Acer V5-531 Does not turn on

[stingerchamp]

Re: Acer V5-531 Does not turn on

Just a little help if you don't mind

Keep going and learning just like me

Pu 4103 works like below

Pin 16---Vin input DC batout 19v or battery voltage
Pin 1--- entrip is internal input
Pin 2 ---- entrip is internal input

Both entrips should be ok to ic to be ok

Pin--- 8 and pin---17. Vreg3,5 both linear drive outputs
Means pure DC voltage outputs no switching

Both or 3vreg should be available to super Io chip to work

Always look at power sequence flow at schematic

First check 3v rtc_vcc then check rtc_srtc and so on
Enc pu4103 pin 18 is input check voltage


Now comes s5_on signal which is output of kbc

As per power sequence it should be high when good
I do not get how this signal is dropping to perform
Maybe logic is different here hmm

Ecrst# should be 3.3v
3D3V_AUX_KBC should be 3.3v

Check r2780 from there gate is coming at pq 4101 for 5v entrip 0

At good board check
Pin 14 and pin 104 ,109 and compare it with bad board at kbc

If pu4103 is heating remove it at the earliest


Answer pin 19 is gate supply for low sde mosfet

Pq4101 gate is not opening you both are right

[Sephir0th]

Re: Acer V5-531 Does not turn on

Jo"As I see it there is 3.3V in places where it should be 0V"

You mean PIN1 on D3601? Double Check that Please. I'm Not really Sure how to Interpret this Signal correct, But i guess, 3,3V should be okay. Maybe the Laptop "thinks" It is on.

Additionally to the informations and advise from Stingerchamp (your Help is Very Welcome! ) let us sum Up.

PU2701 PIN 14 is an Output from the SIO
PU4103 PIN1 & 6 are Inputs from PQ4101

Nothing is Missing before S5_Enable
All components seem to be okay on this Rail, except...

That PU4103 is getting hot, is a really new and important Information for me and Points to a short somewhere around this IC, e.g. to Pin 19. I believe 5V are Not normal, because this Pin Drives a Low-side N-Channel Mosfet, which creates the 5V_PWR Rail. Afaik even when the Laptop is powered on, there should be a lower voltage. Did you double-checked this? When the Laptop is Off, there should be 0V as measured on the "good" Board.

Unfortunately it doesnt't make Sense to me, that there is some coherence beetween Missing S5_Enable and an internal shorted IC beetween Gate and whatever. But Maybe Someone Here can Provide us a logical explanation.

However, If all this is true, you have to replace PU4103 and If you're Lucky, the S5_ENABLE comes Back to Life.

[Mad Capper]

Re: Acer V5-531 Does not turn on

In response to stingerchamp:

Both entrips should be ok to ic to be ok

They are not. BAD board meaures 0.9V on pin 1 and 6, not 5V. Therefore, you would say that PU4103 is bad, correct?

Pu 4103 works like below

Pin 16---Vin input DC batout 19v or battery voltage
Pin 1--- entrip is internal input
Pin 2 ---- entrip is internal input

I believe you mean pin 1 and 6, correct? Are you saying this 5V is created internally in PU4103 and not from an external source? And this 5V is then output to PQ4101 pins 3 & 6?

Both or 3vreg should be available to super Io chip to work

All pins labeled 3D3V_AUX_KBC on and surrounding Super I/O have 3.3V

Ecrst# should be 3.3v
3D3V_AUX_KBC should be 3.3v

They are.

Check r2780

I do not know if the slight difference on pin 2 has any significance.

GOOD R2780..........BAD R2780
......9.88K.............9.88K
1......3.38V............3.6V
2......3.05V............3.358V

Pin 14 and pin 104 ,109 and compare it with bad board at kbc

Am I correct to assume by "at kbc" you mean U2701?

...GOOD U2701..........BAD U2701
Pin 14......0V.............3.3V
Pin 104.....3.3V...........3.3V
Pin 109.....3.04V...........3.35V

Again slight difference on pin 109.

