Troubleshooting • Re: Raspberry Pi 4B red indicator light from on to gradually off

Your board looks like a version before the PMIC was changed to a different one. The earliest schematic I can find is at https://web.archive.org/web/20211017004 ... matics.pdf. Your capacitor appears to be the one after the inductor on pin 30 of the PMIC. If so it is C8, 47uF 6.3V.

Thanks for the schematic you provided. I've been waiting for the new PMIC and capacitors for a few days now. In the meantime, my Raspberry Pi 4B won't power up again (I removed C8). It was working fine the day before, but the next day, the red light just flashed and went out as soon as I powered it on (it used to last for about 3 minutes).
After I took out the PMIC, I found that the DDR section has a very low resistance to ground, around 6 ohms. I tested this with the capacitor pins connected to the ground. I think that's not normal, and that's why the multimeter kept beeping continuously when I measured the C8 capacitor last time. I want to know if this resistance value is normal.I took another close look at the schematic. When the red light goes out, the 5V on my board is normal. The schematic shows that it's also affected by the PWR_LED_OFF network. Is this a command from the main controller that triggers at that time?

Statistics: Posted by HarryWang — Sat Jun 15, 2024 7:11 am

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