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

[tieny]

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

I found the diodes for the left and right transformers but couldn't find the one for the middle one.

Both D101 and D103 measure at 3.63V when the backlights come on and 0V when off then itll increase by 0.04V with each cycle.

[tom66]

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

OK, looking at pic:
https://www.badcaps.net/forum/attach...9&d=1359332628

D101 is one diode for the error feed back.
There will be one other diode for each transformer.

Check the single lone pin for a voltage on each diode.

[tieny]

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

more photos

[tom66]

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

Seems OK. Looks to use a design where the middle of the panel is driven using a smaller transformer, odd design. I'd look elsewhere on the inverter, can we have close up pic around each transformer?

[tieny]

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

heres what I got (see photo)

[tom66]

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

It is Samsung LCD, so it uses U-shape CCFL
http://backlightweb.co.uk/images/lar...ture%20007.jpg

So each group of two pins (going to transformer secondary) is one bulb connection; that is where you should test.

[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?

[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)

Here it is.

[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)

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?

[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?

[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)

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)

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

[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)

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)

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)

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)

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