raspberry pi 3 model b c163 capacitor replacement

[Burzullah]

So basically I accidentally removed the c163 capacitor and just soldered a 47uf 805 capacitor to its place. I am using the Raspbian OS but when I plug the Raspberry it starts booting but shows an error like [end Kernel panic - not syncing: Fatal exception in interrupt ]. Please help.

[pidd]

It shouldn't be too critical changing a tantalum to ceramic. I'd get your magnifying glass out and check you haven't got any solder tails.

[mahjongg]

I looked in the partial schematics of the RPI3B+ but it doesn't have a C163, so how do you know its value?
and where is it, what function does it have.

If you replaced it with an equivalent, and it didn't help I'm must assume there is more damage done than only the removal of a cap..

[pidd]

C163 is near sw1 and sw2 of the RT8088AWSC, top right corner

[Imperf3kt]

I've had that error message once before. It was after my Pi was shut down abruptly thanks to a power failure.
The SD card had been corrupted and I had to reflash it.

[mahjongg]

C163 is near sw1 and sw2 of the RT8088AWSC, top right corner

Which schematic are you using? mine (https://www.raspberrypi.org/documentati ... educed.pdf)
doesn't even have an RT8088AWSC switcher, it uses a XR77004 switcher instead.

In my top right hand corner the ethernet PHY is shown, no sw1 or sw2 in sight (a RPI3B+ doesn't even have "switches" (SW1 or SW2)).

we are obviously not talking about the same schematic, or perhaps even the same RPI, sounds more like your compute module carrier board.

[trejan]

C163 is near sw1 and sw2 of the RT8088AWSC, top right corner

Which schematic are you using? mine (https://www.raspberrypi.org/documentati ... educed.pdf)

OP said they have a 3B not 3B+. C163 is connected to the output of the RT8088AWSC in the top right corner of the 3B schematic.

[hippy]

I looked in the partial schematics of the RPI3B+ but it doesn't have a C163

I would guess because the OP has a Pi 3B not a 3B+

Though "Pi 3B" is absolutely correct a lot of people do seem to presume "3B+" when "3B" is written. That's the reason I usually explicitly write "Pi 3B (non-plus)" to avoid any confusion or misinterpretation.

Cross-posted with trejan

[mahjongg]

Ah, yes that explains it. I could have sworn he talked about the 3B+ before, I remember checking.

But okay, C163 is the "bulk capacitor" for the CPU voltage, (V_core) after the switchers inductor, normally that is a low impedance capacitor, but if a good cap is present it should work, and depending ion how its programmed (Via 12C) it will hold the core voltage of the SoC, which is variable, but should be something like a few volt.

the original cap is larger than an 0805.

[hippy]

C163 is the "bulk capacitor" for the CPU voltage, (V_core) after the switchers inductor, normally that is a low impedance capacitor, but if a good cap is present it should work

I would expect it to work, and it seems to initially as it does boot.

That the kernel then panics I would suspect to be more of a problem with a corrupted card ( as Imperf3kt suggests ) than the cap not holding up.

If a new or reflashed card works I would consider that to be the case though it would be worth running through a cycle of stress tests and idling just to confirm the cap is holding up.

[mahjongg]

agreed.

[pidd]

Thinking about this again, there was a discussion recently saying that these small ceramics have a poor current capability and I guess that may have been why the original was a tantulum.

Its all after my time, the idea of 47uF being this small in the first place is a bit of a mind-blower, then to age me further, there's such a thing as a tantulum chip capacitor. I really need to get up to date but too much to do and too little time to do it in. Electronics was my base trade.

[mahjongg]

The main reason that a 47uF cap (ceramic or tantalium oxide) can be this small is that it only has a very small maximum voltage rating (very thin dielectricum) for example 6.3Volt. and yes, tantalium capacitors can be chip sized.