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**Techtiger** · 11-04-2023, 03:33 AM

Re: Acer Aspire E5-574G - Not Powering On

(PR1: Resistance = ~84K. Voltage on Pin 1 = 6V (Correct and same as REGN). Voltage on Pin 2 = 0V (Incorrect should be ~3V, same as ACOK).
ii) PR4: Resistance = ~84K. Voltage on Pin 1 = ~0V (Incorrect should be ~3V, same as ACOK). Voltage on Pin 2 = 0V.)

ACOK must be +3V PR1/4 100K replace the resistors visually damaged for PQ22 remove it and test resistance again

**piernov** · 11-04-2023, 04:40 AM

Re: Acer Aspire E5-574G - Not Powering On

Missing measurements for other MOSFETs of the charging circuit, resistance to ground on main power rail and resistance across the current sensing inputs of the charger IC.

**novice1** · 11-04-2023, 08:20 AM

Re: Acer Aspire E5-574G - Not Powering On

Thank you both for the response. My apologies for posting the schematic and board view in the wrong place. I didn't fully understand the answers, and to avoid any confusions I have a few questions before proceeding as I'm new to this and don't want to damage the board.

1) You said "ACOK must be +3V PR1/4 100K replace the resistors visually damaged". But PR1/4 both don't look visually damaged at all.

I can confirm that I have a spare practice board from Acer E5-575 that I bought on ebay. PR1/4 measure 84K on that practice board as well. So my original board (574g) and the practice board (575g) both measure PR1/4 as 84K. So not sure if PR1/4 are damaged. Should I still replace those resistors even though they do not appear to be visually damaged, and the resistance is pretty good (84 Kilo Ohms).

In case I have to replace them, can you guide as to the best place to buy these resistors at. Any links will be helpful as I don't know which ones look exactly the same.

2) For PQ22, in case above is true i.e. after replacing the resistors then I should de-solder PQ22 and post the resistance results for PQ22. Is this right?

These steps need to be performed in the above order?

This question is for Piernov's response. I did post the measurements of the MOSFET PQ22 above (if that is what you meant), and only see one MOSFET. Posting the measurements for PQ22 MOSFET again.

PQ22: MOSFET AON6414Al
i) Voltages:
Drain = 19V (Pins 5, 6, 7, 8)
Source = 0V (Pins 1, 2, 3). This is incorrect, and should be 19V.
Gate = 0V (Pin 4). This is incorrect, and should be 25V.

ii) Resistances in mega ohm
Drain to Source = ~0.85M
Drain to Gate = ~ 5.5M
Gate to Source = ~4.3M

Are there any other MOSFETs I'm missing? Also "how do I measure resistance to ground on main power rail and resistance across the current sensing inputs of the charger IC". Is there a guide to this that I can read so that I post my results.

The resistance between Pin 1 or charging IC PU5 and ground is ~0.6 ohms. If that is what you meant. I measured this touching my black probe to the ground and my red probe to Pin 1 of charging IC PU5.

**novice1** · 11-04-2023, 11:27 AM

Re: Acer Aspire E5-574G - Not Powering On

Piernov after reading your guide further and delving into more technical details. Hopefully I understood stuff correctly. I'm posting the following resistances between ground and Pins 1 and 2 of charging IC PU5 (BQ24780S)

1) Resistance = ~0.51 ohms, Between ground and Pin 1 (ACN)
2) Resistance = ~0.51 ohms, Between ground and Pin 2 (ACP)

I measured the above by touching my black probe to the ground and my red
probe to Pin 1 and then Pin 2 of charging IC PU5.

As I mentioned in the comment above I have a spare practice board (Acer E5-575G). Schematic for that practice board is not exactly same but it has the same exact charging IC PU5 (BQ24780S). On that practice board, the above resistances between ground and Pins 1 and 2 are in Mega ohms (~1.65M) for charging IC PU5.

Resistance between ground and Pins 1 and 2 on original board (Acer - 574G) is in ohms but on practice board (Acer - 575G) is in Mega ohms. Is the resistance on Pins 1 and 2 too low on original board. Please let me know what else to test or replace, and how to proceed.