Does this indicate internal short in U2701?

If pu4103 is heating remove it at the earliest

I would need to order one from China to replace it. And hope my lack of good tools and skill can actually replace it.

Out of curiosity I tested the pins of PU4103 that differ between the two boards to see what the readings were when the GOOD board was switched on. Again, as in other tests when ON the GOOD board has the readings or close to the BAD board when OFF. I am having a hard time understanding why and do not know if there being opposite is just coincidence. For pins 1 and 6 of the BAD board when the power button was pressed you could see the voltage drop, it was more noticeable on pin 6.

GOOD OFF PU4103..........GOOD ON............BAD OFF PU4103..........BAD Power Button Pressed PU4103
1....5V....................0.8V.....................0.9V......................................0.88V
6....5V....................0.8V.....................0.9V......................................0.88V
12...0V....................1.07V....................0V........................................0V
18...3.3V..................5V.......................3.3V......................................3.3V
19...0V....................3.3V.....................5.04V.....................................5.04V


In response to Sephir0th:

3.3V is present where there should be 0V in more locations than just D3601 pin 1. The following is correct.

GOOD D3601..........BAD D3601
1...0V...................3.3V
2...0V...................0V
3...3.3V.................3.3V

Because of these readings and the fact that D3601 tests good in diode mode is this another indicator that U2701 is shorted internally? Thus the 3.3V on U2701 pin 14 where it should be 0V?

Maybe the Laptop "thinks" It is on.

This is how I interpret having readings on the BAD board when they should be 0V as the GOOD board indicates. I do not know if that is even a possibility. I have heard the term frozen BIOS before but as I am pretty sure the BIOS is separate on this so I do not think that would apply here. Can this happen to a Super I/O

PU2701 PIN 14 is an Output from the SIO
PU4103 PIN1 & 6 are Inputs from PQ4101

If U2701 pin 14 is output and should be 0V why is it 3.3V? Does U2701 have internal short or is 3.3V being fed back to this point, from where? An internally shorted U2701 is the only option I see as its pin 14 feeds PQ4101 Gate pins 2 & 5 which should be 0V but are 3.3V.


If the following is true :

Pu 4103 works like below ...
Pin 1--- entrip is internal input
Pin 2 ---- entrip is internal input

then I do not see how

PU4103 PIN1 & 6 are Inputs from PQ4101

could be true also. Remember this all when everything is off and plugged in.

Something has to come first. Either PU4103 pins 1 & 6 outputs 5V to PQ4101 pins 3 & 6 OR 0V output from U2701 pin 14 goes to input PQ4101 Gate pins 2 & 5 and somehow causes pins 3 & 6 to have 5V which then outputs to PU4103 pins 1 & 6. I am of the opinion that 5v outputs from PU4103 to PQ4101. Please help clarify this for me.

Are all these problems and incorrect readings on the BAD board caused only by a bad PU4103? Or is U2701 bad also?

That PU4103 is getting hot, is a really new and important Information

Not new information, this was mentioned in my first post, but now we are all on the same page.

Afaik even when the Laptop is powered on, there should be a lower voltage.

Correct, see newly added comparison above.

Yes, I am hoping that replacing PU4103 is the only problem, but need more clarification about potential problem with U2701. I do not have the tools or skills for PU4103 let alone the 128 pin U2701, but the smaller IC would be easier. At least it is not a BGA.

[stingerchamp]

Re: Acer V5-531 Does not turn on

If you see function diagram at datasheet

Pin 1 and 6 are entrip1,2 are attached to current source 10 u ampere via vreg5 and same to entrip2

There you see 150 k ohm resistor attached to control entrips

Now you calculate voltage
V= current X resistance

V= 10 micro amp X 150k = 1.5volts

Range is 0.5 to 3.5

Let's see our motherboard

Pq4101 is connected with entrip pins

Entrips need ground to apply ohms law

Pq4101 provides ground and we have a 88kohm resistor with pq4101

Let's calculate

v= 10 micro amp X 88 k ohm = 0.88 v within range

V =. 0.8 v for good board for entrip 2

For entrip 1

V= 10 micro amp X 84 k ohm= 0.84v so good

When both entrips get ground via pq4101being on
Then resistor will attach with entrips and above result we get.

