Hi
I am hoping for some help with my D14
DAH98AMBA D0 Rew.D HF model H98A
i doesn’t turn on or charge
i have tried to charge the battery manually, by input 15V at battery), but it still didn’t switch on.
when I connect power (USB-C) to the bare MB
a 2.5V LDO get very hot (70 C) “see picture, where I point”.
LDO pin voltage
1. 0.7V
2. 5.0V
3. 0.6V
4. 0.66V
5. 0.67V
Chg. IC BQ2571 is app. 35 C.
I can’t find any shorts.
I have the schematic from this forum, but it is difficult to read without...
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Re: Dell Latitude E7440 FAN issue
OK, now I have the Mainboar out again, it flickered and shut down once.
I have attached an Arduino Nano, and measure every second at:
+5V_ALW
+3.3V_ALW
+VCC_CORE
And now I cant get it to shut down, I have twisted it 15 min, and let it run an hour..... Just working.
I haven't attached HD, only FAN, RAM and LCD.
So my quistion is:
1. does it need more than
+5V_ALW
+3.3V_ALW
+5V_RUN
+3.3V_RUN
+1.35V_MEM
+0.675V_DDR_VTT
+VCC_CORE
2....
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Re: Dell Latitude E7440 FAN issue
Hi reformatt
Thanks.
It is NOT a termal issue. I was tricked with the FAN didnt start at boot.
If i twist the laptop i can sometime get the screen flicker, and sometime just cut off, even if i run it in BIOS test ePSA (hold Fn and PRW ON) So I would rule out HD etc.
When I had it Dissasambled, I couldt get it to cut off.
Any hints on what prw Rail I should track first?
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Re: Dell Latitude E7440 FAN issue
Hi Adenitz
What I ment was , the laptop Power-off peridically by it self.
And it still does. Sometime I can use it for a day without problems, then suddenty it is dead, but I can start it again right a way. It is very strange.
I have talked with Dell support, but they just told me to buy a new mainboard.
I am lost, I dont know any tools than can get me closer to the issue, I dont get anything from the Windows log other than "it shut down unexpectedly".
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Re: Dell Latitude E7440 FAN issue
update: It is not a FAN issue.
The FAN dosn't start at power-on, only when it gets hot.
The problem was intermittent power off.
I have completely disassambled the laptop, and run severalt test, but i coudn't get it to turn off, I suspect the LCD connector, as the diaplay flickered sometime.
Hopefully it will work now, it is currently testing.....
If you hold Fn at pwr up, it goes into testmode in bios (ePSA)
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Re: Dell Latitude E7440 FAN issue
hi Adenitz
Thanks for quick reply
I It is a brand new FAN, and I have also testede it.
I have cut PWM signal, then the FAN runs at full speed.
In case it was the pull up resistor, I have supplied 3.3V throug a 10K resistor to PWM Pin, and it is still LOW, so it IS SIO that pulls it down.
The funny this is, that sometimes the FAN run when I power down.
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Re: Dell Latitude E7440 FAN issue
Hi Adenitz
Thanks for you reply.
These signals are not DC, when the FAN spins theres pulses on both, when it dosn't work
PWM is stady LOW
TACH is stady high
They are comming directly from SIO, but is there another reasons for not starting the FAN?
I think normally the FAN always run at power up, but on this laptop it dosn't
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Re: Dell Latitude E7440
Thanks, but I didn't find the issue. Made a new post in "Troubleshooting Laptops, Tablets, and Mobile Devices"
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Dell Latitude E7440 FAN issue
Hi
My own laptop Dell Latitude E7440 have a FAN issue, but i can't figure out what it is, so I am hopeing for a little assistance. I have only repaired one PC so far.....
Suddently the PC shut down, it was due to overheating, as the FAN didnt' run.
What i have tried
1. replaced the FAN, no change.
2. Removed the back-up, reset BIOS, no change
3. Measured the 5V for FAN, always there.
Sporadically the FAN runs when I force power down, so I suspect some kind of SW issue. but I have no idear where to look.
Any help a...
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Dell Latitude E7440 LA-9591P
Hi
I need a PCB schmatic for LA-9591P, I allready found the schmatic on google, but it dosn't contain the PCB layout.
PS. the problem is the FAN not running, after 30 reboot it maybe run once.
The PC boots up and run, but overheat and shut down.
Fan swap has been tried without luck.
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Re: motherboard NM-A751 (Lenovo ideaPad 310)
OK, that wasn't fun as a first time laptop repair.
Thanks for all the help anyway.
BR Jesper
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Re: motherboard NM-A751 (Lenovo ideaPad 310)
Hi
That helped
Any tips to proceed ?
Should i choose +3VALQW in nets selection, and just disconnect one after one?
From the schmatic it dosnt seem possible to diconnect the CPU?
/J
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Re: motherboard NM-A751 (Lenovo ideaPad 310)
Hi
Thank you for the quick reply
Unfortenately, i can't open it with the viewers i found
/J
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motherboard NM-A751 (Lenovo ideaPad 310)
Hi
I Am new to Laptop repair, but not to elecronics
Model ?? motherboard NM-A751
Look like the schmatic from here works
[url]https://www.badcaps.net/forum/attachment.php?attachmentid=212317&d=1589197578[/url]
I found the laptop as scrap, but complete without HD
The bare motherboard is stripped, and sometimes draw 100 mA,
then 3VLP and 5VALW is OK
Theres no +3VALW and PU401 get really hot, no change if i press ON/OFF
if i desolder PJ402 it comes up.
After soldering PJ402 again,
I have tried to desolder PJ502,...
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Re: New Members - please post your introductions here
Hi There
I am reparing my first laptop, and allready found a shematic here, great forum. i'am educated in radio/tv 25 years ago, nor i mostly mess with arduino etc.
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