Re: Laptop died - Purism librem15
Thank you for the precious suggestions.
I think I will need time, probably days, before I could test my board in the way you suggested me.
Before I will be able to do that, I must purchase myself the equipment currently do not have.
Before the greetings, I want to ask you again about the coil.
I understand that just a picture can't be enough to figuring out a complex circuit defect.
But perhaps you considered something I do not get when you decided that the upper left coil low resistance was not an alarm...
handle
Member
Last Activity: 06-21-2020, 10:41 PM
Joined: 04-06-2019
Location: Rome
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Re: Laptop died - Purism librem15
Thank you for the kind answer.
I will investigate your suggestion during the day, hopefully.
In the meantime, can you please tell me which is the reason you didn't consider the low resistance on the coil near to the power button?
(In the picture upper right)
I heard somewhere the technique you're mentioning.
But I'm not quite sure to know all the details needed to use it proficiently
Could you please suggest me some sources where I can learn more on this?...Last edited by handle; 06-07-2020, 11:50 PM.Leave a comment:
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Re: Laptop died - Purism librem15
Hello,
During the day, I overviewed a few pieces of literature on the argument, as you already know I'm not keen on laptop mainboards troubleshooting.
I read on a post that an initial step for fine-tuning a mainboard short circuit, is to measure the resistance between the various coils on the board and the GND.
This should indicate that the power rail where the coil is in is defective (shorted). It seemed reasonable, so I took some measurement and which I summarized on this picture ([url]https://pasteboard.co/JbZMMy7.jpg[/url])....Leave a comment:
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Re: Laptop died - Purism librem15
Hello,
Further investigation I made this evening shown that at least ENE 3930 pins 96, 33 (VCC) have a continuity test ok with GND.
This is suggesting to me that my problem could be a short somewhere in this power rail.
My question is,
Can you suggest a reliable way to find short circuits in such situations?
I do not know where to begin.Leave a comment:
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Re: Laptop died - Purism librem15
Hello,
I did manage to do some tests.
Not completely sure of their results, but I'll try to summarize them in the following:
ISL95520 - the battery charger:[LIST][*] pin 1 (ACIN) - 3v[*] pin 2 (ACOK) - 0v[*] pin 18 (DCIN) -19v[*] pin 31 (CSIN) - 19.2v[*] pin 32 (CSIP) - 19.2v[/LIST]
ENE 3930
I also tested VCC in various places:
[B]pin 96, 33, 9, and it was 0v [/B]
I understand that this might be the problem I was looking for, but if it's so, why do I have 3v on the power button if it is supposed...Leave a comment:
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Re: Laptop died - Purism librem15
Thank you for your precious suggestions. I'll do all the tests as soon as possible.Leave a comment:
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Re: Laptop died - Purism librem15
Hello,
maybe I do not put the necessary enfasis on this point.
The battery charger IC is [B]ISL95520[/B], does this component have any impact on the issue.
I looked for its datasheet, but I just find a sort version which contains just a reference design an a description. It does not even list pin functions. What kind of issues may caused by this component failure?Re: Laptop died - Purism librem15
Hello,
maybe I do not put the necessary enfasis on this point.
The battery charger IC is [B]ISL95520[/B],Leave a comment:
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Re: Laptop died - Purism librem15
I hope not to abuse your patience.
I'm not used to your naming convention, but I guess when you said dc-in MOSFETs, you were referring to the first twos right after the power brick connector.
To make myself clear, I included this schema I made. ([url]https://pasteboard.co/Jbf9fxF.png[/url])
Tensions at gates seem me to be fine; I read 24.4v at MOSFETs gates.
The battery charger IC is ISL95520, and it seems OK too. Voltage readings are coherent with my understanding, and the package condition does not have any evident...Leave a comment:
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Clevo U953 or Purism Librem 15v3
Hello,
I have a problem with the [B]Purism Librem 15v3[/B], which has a mainboard derivated by the [B]Clevo U953[/B].
I'd appreciate if someone would like to share the schematics of any of these twos.Hello,
I have a problem with the [B]Purism Librem 15v3[/B], which has a mainboard derivated by the [B]Clevo U953[/B].
I'd appreciate if someone would like to share the schematics of any of these twos.Hello,
I have a problem with the [B]Purism Librem 15v3[/B], which has a mainboard derivated by the [B]Clevo U953[/B].
I'd appreciate if someone would like -
Re: Laptop died
Hello,
Thank you both for having answered my help request.
By no means I intend to contradict your answer. My question is just because I want to understand the logic behind that.
Several MOSFETs compose the input 19v power rail, I tested the voltage at each source to be at 19v, and at the drain to be 19v. I did not test the gates, because I assumed that if MOSFET is conducting, the relative gate should be high. Where my assumption is failing?
I will check the gate of each MOSFET, to make sure that gate up corresponds to MOSFET...Leave a comment:
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Re: Laptop died
Hello
Thank you for answering me.
