Dell 1707Fp Problem

[irobot]

Hi All

Regarding a Dell 1707Fp LCD monitor -

Here's the symptom: After few minutes screen turns completely white.

At the time this happens, voltages on several pins of the DC-DC converter (AAT1164, Advanced Analog Technologies) drop. The cathode of the barrier diode off Pin 21 drops from approx +11V to approx. +4.8V.

Cycling the power off then on restores operation, but again after a few minutes turns white again.

I suspect the AAT1164, but can't find it anywhere.

Any ideas would be welcome and much appreciated!

[jts1957]

Can you substitute with an external power source as "test"?

Just make sure ratings are similar. If, for example, the 11 volt supply you mention is up to 3 amps, you could use a 12 volt supply (at any current rating equal or exceeding 3 amps) as a "test."

If problem still occurs, is in monitor ... if problem solved, is in power source.

[irobot]

Thanks for the suggestion.

That was my next test. The DC converter has overcurrent and thermal protection built in. If it's not the chip itself, something else is pulling it down. It does get very toasty.

[irobot]

Hi again

After some re-evaluation, it would be difficult to try and sub outboard power supplies.

The AAT1164 is specifically designed as an LCD TFT screen power supply. It has many other pins driving the screen for various other functions. The IC itself is powered from +5V (which checks good) from off the main AC P.S.

I have tried component cooler, with no change in symptoms.

Any other ideas?

Thanks!