Who turns on pq4101 that is s5_enable and 3D3V_SRC_EN

That is why I said check r2780 and pin 104 and pin 14 of kbc if it is getting 3.3 v and reached pq4101 and still pq4101 not on then remove pq4101


Now to make sure I am right but do at your own risk

With adapter only and do not press power button

With tweezers provide ground to entrips by shorting pin 1 and 6 of pq4101 and pin 3 and pin 4

It will give ground to entrips and resistor will attach and you get voltage at entrips in range


Why not working

Remember entrips connected internally to vreg5 and if voltage at entrips reach above 4 it will shut down


If entrips still out of range replace ic , 10micro amp source inside ic is damage


First step

Entrip 1,2 will enable ic

Second step

En pin 13 required high to generate ldo supplies and vref

Third step

Enc :pin18 required high to start switching MOSFETs inside ic to generate switching supplies for example last outputs of ic





Too much information ��

[Mad Capper]

Re: Acer V5-531 Does not turn on

Thank you for the explanation.

When both entrips get ground via pq4101being on
Then resistor will attach with entrips and above result we get.

If this is so then the readings, e.g. the 3.3V on U2701 pin 14, 0.9V on PU4103 pins 1 & 6, 3.2V on PQ4101 pins 2 & 5 etc., I am getting would indicate that even when off the BAD board is actually on. Some of the readings that don't make sense then are because the board is potentially not actually off and therefore I cannot get those readings. Does this mean that the board is on? Why and how is the board on? And how do I turn it off?

There are other readings that do not follow this theory. Therefore I do not know if it is true.

I don't think I am willing to remove PQ4101 for the test suggested.

Who turns on pq4101 that is s5_enable and 3D3V_SRC_EN

That is why I said check r2780 and pin 104 and pin 14 of kbc if it is getting 3.3 v and reached pq4101 and still pq4101 not on then remove pq4101

I think it is only S5_ENABLE turning on PQ4101. The orange dashed line block labeled "EC Change" "Option for non-IOAC" I believe applies to my board. I do not get 3.3V on either board at pin 2 of PQ4101 when off and testing continuity pin 2 & 5 are connected.

Pin 104 of U2701 has 3.3V on both boards. Pin 14 should be 0V when off and 3.3V when on according to GOOD board, but is 3.3V for BAD board when off.

If the first thing that needs to occur before anything else, PU4103 or PQ4101 etc., is S5_ENABLE from U2701 pin 14 goes from 0v to 3.3V when the power button is pressed then again it seems to be that the board is stuck on. I am wrong in thinking this?

[stingerchamp]

Re: Acer V5-531 Does not turn on

Don't get confused

I explained step by step working of ic using data sheet and how your motherboard ic will get inputs and which range is acceptable check your readings you are getting 0.8v at good board and 3.3v for s5_enable is mandatory to ic to work
It is a signal from kbc to start S5 state or working

3v,5v available o. Some boards before button pressed and in some after button pressed
Because it depends on this signal and logic


If you don't know

Know you know general information

S5 state means when adapter plugin only usually , ic inputs voltage are available

S3 means when power button pressed and ram section is on and sus voltage is available

So means when display is on are CPU fan running or full working, all sus supplies convert into run supplies

Obviously without adapter plugin you will not find voltage on board except CMOS cell

So when adapter plugin only and button pressed you will have these voltage value on pq4101

We are working in S5 state currently,

s5_on should be 3.3v at pq4101 to turn on pq4101 mosfet

N channel mosfet so need high supply at gate

I explained you complete circuit

One more thing

In some boards EC_on or s5_on signal directly enable ic and in some boards it is first connected to mosfet and then indirectly reach ic

[Mad Capper]

Re: Acer V5-531 Does not turn on

Unfortunatley, I am confused. I understand all that you have said. I am aware of S states. What I do not understand is why when off my BAD board has many of the voltage readings as though it were actually on.

