull up resistor on the power supply is bad?

[nomoresonys]

Re: sony kdl46s4100, 66 volts at bl on with tv off

when I unplug cn301, I get 5.36 volts at bl-on, when I plug it back in I get 183mvs, strange, those are power on readings.

[budm]

Re: sony kdl46s4100, 66 volts at bl on with tv off

NO, as I indicated, when you remove the cable between the power supply and the main board then the backlights come on, then the power supply is GOOD. The pull-up resistor is ON THE POWER SUPPLY board. The transistor on the main board is in stuck on mode, that is why the BL_ON cannot go HIGH.

[nomoresonys]

Re: sony kdl46s4100, 66 volts at bl on with tv off

NO, as I indicated, when you remove the cable between the power supply and the main board then the backlights come on, then the power supply is GOOD. The pull-up resistor is ON THE POWER SUPPLY board. The transistor on the main board is in stuck on mode, that is why the BL_ON cannot go HIGH.

ok thanks, could I replace the transistor or is there a way to get it out of stuck on mode?

[budm]

Re: sony kdl46s4100, 66 volts at bl on with tv off

You will need the service manual to find out where the transistor is and how it is being driven.

[nomoresonys]

Re: sony kdl46s4100, 66 volts at bl on with tv off

had to get manual dvm, getting 3.22 volts from bl-on pin from av board and 5.36 from bl-on pin from ps, both readings are with boards unplugged at cn303, which is the connector for bl-on, but with the connector plugged in it reads .18 volts, isn't this weird?

[nomoresonys]

Re: sony kdl46s4100, 66 volts at bl on with tv off

had to get manual dvm, getting 3.22 volts from bl-on pin from av board and 5.36 from bl-on pin from ps, both readings are with boards unplugged at cn303, which is the connector for bl-on, but with the connector plugged in it reads .18 volts, isn't this weird?

could this mean that the wire connecting them could be bad?