Asus vg248qe purple light problem

[usamy]

Re: Asus vg248qe purple light problem

hi gentlemen, I can't open a new post because I'm new. I have my asus vw246h that to make it turn on I always have to unplug. I changed all the electrolytics on the power supply board but nothing.

[Rennokas]

Re: Asus vg248qe purple light problem

Not easy to get the MP2125 ( https://www.monolithicpower.com/en/mp2125.html )
Any alternative which would fit?

[Rennokas]

Re: Asus vg248qe purple light problem

Took off L407 and resistance relative to ground from upper choke 0.3 ohm and bottom choke has 220 ohm

[lotas]

Re: Asus vg248qe purple light problem

On the L407 - 1 Om, this is very small (short circuit) on this bus, there are two options, either the U402 MP2125 microcircuit itself burned out or something that sits on this bus ceramic capacitors ...
It is necessary to unsolder the choke L407 and check the resistance at both points relative to ground.

[Rennokas]

Re: Asus vg248qe purple light problem

And you need to measure the voltage at each choke relative to gnd, and not between them

Voltage between GND
L406 has 1.23v and 1.21v
L407 has 0.21v and 0.29v

Resistance
L406 has 300ohm and 300ohm
L407 has 1ohm and 1ohm

Removed the two caps and measured
L406 has 137ohm and 137ohm
L407 has 1ohm and 1ohm

L406 has 0.94v and 1.2v
L407 has 0.08v and 0.2v

[lotas]

Re: Asus vg248qe purple light problem

Which caps do you mean?

these

[Rennokas]

Re: Asus vg248qe purple light problem

0.4 Ohm is a short circuit, unsolder these two capacitors, which I soldered to the board and re-measure the resistance on the left choke

Which caps do you mean?

[lotas]

Re: Asus vg248qe purple light problem

0.91v between the chokes.

And you need to measure the voltage at each choke relative to gnd, and not between them

[lotas]

Re: Asus vg248qe purple light problem

0.4 Ohm is a short circuit, unsolder these two capacitors, which I soldered to the board and re-measure the resistance on the left choke

[Rennokas]

Re: Asus vg248qe purple light problem

What is the voltage across these chokes?
And what is the resistance between gnd. If the capacitor is short-circuited, the dc-dc converter U402 could burn out.

0.91v between the chokes. Right ones resistance is 144 ohm and left one 0.4 ohm.

[lotas]

Re: Asus vg248qe purple light problem

Seems like it does not get 3.3v on between 4 and 8. It gets only 0.19v

What is the voltage across these chokes?
And what is the resistance between gnd. If the capacitor is short-circuited, the dc-dc converter U402 could burn out.

[Rennokas]

Re: Asus vg248qe purple light problem

between 4 and 8 pin. should be 3.3v

Seems like it does not get 3.3v on between 4 and 8. It gets only 0.19v

[lotas]

Re: Asus vg248qe purple light problem

between 4 and 8 pin. should be 3.3v

[Rennokas]

Re: Asus vg248qe purple light problem

if there is a programmer, then you need to unsolder U8, read the contents from it (dump) and save, then write this dump.

Should I check voltage ? Seems like pin8 is VCC and pin4 is GND

[lotas]

Re: Asus vg248qe purple light problem

if there is a programmer, then you need to unsolder U8, read the contents from it (dump) and save, then write this dump.

[Rennokas]

Re: Asus vg248qe purple light problem

24C16RP is an eeprom, there is 25L1606 next to it, this is an SPI flash in it and the monitor's firmware is located.

How to get the latest firmware? On Asus site there is a driver with .inf, .icm and .cat files

[Rennokas]

Re: Asus vg248qe purple light problem

U8 marking ?

U7 is 24C16RP
U8 is 25L1606E (or smth, last letter is somewhat faded)

[lotas]

Re: Asus vg248qe purple light problem

On the back side there is one 24C16RP

Added pics of the other side aswell.

24C16RP is an eeprom, there is 25L1606 next to it, this is an SPI flash in it and the monitor's firmware is located.

[kasfamily]

Re: Asus vg248qe purple light problem

U8 marking ?

[Rennokas]

Re: Asus vg248qe purple light problem

Wanted to add that Windows 10 sees the display as "generic PnP". I was able to update driver from device manager to the latest from Asus site.