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

[tieny]

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

Well I just got the new inverter board and no luck... Same problem.

I said that I did notice that as soon as I plug in the TV, it immediately begins to blink 6 times before it is even turned on.

Wouldn't this mean the PSU is at fault? Since there hasn't been any signal to the inverter board yet, how would it know it is bad?

[tom66]

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

Is there a pin marked INV ERR?

[tieny]

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

Theres a BL_ERR on the PSU.

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 I'd suspect one of the bulbs in the panel as being bad...

[tieny]

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

Does 26V on the 24V rail to the inverters seem high?

[tom66]

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

Yeah, that could trip an over-voltage protection (OVP) feature on an inverter. Many inverter controller chips have OVP. Usually it's set to >26V, sometimes >27V.

[tieny]

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

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?).

I'm guessing a problem on the PSU.
That fact that it doesn't drop to zero once it turns off seems suspicious.

[tom66]

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

It may be possible to adjust it. Any adjustment pots etc.?

[tieny]

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

Nope, I don't seem to see any pots.

[tom66]

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

Please check that your meter battery is good before we go on a goose chase -- change it to be sure.

[tieny]

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

Meter seems to be working good. Just rechecked everything, but only on the 24V rail I'm measuring 25.9V.

[tieny]

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

Decided to check the CCFL lamps again, i just removed the white plastic covering the lamp connections and realize that they are actually single tubes, not the U shaped lamps.

I have alot of spares from salvaged TV's and I just replaced every single one of them. no luck though... still having the same exact problem..

So ruling out the inverter and the ccfl lamps for sure.

Only thing left is the PSU to check. (The TV service also reported that the psu is the part to replace in the quote but I didn't know why. Caps were also changed already to rubycon by them.)

So the 24V is getting an output of 26V, I checked all the components near the 24V output and they all check out good..

[tom66]

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

OK, well check the other output like 12V for audio, and see if that also measures high (maybe 13V.)

[tieny]

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

On the 12V rail I measured 12.9V. seems high also?

[tom66]

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

Yeah, so you have high outputs, common across all of them, we will need a pic of the bottom of the PSU, I suspect the TL431 or feedback resistors.

[tieny]

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

more photos of the psu

[tom66]

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

See the opto coupler bridging primary-secondary marked "12V REG"? Can you get a close pic around here...

[tieny]

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

Where exactly?

[tom66]

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

This area -- need a pic around here particularly around the secondary parts.

[tieny]

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

Here it is