ASUS X555LD all voltage oscillating

[jasko_jacker]

Hi all,
I have an asus x555ld motherboard, when plug in the adaptor I hear a coil noise and when I measure 3.3V , 5V, 1.05V etc there is an oscillation from 0 to vmax.
thanks

[Djosla]

Re: ASUS X555LD all voltage oscillating

No boardview or schematics ?...Is 19v steady in 3.3/5v circuit...Also check current sense resistors in same circuit...If you don`t have schematics...find pwm datasheet so you can determine where are those resistors...

[meritosari]

Re: ASUS X555LD all voltage oscillating

Might be DC jack issue, try bypass by using cable another dc jack (ex. dc jack toshiba fit for psu universal/bench psu)

[jasko_jacker]

Re: ASUS X555LD all voltage oscillating

Thanks I try with no result after I have desolder the jump PJ8200 that is to P_+1.05VSUS_VIN_S
after that, the voltages return stable.
I have three asus mainboard with problem on +1.05 but I can not locate the exact component that is causing this problem.

[meritosari]

Re: ASUS X555LD all voltage oscillating

I would try flash bios.

[jasko_jacker]

Re: ASUS X555LD all voltage oscillating

I reprogrammed the bios, but with the same result, at this point I suspect that there is a problem of CE firmware, but I have not the programmer to IT885E last thing I look for (as has been suggested) it is to check PU8800 3.3V DC / DC 5V to see if there is an abnormal functioning.

[meritosari]

Re: ASUS X555LD all voltage oscillating

I would try flash bios.

I forgot to mention that I found similar symptoms on Quanta ZHK, and Asus X200MA, but in my case System ALW not fluctuating it was already steady, only on CPU core and 1.05 lines was fluctuating. I notice like tokin issue. I just re-flash the bios chips and it's works.

@jasko_jacker
Might be in this case, the boards (3 board on your bench ) have another issue.

[raizenn27]

Re: ASUS X555LD all voltage oscillating

hello there can you please post the bios dump that you used?coz i do have the same problem..thanks in advance

[Yupiua]

Re: ASUS X555LD all voltage oscillating

Hi all,
I have an asus x555ld motherboard, when plug in the adaptor I hear a coil noise and when I measure 3.3V , 5V, 1.05V etc there is an oscillation from 0 to vmax.
thanks

Hello friend I have a X555LD Rev 2.0 that has the brightness of the dark screen and I need the schematic to be able to find the brightness control circuit. Could you attach it?

thank you

[Yupiua]

Re: ASUS X555LD all voltage oscillating

Hello friend, I have a X555Dl Rev 2.0 that has the brightness of the dark screen and I need the schematic to be able to find the brightness control circuit. Could you attach it?

[meritosari]

Re: ASUS X555LD all voltage oscillating

Hello friend, I have a X555Dl Rev 2.0 that has the brightness of the dark screen and I need the schematic to be able to find the brightness control circuit. Could you attach it?

Schematic NO, boardview YES, see on post above

[tupacxxx]

Re: ASUS X555LD all voltage oscillating

I reprogrammed the bios, but with the same result, at this point I suspect that there is a problem of CE firmware, but I have not the programmer to IT885E last thing I look for (as has been suggested) it is to check PU8800 3.3V DC / DC 5V to see if there is an abnormal functioning.

good day sir can you give me step by step on how to flash the bios asus x555ld

[jasko_jacker]

Re: ASUS X555LD all voltage oscillating

it's simple :
1 - download a exact bios dump for your motherboard,
2 - desolder the bios chip , some programmers have a connector to program the bios onboard but
but don't always works.
3 - insert or solder the bios chip on your programmer adaptor
4 - if the bios chip is well recognised read it to make a copy
5 - load the new bios and start the programming
6 - if the verify it's ok solder the chip on motherboard
it's all

[kiraro]

Re: ASUS X555LD all voltage oscillating

Hello ,i have a mobo NEW70 LA-5891P ,3V and 5v oscillating (3,34v ~2,7v,5,02v~4,5v) and 19v become 8v ,no short on vin 19v when I remove pl26 the vin of 3v/5v circuit the 19v become stable but when put the inductor they become oscillating ,any one can help ,thank you ,it may be pu22 the cause?thank you

[jasko_jacker]

Re: ASUS X555LD all voltage oscillating

If you remove PL26 on page 46 (if I have the same pattern) you exclude PU16, this makes the identification of the problem more difficult.
In this cases, if there isn't an hot chip, it's not simple to detect the damaged chip or a component around it.
For example on X555LD there was an issue on the DC/DC converter which powered the GPU.
if there are, on motherboard , the jumpers that you see on schematic page 44 , we need
to individuate if the issue is on 3v branch or in 5v . For make this , remove one by one this jumpers on page 44:
1 - PJ8 and check if the issue remain, close jumper
2 - PJ6 and check if the issue remain, close jumper
Post the result

[kiraro]

Re: ASUS X555LD all voltage oscillating

If you remove PL26 on page 46 (if I have the same pattern) you exclude PU16, this makes the identification of the problem more difficult.
In this cases, if there isn't an hot chip, it's not simple to detect the damaged chip or a component around it.
For example on X555LD there was an issue on the DC/DC converter which powered the GPU.
if there are, on motherboard , the jumpers that you see on schematic page 44 , we need
to individuate if the issue is on 3v branch or in 5v . For make this , remove one by one this jumpers on page 44:
1 - PJ8 and check if the issue remain, close jumper
2 - PJ6 and check if the issue remain, close jumper
Post the result

Thank you jasko_jacker,
I fixed the problem of oscillating voltage; it was pu 18 faulty,
When I remove pu18 (LM393) all the voltage become stable, also i can power the mobo and it display fine on external monitor.
The new problem, when I put it again (pu18) all the voltage become unstable (first problem)( replaced with working one same result) .
my question is , the mobo work fine without pu18, I know it's stupid to removed and turn on the mobo that may cause others problem but I still curious lol ,I tried to replace it with a working one but same result , if I keep the mobo like that, without lm393 there be a risk ? Second question, why when I put it again all the voltage become unstable what that mean! , may be PACIN signal have a broken resistance ? Alternatively, something like that, because I solder two resistance PR297 and PR301 there was a bad connection with VIN (damage pad see picture) may be other damage pad? What do you think mister and thank you?
and if you can explain how lm393 work because without him pin 1 of pu 18 have 3.23 v and when i put it again it become 0.12v ,there be a problem no ?
without pu18 i found those voltages ;Pin1=3.23v,Pin2=3.29,Pin3=3.26,Pin 4=0,Pin5=9.04,Pin6=3.28,Pin7=5.23,Pin8=18.74.

thank you .

[kiraro]

Re: ASUS X555LD all voltage oscillating

I solve the problem it was another bad connection between vin and resistance ,every think work fine,thank you

[danon2]

Re: ASUS X555LD all voltage oscillating

Hello guys i have problem with mainboard model x555LD rev 3.3 (X555LJ)
I must recognize from schematics 2 parts.

PU9100 and R3031 because are damaged on the board what im busy with repair.

My motherboard don't recognize on that moment any hdd because no power on pin numer 36 from J6801

[EnricoS92]

Re: ASUS X555LD all voltage oscillating

Hi all,
I have an asus x555ld motherboard, when plug in the adaptor I hear a coil noise and when I measure 3.3V , 5V, 1.05V etc there is an oscillation from 0 to vmax.
thanks

Hi,
I have the same exact problem on my x555ld rev 2.0, how did you solved it?