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

[budm]

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

That means the main board is not sending PWM (AC) out, the same failure mode as the Philips TV.

[tom66]

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

From the service menu.

DISPLAY -> 5 -> Vol+ -> Power.

[tieny]

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

How do I check the hours?

[tom66]

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

Maybe the CCFL was sensitive to the dimming somehow, TV will no longer have dynamic backlight, but I always found that annoying anyway. Check hrs on backlight counter.

[tieny]

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

Hmm, cutting it worked. TV turns on perfectly, no dimming when it gets to the HDMI screen, its just full bright.

[budm]

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

I would try disconnect that Dim control wire and see what happen.

[tieny]

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

I don't think it can? Switching the probes around I'm getting 0VAC and same DC readings.

[budm]

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

Can your meter read frequency? The PWM for dimming is around 150~200Hz with variable pulse width, the amplitude is 0~5V typical, and since it is not sine wave the AC value reading will not make sense especially if it is not True R.M.S meter.

[tom66]

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

What meter was used for that measurement? Try measuring AC with probes reversed - sounds odd, but some meters only look at the positive cycle of any AC.

[tieny]

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

Pin 14 on the inverter connector, you can see the label by the connector. I remember troubleshooting the Inverter board for Philips Tv on the thread, we had the bl_on, the 24v, etc, but nothing on the PWMDIM, the lamps will flash on and then go out (2-second to black). Took us awhile to find out that the PWM has 0V reading (stuck low), when we disconnect the PWM pin, the backlights will stay fully on. So I am not sure if this inverter is using variable DC to control the dimming or PWM for controlling the dimmimg.

Ohh i see it, once I hit the power button itll go up to 3.24V DC then 2.32V DC when the backlights go on, and 4.5V AC

[budm]

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

Pin 14 on the inverter connector, you can see the label by the connector. I remember troubleshooting the Inverter board for Philips Tv on the thread, we had the bl_on, the 24v, etc, but nothing on the PWMDIM, the lamps will flash on and then go out (2-second to black). Took us awhile to find out that the PWM has 0V reading (stuck low), when we disconnect the PWM pin, the backlights will stay fully on. So I am not sure if this inverter is using variable DC to control the dimming or PWM for controlling the dimmimg.

[tom66]

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

Everything looks fine.. Very odd!

[tieny]

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

Is nearby bad OLP the same voltage?
What's VREF measure?

On the pad, VREF reads 5.56V, OLP measures -0.01 when lights go off and -0.09 when its on

[tieny]

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

pin 14? you mean this one? When I'm measuring it with respect to ground I'm getting a loud buzzing sound. It read around 2.5, 2.7V from what i saw I think. And getting 5.5V when set at AC

[budm]

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

Just put the meter in AC volt position. I am trying to find out if this dimming control signal is Analog dimming control type (0~5v) OO if it is PWM AC signal (around 150~200Hz) type.

[tieny]

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

how would i measure it AC

[budm]

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

What voltage do you have at the EXTERNAL DIM pin14 on the inverter board, measure it with DC and AC mode on the meter.

[tieny]

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

Heres something interesting I found...
When I'm measure this pin, (PIN #19 i think) ill be 0.01V when the backlights go on.

And as it dims when it gets to the HDMI input. It'll raise up to 1.96V steady THEN the TV actually stays on and works!! But as soon as I remove my probe from the pin the TV turns off and starts cycling through the problem again?

I had a similar problem like this with that 32" dynex, where I just resoldered the ground pins and it fixed the problem (But only lasted 20 minutes til it fully died with a main board problem and I gave up on it)

[tom66]

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

bad->"pad".
Noted there is VREF pad, so check that too.

[tieny]

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

Is nearby bad OLP the same voltage?

What do you mean by nearby bad OLP?

pin 7 (VREF) i'm measuring is 5.58V