Hi everyone, I want to understand the basic electronic circuit of an old motherboard. I need some guidance about ins and outs of this circuit, e.g. what feeds power into the CR2032 battery and how does it work.
Best regards.
Best regards.
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Re: I need a basic BIOS circuit
Is it a common BIOS chip like the attached picture? Are you trying to work out how the CR2032 powers the chip?Attached Files -
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Re: I need a basic BIOS circuit
Not sure exactly what you are asking for. The schematic of how the battery is connected?
https://www.makeuseof.com/tag/why-do...ave-a-battery/
https://www.deskdecode.com/cmos-battery/Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: I need a basic BIOS circuit
the battery has nothing to do with the bios, it just runs the real-time clock.Comment
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Re: I need a basic BIOS circuit
The battery used to have to do with the BIOS settings. Nowadays indeed it does nothing much except run the clock. The BIOS settings are stored in the ROM itself. As a side note, that's why BIOS goes bad so often on modern boards.
Now coming back to the question asked, there is a double diode which feeds the CMOS memory. One side comes from the RTC battery, the other from a 3.3V source which is always present as long as the device is plugged in.A working TV? How boring!Originally posted by PeteS in CAComment
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Re: I need a basic BIOS circuit
What make and model of motherboard?Follow me on YouTube
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Learn Electronics Repair
https://www.youtube.com/channel/UCFX...R8UZ2vg/videosComment
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Find by serial number,model number or series
If you know the laptop serial or model number go to HP support https://support.hp.com/us-en/drivers/laptops .
Enter the serial number or model number and click submit.On the next screen you will have to enter the OS
Operating system and OS version.If... -
Hi, my laptop wont boot at all
With original bios no POST, only LED lights
With alternative BIOS from model TP500LN (flashed via programmer) the notebook works again
Some issues
A- with bios from 500LN, it won't update from bios of model 500LA (from 500LN v203 to 500LA v300)
B- If updated from 500LN version 203 to 300, the battery stops being recognized
Things I tried
1- Update / clear ME: Took the non working bios, made a backup, and did this: https://www.badcaps.net/forum/troubl...theory/trouble... -
Hello, I have an old Dell G3 3579 (ST: 2WQ7LP2-8FC8) with a newer 8FC8 BIOS password. I have successfully attached to the flash chip (W25Q128JVSQ) on the motherboard with a CH341A programmer and made several modifications using Intel FIT (e.g., allow software SPI write) without bricking. I was also able to boot to a modified GRUB shell where I attempted to edit many BIOS security related options like BIOS Guard/Lock, Flash Signature Override, ME FW Image Re-Flash, etc.
Unfortunately, some of these modifications like to Intel BIOS Guard failed because it is fused into the PCH. Also,... -
Hello,
I have a Lenovo Thinkbook 15 G2 ITL i5 Laptop (serial number: MP2BFZEF) that when I turn it on, the led on the power button lights up for 5 seconds, then goes out. There's no display and nothing happens.
So I thought it was a Bios problem.
I found 3 bios chips on the board, which I read with a bios programmer: two XMC model bios chips and a Winbond model bios chip. Each XMC model bios chip has two partitions named XM25QH128A [3.3V] and XT25F128A [3.3V]. And the Winbond model bios chip has three partitions named W25Q80BL 3.3V, W25Q80xV 3.3V and W25Q80DV 3.3V.... -
Summary of BIOS Whitelist Removal Problem
Problem:
I am attempting to remove the WWAN card whitelist from my Lenovo ThinkPad T560.
Initial Findings:- My current BIOS version is N1KET58W (1.45).
- I have a CH341A programmer and have successfully created two full backups of my BIOS.
- I have the ability to use command-line tools on a Linux machine.
- I attempted to use several automated and manual patching methods on my N1KET58W (1.45) BIOS, including using hex strings. These attempts all failed.
- I concluded that the
08-12-2025, 03:01 PM
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