**Sephir0th** · 11-04-2023, 04:13 PM

Re: Acer Aspire E5-574G - Not Powering On

This is one of the most common and fortunately easy to figure faults. A shorted main power rail. You need to check all inductors present of the board for a similar value compared to GND. If nothings turn out, you probably don't have to deal with a so called high-side short but a shorted capacitor. Voltage injection is the way to go from there. Greetings to piernov *wink*

**novice1** · 11-04-2023, 05:15 PM

Re: Acer Aspire E5-574G - Not Powering On

After reading the Piernov's guide a hundredth time today, found a fault in one of my previous readings and would like to correct it. Re-did all my tests again. I think I have found a faulty resistor. In my comment 1, I said the following:

"1) (CMSRC) PR166: Resistance = ~4K. Resistance value is correct. Voltage on Pin 1 = ~0V, Pin 2 = ~0V. Both voltages are incorrect and should be 19V."

This statement is not true. PR166 and PR165 are so close to one another that I got the PR 166 reading wrong. My apologies for the mistake. Below is the correct reading.

(CMSRC PR166: Resistance = ~ 0.5 ohms. This is incorrect. Correct Resistance should be 4K. And it beeps in continuity mode while PR165 doesn't.

According to Peirnov's guide (2.1.7. Damaged passive component), "One possible issue would be the gate resistors for the DC-in MOSFET, as well as the resistor connected to CMSRC pin when it is present, so you can always check them if you're in doubt."

This is exactly what is happening here. PR165 which is the gate resistors for the DC-in MOSFET with one side connected to ACDRV pin is showing the correct resistance of 4K. But PR166, the resistor connected to CMSRC pin is showing a wrong resistance of ~0.5 ohms. Looks like the main rail is shorted because of this resistor.

I'm not saying this is the only problem there could be other issues as well. But to get to those issues, PR166 has to be fixed first.

Before I ask further questions and check all inductors, should I replace PR166 first. If so from where can I buy a 4K resistor? Is this the same as "0402" resistor. I see some links on amazon. Please let me know and I will proceed accordingly.

**Sephir0th** · 11-04-2023, 06:26 PM

Re: Acer Aspire E5-574G - Not Powering On

My friend, you're making wrong conclusion because of missing knowledge and missing experience.

There is no way PR166 could cause a shorted main power rail since it has no natural connection to GND. Also a resistor almost never fails shorted. They fail open. So I have to strongly doubt about your measurement, maybe even about whether you're measured the correct resistor. Sometimes it is hard to differentiate between the various resistors on the same rail.

**novice1** · 11-04-2023, 07:39 PM

Re: Acer Aspire E5-574G - Not Powering On

That is very true. I'm definitely not knowledgeable and missing experience. That’s why I came here, and am willing to learn and give it a shot. One of the reasons I bought the practice board, and spent time learning the schematic.

I understand your point and used the wrong technical terminology. Thanks for the correction. It might not be called a shorted main power rail but I'm positive that resistor PR166 is showing a wrong value. I wore much bigger lens and re-tested everything again before posting this comment. I can confirm two things:

1) With the multi meter in Resistance mode, PR166 still reads !0.5 ohms, and PR165 reads 4K ohms. All other readings (voltages and resistances) are also the same as in comment 1
2) With the multi meter in Continuity mode, PR166 beeps, and PR165 does not beep and says 0L.

To be precise, I performed the above tests by putting the black probe on end of the resistor and the red probe on the other end of the resistor. Maybe I'm doing something incorrect here.

I have attached 2 pictures. They both are the same pics and lighting is pretty good. But in Pic 1 I have pointed out PR166 with a box in red paint. You can see the below in Pic1.

On the left side of PR166 is PC115. Below PC115 is PC116, PC119, and PC122. All of them are horizontal.
On the right side of it is PR165. Next to PR165 is PR168. Both of them are vertical. You can see there is no PR167 between PR165 and PR168 like I pointed out in comment 1. Next to PR168 is PJ2 (Power Jack). You can see the slight white plastic in the picture.

I think Piernov’s guide point still holds true for this case that one of the possible issues is the resistor connected to CMSRC pin when it is present. It appears that in this case it is present and is PR166. I’m not sure what the technical name is for that. From your earlier comment it looks it that possibly some other part is bad and that is why PR166 is showing a wrong value.

If you think that resistor is called something else and if that’s not what is wrong, please let me know what I’m missing and I’m willing to test that and proceed accordingly. Thank you.

Attached Files

**Sephir0th** · 11-05-2023, 02:45 AM

Re: Acer Aspire E5-574G - Not Powering On

Okay, confirmation necessary: Lift PR166 from at least on pad of the PCB and perform the same measurement again.

My bet is that the Resistor out of circuit won't read 0 Ohms anymore other than the CMSRC Pin at the charging controller itself.

General rule if a resistor is in question is to test it out of circuit like explained above.

