I replace the resistor with one I found on scrap board, 20K, but with that one the probleme remain the same :'( 0.5V on JRST2402 et board doesn't work.
What is wrong with that board? :/
I replace the resistor with one I found on scrap board, 20K, but with that one the probleme remain the same :'( 0.5V on JRST2402 et board doesn't work.
What is wrong with that board? :/
remove the cap with +0.5V next to resister and see if the voltage 3.3V is stable
Ok thanks, I'll check if I find one.
Last question, sorry i'm annoying I know
Can you explain what's the job of RTC_RST# function and why it prevent others power supply to start?
Thank you for you advise, unfortunatly I didn't find a cap and gave back the laptop to my familly. I think they let me know fast if it fail to start properly.
Is it dangerous or just unstable?
Can you explain the function of RTCRST? (just for me being less noob)
RTCRST# resets the Real Time Clock inside the PCH when it's pulled low. It also has the side effect of triggering a "clear CMOS", ie. resetting BIOS settings to the default.
The PCH cannot work if its Real Time Clock is not working so RTCRST# always has to be high.
The resistor and the capacitor act as time delay and stabilisation for this signal when the machine first receive power (after AC adapter, main battery and coin cell battery were all removed). Without the capacitor, the reset signal can come up "too soon" and the PCH may try to initialize the Real Time Clock while the RTC power rail isn't stable yet, causing it to crash.
Hello, I have the same board, with exactly the same problem. I measured the voltages and have the same results as alderick. I reprogrammed the bios, but the problem remains.
Do you have more info about the cap and resistor you jumped ?
I can find JRST2402 near the ram-slot, but I cannot seem to find this cap and resistor.
I can also not find a schematic or boardview to help
Hello,
I don't remember which side of the board that cap is but you can find it with multi meter in beep mode, one probe on JRST2402 (RTC_RST side not GND obviously) et try all caps around the SOC.
Reprogram bios is useless in that case, the only faulty thing was the cap, just find it and replace it.
Thanks a lot guys, thanks to this topic I did manage to solve the problem. I found the cap and replaced it with one from a scrap board.
In case someone else runs in to this problem, attached is an image of the cap that needed replacement.
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