3.3v for s5_enable is mandatory to ic to work
It is a signal from kbc to start S5 state or working

I understand this and follow start up process and schematic. Why does KBC already have 3.3V on pin 14 when only plugged in and no button pressed? If 3.3V is already there when I plug in the power why does the motherboard not start automatically? Are all the problems from PU4103? I could understand that the failure to start is because PU4103 is bad but I cannot figure why if that were true would I have 3.3V immediately when I plug it in when no button pressed to signal to KBC to output 3.3V on pin 14.

3v,5v available o. Some boards before button pressed and in some after button pressed
Because it depends on this signal and logic

On this board the main 3V and 5V comes on after the power button is pressed as verified at PT4101 and PT4102 on GOOD board.

So when adapter plugin only and button pressed you will have these voltage value on pq4101

The power button does NOT need to be pressed for me to get the correct voltages on PQ4101 as thought the motherboard were actually on. This is what is confusing me.

s5_on should be 3.3v at pq4101 to turn on pq4101 mosfet

N channel mosfet so need high supply at gate

Yes, Gate of PQ4101(pin 2 & 5) should be 3.3V when power button is pressed. 3.3V is coming from U2701 pin 14 without the power button is pressed? The problem is on the BAD board in S5 state it already has 3.3V in many locations that should be 0V but it does not actually turn on.

The question I have is why? Is it U2701 that is bad or PU4103 or both?

[stingerchamp]

Re: Acer V5-531 Does not turn on

Leave everything

Focus on s5_on available at kbc before power button pressed or after?

Should be 3.3v on both boards

at bad board check voltages at pq4101
Without power button pressed

It will clear your confusion

Off means adapter plugin only?

Maybe your power button is faulty
Remove button and start with connector pin short method
Check voltage at connector goes zero or not

[Mad Capper]

Re: Acer V5-531 Does not turn on

Focus on s5_on available at kbc before power button pressed or after?

By "at" what pin do you mean? If pin 14, S5_ENABLE, this is the readings. If not pin 14 what pin should I measure at?

........GOOD OFF U2701......GOOD ON U2701.........BAD OFF U2701
Pin 14...............0V.........................3.3V.......................3.3V

GOOD OFF PQ4101 ......GOOD ON PQ4101.............BAD OFF PQ4101
1.............GND..........................GND........................GND
2.............0V............................3.3V........................3.3V
3.............4.73V........................0V...........................0V
4.............GND.........................GND........................GND
5.............0V...........................3.3V.........................3.3V
6............4.97V........................0V...........................0V

Sorry, I am still confused. I see no reason, or do not understand the reason, that when the BAD board is off I am getting the same readings as when the GOOD board is on. I follow what you are saying and it makes sense looking at the GOOD board but I do not know why the BAD board is acting like it does. Again, is it a bad PU4103, U2701, both or something else?

Yes, when I say OFF I mean only AC adapter plugged in, power button/ribbon cable attached to motherboard and power button not pressed. There is nothing else attached to the board. When I say ON I mean when I press the power button and the front LED turns on and fan starts to spin.

I have tested the BAD board power button/ribbon cable on the GOOD board and it works fine. The GOOD board power button/ribbon cable does not turn on the BAD board. I have tested the button and cable and they act the same. Shorting PWRCN1 pin 3 to ground works fine on GOOD board but does not work on BAD board.


Yes, at PWRCN1 when button is pressed Pin 3 goes from 3.3v to 0V.

[stingerchamp]

Re: Acer V5-531 Does not turn on

Both but we have to check one by one

You understood right

[Mad Capper]

Re: Acer V5-531 Does not turn on

Yes, I understand checking one by one to accurately diagnose the problem and I thank you for your assistance.

So it is your opinion that both U2701 and PU4103 need to be replaced, correct?

I was hoping that U2701 was still good because it will be even more difficult for me to replace then PU4103 which will be a challenge also.