**mcplslg123** · 11-05-2023, 03:01 AM

Re: Acer Aspire E5-574G - Not Powering On

To clear the confusion,you should measure resistance to GND on any pin of PR213-That will tell us whether your 19V rail is shorted or not. You have correctly identified PR166 and it should be 4K.PR166 one end is connected to 19V rail and hence it may misguide you as shorted. However, you can measure the resistor out of circuit and repeating the resistance to GND on both pads of PR166 to be sure its the resistor or its the pad on PCB which is shorted. But first Resistance to GND on PR213 please.

**novice1** · 11-05-2023, 12:04 PM

Re: Acer Aspire E5-574G - Not Powering On

Thank you both for answering. Sephir0th I did not pull out PR166 yet because I agree with you that probably some other component is bad and probably there is short to ground on the main rail. I want to test more before I jump the gun.

So based on mcplslg123 advice I performed below tests on PR213, and some other components connected to the main power rail. I also attached a pic of PR213 for confirmation.

All of the below tests measure resistance to the ground on the main power rail. To be precise I did so with the multi meter in the resistance mode and touching the black probe to the ground, and touching the red probe one by one to the pins of below components. If I used the wrong terminology or performed the wrong tests please correct me, and I will redo all the tests again.

Touched the black probe to the ground and the red probe one by one to both ends of resistor PR213.

1) With the multi meter in Resistance mode
Resistance = ~0.5 ohms (Pin 1)
Resisatnce = ~0.5 ohms (Pin 2)

2) With the multi meter in Continuity mode, Pin 1 and Pin 2 both beep

I also performed the same tests on my spare practice board which also has PR213. In resistance mode, Resistance is in Mega Ohms (Fluctuates but stays in Mega ohms). Moreover in the continuity mode neither of the Pins 1 and 2 beep on the practice board.

Pic of PR213 is attached. Pic2 is the same but has the components I ran my tests on circled. I have circled all 3 components (PR213, PQ22, PC136) in Pic2. PR213 is in red square. PQ22 and PC136 are in blue square.

PR213 looks like a different kind of resistor and there are 3 letters on top of it "R01". Not sure if the last two are numbers zero and one or alphabets ‘O’ and ‘I’. Moreover from the Pic by looking at the left side of PR213, you can also see that PR209 and PR210 are not present on the board. You can also see MOSFET PQ22 on top of it with letters 6414A. Below PQ22 is a small capacitor called PC136.

It looks like I’m not getting any VA2. Another observation and I might be wrong here so you can correct me. This is the test to measure resistance and continuity on any Pin that gets VA2. From the schematic and board view below components get VA2.

1) MOSFET PQ22 on Pins 1, 2, 3
2) PC136 on Pin 1
3) PR213 on Pin 1
4) PR166 on Pin 1

With the multi meter in the resistance mode and touching the black probe to the ground, and touching the red probe to the pins of below components. Basically resistance to ground for these components.

1) PQ22:
Source Pins 1, 2, 3; Resistance = ~0.5 ohms to ~0.6 ohms.
Drain Pins 5, 6, 7, 8; Resistance is in Mega ohms (~0.85).
Gate Pin 4: Resistance = ~4 Kilo ohms.

2) PC136:
Pin 1, Resistance = ~0.6 ohms
Pin2, Resistance = ~4 Kilo ohms

With the multi meter in the continuity mode and touching the black probe to the ground, and touching the red probe to any Pin that is connected to VA2, the multi meter beeps. It does not beep on the other pins of those components.

MOSFET PQ22: Pins 1, 2, 3 beep but not others. Pins 1, 2, 3 are connected to VA2.
PC136: Pin 1 (VA2) beeps but Pin 2 doesn’t
PR166: Both Pins beep but Pin 1 is connected to VA2

As a note on the spare practice board, for components PQ22 and PC136 resistance on all Pins is in several Mega ohms, and on continuity mode all pins of PQ22 and PC136 don’t beep at all.

From Piernov’s guide point 2.1 (HPB Buck topology), I think in my case PQ22 is the “2nd DC-in MOSFET” and PR213 is the current sensing resistor. I’m not sure which one is correct, and what component is faulty as it could be any of the faults specified in 2.1.2 (Short to ground on main power rail), 2.1.3 (Shorted DC-in MOSFET), 2.1.4 or something else. Not sure which component is the problem PQ22, PC136, PR213 or something else. Does this tell you anything if the 19V rail I shorted or not.

