Re: HP Elitebook 840 G3 keeps rebooting
On Diode test to ground. The coils in red read under 10 OHMS.
As for voltages, I'm getting different voltages depending on what side of the coil I measure.
One time I plugged it in and it didn't start resetting and all the voltages on the board were good. Thought I had it. Next time I plugged it in. Back to the same old reset procedure....
Rockton
Member
Last Activity: 09-16-2021, 12:17 PM
Joined: 12-24-2020
Location: Toronto ontario
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Re: HP Elitebook 840 G3 keeps rebooting
An Update
Correction on the voltage drop.
The voltage drops to zero volts every three seconds and the computer resets.
Its stuck in this loop as soon as you plug in the power supply.Leave a comment:
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HP Elitebook 840 G3 keeps rebooting
I have an HP 840 G3 that will not turn on.
It seems to be stuck in an early boot cycle.
As soon as power cord is plugged in, it starts what seems like a 2 second cycle before it resets and starts it again.
If I hold the power button for 12 seconds. The computer orange light stays on but it become non responsive to the power button and some power rails shut off.
When the resets, some voltages briefly drop.
5.v drops to something like 4.8
3.3 drops to 3.1
12v drops to 11.8. Etc.
I have tried reflashing Bios via USB... -
Cannot identify Diode
There is a bad diode in a satellite tuner but I cannot identify what it is to try and replace it. Does anybody know what it is or what diode would work in its place?
It's the D400 spot on the MB and the diode is 2dicg... -
Re: hp 640 g2 need bios dump
I have tried a different memory stick and charger from a different HP. No difference. Same symptoms. Different BIOS versions cause different light configurations on the Keyboard and mail board lights.
Some make Caps light flash, some has charger lights flash, some leave power and other buttons lit. Etc. Never once is there a screen output....Leave a comment:
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Re: hp 640 g2 need bios dump
No luck with the above two.. will keep trying THxLeave a comment:
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Re: hp 640 g2 need bios dump
Is the BIOS original.. No.. The BIOS has been replaced at one time before. After the BIOS was changed the laptop ran for a couple of months. The BIOS chip was purchased programmed online. Popped it in and it worked.
The BIOS I posted in 31 is what I read of the chip in the laptop.
The 640OK Bios is attached here....Last edited by SMDFlea; 04-10-2023, 12:15 PM.Leave a comment:
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Re: hp 640 g2 need bios dump
After finding a Flash in the forum called 640OK I loaded the chip, now the laptop has different symptoms.. Cap Locks key flashes 5 times.. keyboard lights up for about 10 seconds, CPU fan Hums.. but nothing on the monitor.Leave a comment:
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Re: HP Probook 640 G2 dead
I modded the CH341 programmer to 3.3 vdc instead of 5 vdc and use NeoProgrammer 2.1.0.19Leave a comment:
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Re: hp 640 g2 need bios dump
No luck with above flash. Hit power button, keyboard lights up as do WiFi and Spk buttons.. Orange charge light flashes 3 times then stays solid.Leave a comment:
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Re: hp 640 g2 need bios dump
My HP 640 G2 was dead.. Suspect Bios corrupt...
I dumped the BIOS. looking for a clean version to load back on.Last edited by SMDFlea; 04-10-2023, 12:15 PM.Leave a comment:
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Re: HP Probook 640 G2 dead
Ok, i can read and write to the chip now.. I wrote a new bios flash. Computer acts differently now. different lights light up, keyboard lights up.. Screen wont come on so I think its the wrong flashLeave a comment:
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Re: HP Probook 640 G2 dead
OK.. I modded the CH341 for 3.3vdc
I got some sort of a read from the chip.. but when i try to erase it it says it locked or protected.. to hit the unprotect. which does nothing.
I am attaching the chip dump
[url]https://www.badcaps.net/forum/showpost.php?p=1032573&postcount=31[/url]Re: HP Probook 640 G2 dead<br /> <b...protect. whichLast edited by SMDFlea; 03-18-2021, 05:16 PM.Leave a comment:
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Re: HP Probook 640 G2 dead
Yes to all *
Jumper on Pin 1 and 2
Laptop only has orange charge light
t flash three times then stays solid.
The new chips should be in any day now, i will see if it reads them to figure what I will do next...
Just as an FYI.. PIN 1 on the Bios chip on MB has 3.3vdc going to it....Leave a comment:
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Re: HP Probook 640 G2 dead
Good questions.. i will have to check tonight when i get homeLeave a comment:
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Re: HP Probook 640 G2 dead
Both of these tell me chip is not connected or not responding.. so...
I have ordered some new chips, and a new ch341 programmer, ( Cause you never know and they are cheap and it might be faulty or have a bad cable connection etc.) Thanks for the help....Leave a comment:
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Re: HP Probook 640 G2 dead
Tried reading the chip with 341 programmer and 1.8 volts today.
Got all FF FF. So. Not sure if chip is bad, if there's some sort of encryption, or if there is something wrong with my setup. Chip is on the board, no battery or charger hooked up. Looks like I'm going to be up most of the night........Leave a comment:
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Re: HP BIOS unlock tool
For the BIOS dump. Im having some issues. No matter how I try to read it with the 341 programmer with software Asprogrammer with both ver 1.4 and 2.0. Every read of the chip brings up all FF FF ..
I am not sure if the chip is encypted to show this or if the chip is bad.. or if the issue is with the connection. the chip is on the circuitboard, battery is out of laptop, and its not plugged into the charger.Leave a comment:
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Re: HP Probook 640 G2 dead
Ok. I figure the 1vdc goes to the CPU.
So, I think my power to the MB should be ok as I got all the voltages.
Therefore.. my problem might be in the startup chip or bios area?Leave a comment:
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Re: HP Probook 640 G2 dead
Pin 4 is the gate voltage so I assume it’s going to some power control chip. . I am guessing that this mosfet is there just in case you plug in a power supply that’s not Center positive.
I am curious about the 1 volt Pads.Last edited by Rockton; 03-12-2021, 02:13 PM.Leave a comment:
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