Vestel turns on ok but dim picture after 1 minute

[PowerAmpFreak]

This Vestel turns on OK, but after one minute suddenly backlight goes very dim, set continue working with sound and possible to control by remote.

According to owner, by pressing teletext button could bring back picture.

Sounds like corrupt eeprom or similair in my ears, what do you say guys?

[vinceroger69]

Re: Vestel turns on ok but dim picture after 1 minute

does the BL ON voltage drop when the backlight goes dim what board numbers are used in this set?

[dick_barton]

Re: Vestel turns on ok but dim picture after 1 minute

does the BL ON voltage drop when the backlight goes dim what board numbers are used in this set?

+1 Or the DIM voltage?

[PowerAmpFreak]

Re: Vestel turns on ok but dim picture after 1 minute

Both DIM voltage and BL ON voltage is OK when screen dims.
Forget about the corrupt eeprom thought I had initially. It must be the LED driver module then.

[dskall]

Re: Vestel turns on ok but dim picture after 1 minute

Whole screen dims? What are voltages to leds

[PowerAmpFreak]

Re: Vestel turns on ok but dim picture after 1 minute

Whole screen dims. The high side of the LED supply goes down to +24V (from +50V when screen is bright)
The two driver IC's to the right of the PCB gets really hot.

[dick_barton]

Re: Vestel turns on ok but dim picture after 1 minute

With the leds disconnected what led driving voltage do you have?

[PowerAmpFreak]

Re: Vestel turns on ok but dim picture after 1 minute

LED voltage goes to +53,5V, but soon turned off due to protection.
But I will take a look on the quick heat-up driver IC's.