If you think any of the above readings and explanation appear incorrect, I will redo all the tests. Please let me know how to proceed further. Thanks

Attached Files

**mcplslg123** · 11-05-2023, 10:56 PM

Re: Acer Aspire E5-574G - Not Powering On

Going by the resistance to GND reading on current sensing resistor PR213,you have +19V rail shorted to GND.

You need to de-solder PR213 and i'm sure pin2 of PR213 is shorted to GND. You need to inject 1V/5A on pin2 of PR213 with a dc supply and see what's getting hot. Ofcourse you need a dc supply/short killer to find the shorted component.

PS: No point troubleshooting any aspect unless you fix this +19V rail short.

**novice1** · 11-06-2023, 10:32 AM

Re: Acer Aspire E5-574G - Not Powering On

Thanks again. This is very helpful and I will do the above test but currently I don't have a variable DC power supply. I plan to order one today and should get it by Thursday or Friday. I have a few questions just for my understanding so as to learn.

1) For PR213, you chose Pin 2(VIN) and not Pin 1(VA2) to inject voltage because some components with VIN on one pin have the other Pin connected to GND while this is not the case for VA2. For example component PC141 has Pin1 as VIN and Pin2 as GND. But with all components with VA2 on one Pin have none of the other Pins as GND.

2) As you know, I have never done this so saw a few videos as how to inject voltage. Just to confirm, first I will de-solder PR213 using the Hot Air Gun, and clean that pad. Let the motherboard cool down for 20 minutes. Then get 2 jumper wires. Solder one jumper wire to the GND on the mother board and solder second jumper wire to the Pin 2 of PR213. Then connect the other ends of those soldered jumper wires to the DC power supply using banana clips. Inject 1V/5A and see which component is getting hot by touching the motherboard with my hand.

How long do I need to inject voltage, just in case it takes me longer to inspect and figure out which part is getting hot. Like 30 seconds and then pause if I can't figure out which part is getting hot. Then let the motherboard cool, and start the process again after a few minutes till I find the part getting hot.

Since I will not be able to do this until Thursday or Friday depending on when I get the power supply delivery, please let me know if I need any other parts related to the DC power supply.

**mcplslg123** · 11-06-2023, 11:06 PM

Re: Acer Aspire E5-574G - Not Powering On

The method of injecting voltage is well understood by you. You need to check which pin of PR213 is shorted to GND(My assumption is pin2 but i may be wrong).So voltage needs to be injected on the pin which is shorted to GND.

You can keep it injected unless you feel something hot. Dont disconnect the voltage injection as you may never feel the hot spot. Keep it injected unless you feel something hot.

Newer SOC motherboard wont be very hot and you need to feel which area is slightly warm then the other part of motherboard and then narrow down the search for faulty component. It could be a capacitor/mosfet or even a PWM IC.

Motherboard wont be damaged with voltage injection for long time as long as you dont exceed 1V limit. Any higher voltage injection is risky.However, you can go upto 10Amps if your dc supply supports it.

**novice1** · 11-07-2023, 09:23 AM

Re: Acer Aspire E5-574G - Not Powering On

Thanks for the explanation above. As I wait for the power supply, investigated this further and have a few more questions. Might have found something interesting so wanted to share as it could narrow down this problem even further. In this new test, checked all the inductors on the board to see if any inductor is lower than 1 Ohms. This is again based on Piernov's guide point 2.1.2 (Short to ground on main power rail). If I used the wrong terminology or performed the wrong tests below, please correct me.

I did so with the multi meter in the resistance mode. Then touching the black probe to the ground, and touching the red probe one by one to the pins of all inductors. Below are my readings.

1) PL1 = ~3 Mega Ohms (Fluctuates between Mega Ohms)
2) PL2 = ~15 Ohms
3) PL3 = ~15 Ohms
4) PL4 = ~16 Ohms
5) PL5 = ~19 Ohms
6) PL6 = ~45 Kilo Ohms
7) PL7 = ~21 Ohms
8) PL8 = ~21 Ohms
9) PL9 = ~10 Ohms
10) PL11 = ~115 Ohms
11) PL14 = ~2 Kilo Ohms
12) PL15 = ~0.6 Ohms
13) PL16 = ~29 Kilo Ohms
14) PL6012 = Fluctuates between Kilo Ohms and Mega Ohms
15) PL6013 = Fluctuates between high Kilo Ohms and Mega Ohms

PL15 is clearly less than 1 ohm. So I'm guessing the short is somewhere in that area of the motherboard. This inductor is on Page 35 of the schematic. PL15 appears to be connected to "+1.35VSUS" rail. Several components to the left and right of PL15 are connected to the ground. PC268, PC275 to the right. PC250, PQ31 to the left. IC PU15 is also connected to the ground. Any of these components connected to the GND on Page 35 could be shorted right? Not sure if there is a way to narrow this down further.