Now is a bit late in my time zone, and I place the board to the chassis with all the screws to avoid losing them. Tomorrow I will take it apart again and test the button. I didn't try to push the button and then check the voltage on it again, but I'm sure the voltage was 2.99V, both using power from the charger than using the battery. At a certain moment, I also removed the RTC battery to see if the 3v came from there. As a side note, the RTC battery is critical low, and I read just 0.43v.
Anyway, shouldn't I...Leave a comment:
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Laptop died - Purism librem15
Hello,
I trying troubleshooting my laptop, a purism librem15, which suddenly yesterday morning died, it doesn't charge the battery, and the power led is not lit.
I never tried to repair a laptop, but looking at the PCB, I was persuaded that the problem was just a burned out fuse. ([url]https://pasteboard.co/JaVHnFq.jpg[/url])
I started my troubleshooting convinced that that fuse could be the problem, but then I realized that despite a black mark it had on its surface, it was conducting.
Then I tried to verify a few things I learned reading here and there.
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Re: Troubleshoot l4973d3.3 based power supply subsystem
Hello,
I managed replace both components: the switching regulator and the Zener diode, just to be sure one of those two was faulty.
I struggled one night fighting with the soldering flux residue which appeared to be conductive.
It is the second time in my experience that soldering flux residue makes my work look faulty.
Do you have a special technique to remove residues after your work?
I used alcohol, but after that I had to use hair drier to dry all the board.
However my dect base...Leave a comment:
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Re: Troubleshoot l4973d3.3 based power supply subsystem
Thank you again fo your answer.
Yes I meant the "K" mark on top of the capacitors.
If you look at the picture I shared with you, you may see that not all the capacitors have a "K" mark on their top, infact, just a couple has marks, others do not have any, not a "K", not any other. My guess were that at the beginning no capacitor had, or to say it better they all have cuts on their top, but they were not observable until they inflate because a malfunction.
I were probably wrong,...Leave a comment:
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Re: Troubleshoot l4973d3.3 based power supply subsystem
Thank you for the feedback.
I really appreciated that.
I need some time to recover the hardware needed, the diodes of that kind are not that common.
In the mean time, I'd like to read your opinion on the capacitor issue I mentioned in my previous posts. Is it normal for capacitors in good conditions, to have signs on their top?
The idea that also capacitors can be faulty is bugging me and I'm bugging you. :$Leave a comment:
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Re: Troubleshoot l4973d3.3 based power supply subsystem
According to what I read on this page([URL="https://sciencing.com/test-schottky-diode-6920100.html"]https://sciencing.com/test-schottky-diode-6920100.html[/URL]), and what I comprehend from it, my schottky diode is faulty.
[I]"Reverse the test leads of the multimeter by placing the positive test lead to the cathode and the common test lead to the anode of the diode. Observe whether the multimeter emits a tone. If the multimeter does not sound a tone, the Schottky diode is functioning correctly."...Leave a comment:
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Re: Troubleshoot l4973d3.3 based power supply subsystem
Hello R_J,
Thank you for your precious advice.
I'm anything but skilled in electronic circuits troubleshooting, so I really appreciated the advice to measure resistance between Vout and ground, very clever.
It is about [B]5k ohm[/B], I would say not other shorts are out there, but what if a broken component [B]opens[/B] the circuit rather than short it?
Here a picture of the board, only the upper side. I do not have pictures of the bottom, however bottom has not components, not even a resistor. If...Last edited by handle; 04-07-2019, 03:31 PM.Leave a comment:
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Re: Troubleshoot l4973d3.3 based power supply subsystem
Hello,
I think I managed to answer at least one of the question I posed in previous post, maybe the easier to answer, the name of the diode I suspect to be bad. In my question I used PJ85 as top mark code. It is written indeed on the package, but it is not its top mark. There is also another code which is SK56, that is its top Mark.
Evidences I found seems to converge on "PANJIT semiconductor" SURFACE MOUNT SCHOTTKY BARRIER RECTIFIER VOLTAGE 60V 5.0A.
The easier is answered but all the rest is...Leave a comment:
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Troubleshoot l4973d3.3 based power supply subsystem
Hello,
I'm new on this board, in fact, this is my first thread. Hoping to not be too rude, I'm going to explain why I'm here asking you for help.
I own a Polycom Dect system which suddenly stopped working, my wish, is to be able to fix it up.
This system takes its power from a PoE subsystem which seams to work properly.
The Ethernet switch which suppliws the power, reports it have negotiated the PD with it, which among other things, it means that remote PoE device is working.
Still she system does not start, and a switching regulator which is on the board, becomes... -
Re: New Members - please post your introductions here
Hello, I'm Alessandro from Rome. I always wanted to be able to repair my stuff when they get broken. Now I have one of those situation. I hope some of you may help me in that. Surely I will try help others as much as my limited knowledge permits.Leave a comment:
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