40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

[tieny]

Just picked up a sony KDL-40EX500, the initial owner said it would turn on and then off then it would blink 6 times in a repeated cycle. There was also a repair estimate saying it is the Static Converter (Guessing the power supply?) that is the cause.

I plug in the TV and there are 6 blinks. Turn on the TV, the sony logo pops up normally, then it goes to the HDMI input screen and it suddenly shuts off and repeats this cycle 3 times then finishes off by blinking 6 flashes .

When it goes to the HDMI input screen I notice that the backlights become much dimmer.

Doing some googling, I've read that 6 blinks states a problem with the inverter board? (confused since the repair company concluded that its the psu?)

Tore the tv down to its backlights and watched the CCFLs but they all seem to be working. It would brighten up intensely then dim to half intensity (as when it goes to hdmi input) then shuts off and repeats.

I also measured the 24V pins to the inverter and am reading 26V on each (is that a little high?). Also when the on and off cycle finally stops I notice that the 26V slowly and gradually drops down until it hits zero (doesn't it usually immediately drop to zero?).

Any ideas to whats wrong?

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Check BL-ON or ON/OFF.

Dimming may be normal. Some TVs dim the screen with no picture, to save power.

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Checking BL_ON, I get 0.054V as soon as I hit the power button, and it goes up and stays steady at 3.29V when the lights come on and as it cycles through the on and off.

ON/OFF (Is that the same as Power_ON?)

Measuring Power_On, I get 3.32V steady when I press the power button through the cycle.

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

ON/OFF == BLON.

So, BLON is steady, even when backlights go out?

Can we have a picture of parts of the chassis?

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Actually no, it stays steady at 3.28V once the lights go on and then drop back to 0.05V when it goes off, and repeats

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Mkay, is there an ERROR or ERR signal labelled on inverter?

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Yep theres a BL_ERR. It measures 3.3V on standby and once the backlights turn on it drops to 0.04V then back up to 3.3V when off, and cycles

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

So, it is signalling an error.

Can I make a suggestion: Cut BL_ERR and force it low, using a 100 ohm resistor. Then see if the cycling continues. If not, then you need to suspect the inverter board itself.

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Which one should I cut? theres one output going to the main board and one going to the inverter. I'm guessing the one leading to the inverter? I'll have to find a 100 ohm resistor from a salvaged board.

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

One from inverter to main board; the signal is a message from the inverter saying "houston, we have a problem", main board says "shit guys! let's shut this whole show down" and then restarts.

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Kind of confused, the inverter board isn't directly connected to the main board. Or I'm guessing it goes through the psu first?

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Yep, it just goes thru PSU to reduce wiring clutter.

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Just put the 100 ohm resistor in place. I'm still measuring 3.3V on the BL-ERR though and theres no change at all.

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

On which end is that?

The BL_ERR on PSU needs to go to ground thru 100 ohms. Inverter side disconnected. Is this what you have done? But you still measure 3.3V?

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Ohh okay, it was on the side going to the inverter. So the right end of the resistor should go to ground?

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Alright just grounded it, okay now it turns on normal, sony logo comes up, goes to hdmi input, then backlight shuts off. With a flashlight I can see the input and also when the menu if I bring it up.

So the cycling stopped, thus the problem is with the inverter board itself?

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Yep.
Gonna need a pic of the inverter.

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Here it is.

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

OK, I'd suspect the transformers (test secondary resistance); if it's not that, could be the bulbs in the panel.

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Those are the pins toward the output to the ccfls correct? Do I just measure the resistances in circuit? pins 1-2, 1-3, 1-4, 2-3, 2-4, etc?

I also have an inductance meter.


Heres a video of the backlights when I tore it down

http://www.youtube.com/watch?v=AVvDn...ature=youtu.be

All the lamps seem to turn on fine. Would it still be a bad transformer?