Want to share another important detail since it's a high possibility that the short could be on the +1.35VSUS rail. It appears that +1.35VSUS rail is connected to the RAM. There are 2 RAM slots on the motherboard. I can confirm that I did add a new RAM stick on the slot next to where PL15 is located (JDIM2 in board view). After doing so, I remember the laptop screen flickering and going dim sometimes in the beginning so I thought it was probably a screen issue. After a month it didn't power on at all. As a note I didn't use it much during that time. Was that newly added RAM part faulty and caused a short?

**mcplslg123** · 11-07-2023, 11:42 PM

Re: Acer Aspire E5-574G - Not Powering On

Desolder PR213 & PL15. Now check continuity between shorted pad of PR213 to PL15(both pads). If the meter is buzzing,then definitely 1.35V rail is shorted.

Btw, measure the resistance to GND on PL15 coil
01.With ram stick inserted
02.Without ram stick.

This will give us an idea whether any of the ram stick is shorted or 1.35V rail is shorted.

PS: No power should be attached while measuring resistance to GND.

**novice1** · 11-08-2023, 09:54 AM

Re: Acer Aspire E5-574G - Not Powering On

Below are readings for resistance to GND on PL15. No power was connected. With the multimeter in resistance mode, and black probe to the ground, and touching the red probe one by one to the pins of PL15.

With RAM stick, resistance = ~0.4 Ohms
Without RAM stick, resistance = ~0.4 Ohms

Same in both cases and less than 1 ohms.

I haven't de-soldered anything yet. Power supply should be here by tomorrow. Shouldn't I wait and do voltage injection by only removing PR213. I mean go with the original plan. Or do you want me to de-solder PL15 as well.

**mcplslg123** · 11-09-2023, 03:58 AM

Re: Acer Aspire E5-574G - Not Powering On

I'll suggest to desolder PL15 and check resistance to GND on both pads.Recheck resistance to GND on PR213(while PL15 is removed)-is the resistance quite high now?

**novice1** · 11-09-2023, 06:09 PM

Re: Acer Aspire E5-574G - Not Powering On

De-soldered PL15 per your suggestion. I did not de-solder PR213.

Below are readings for resistance to GND on both the pads of PL15. With the multi meter in resistance mode, and black probe to the ground, and touching the red probe one by one to the pads of de-soldered PL15.

1) Pad 1 (51216_SW), Resistance = ~2 Mega Ohms (fluctuates in several Mega Ohms)
2) Pad 2 (+1.35VSUS), Resistance = ~0.4 ohms

Multi meter in continuity mode only beeps on Pad 2 of PL15, and does not beep on Pad 1.

Reading for resistance to GND on the pins of PR213.

1) Pin 1 (VA2), Resistance = ~2.5 Mega Ohms (fluctuates in several Mega Ohms)
2) Pin 2 (VIN), Resistance = ~2 Mega Ohms (fluctuates in several Mega Ohms)

You’re correct resistance is very high now. Moreover the multi meter in continuity mode does not beep on any pins of PR213.

Does this mean the +1.135VSUS rail is shorted since that is the only pad that has a resistance of less than 1 ohms and beeps in continuity mode?

According to the board view below components are connected to the same side as inductor on the +1.135VSUS rail:

1) PC268 (Pin 2)
2) PC275 (Pin 1)
3) PU15 (Pins 2, 9)
4) PC235 (Pin 2)
5) Bunch of Ram Pins on both sticks JDIM1, JDIM2
6) R679 (Pin2). I do not see this component on my board
7) Q35 (Pin2). I do not see this component on my board.

There is also a lot of components mainly capacitors connected +1.35VSUS on the other side of the board as well. There is a black tape like extra protection that covers them. Upon visual inspection nothing looks worn out on both sides of the components connected to the +1.35VSUS rail. But I’m no expert because something has to be wrong. Probably on those components is short at the top or bottom of the board.

Should I inject voltage on pad 2, I mean if you think +1.35VSUS rail is shorted. If yes should it be the same like 1V/5A or some other input.

I also have a question about voltage injection. Is it easier to figure out which part is getting very hot by touching with hand or multiple parts will get hot and it will get confusing? That's what I'm really concerned about. How long does it take for the shorted part to get hot (1 to 2 minutes or longer). It will be nice to get an idea of some of these things.

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