SomeOneOnTheNet
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Small part fell off my pi

Sat May 11, 2019 4:03 pm

A small part called "C50" fell off my pi and now im not sure if im not loading the os right or if the raspberry pi really needs the part as i have read that some small parts that are not on the pi continue working

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mahjongg
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Re: Small part fell off my pi

Sat May 11, 2019 9:50 pm

you don't even mention which PI you are talking about, partial schematics of all PI's are here, https://www.raspberrypi.org/documentati ... /README.md

but C50 is not on the schematic of the PI3B+.

the proof of the pudding is in the eating, does your PI still boot?

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ptimlin
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Re: Small part fell off my pi

Sun May 12, 2019 4:40 am

Most likely it is a small filter capacitor and your Pi will work fine without it.

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Burngate
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Re: Small part fell off my pi

Sun May 12, 2019 8:54 am

Post a picture - there are several examples around - with the part ringed, so someone could identify it.

SomeOneOnTheNet
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Re: Small part fell off my pi

Sun May 19, 2019 11:40 pm

this is the piece that fell off the pi

(its the raspberry pi 3 b+ btw)
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Re: Small part fell off my pi

Mon May 20, 2019 1:10 am

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dl324
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Re: Small part fell off my pi

Mon May 20, 2019 2:37 am

If it was my Pi, I'd replace the capacitor. Designers usually over design filtering, but there's no point in tempting fate. It being gone could cause random failures due to supply glitches.

ankith26
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Re: Small part fell off my pi

Mon May 20, 2019 10:18 am

I fail to see how this will cause problems on boot. This looks like its related to audio jack when i examined my pi.
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Re: Small part fell off my pi

Mon May 20, 2019 10:40 am

From your photo you gave,I can take it as a C58 , but from a raspberry pi 3b.
Saw the schematics of the 3b and it is there. looks like a vital capacitor for the audio jack
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Imperf3kt
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Re: Small part fell off my pi

Mon May 20, 2019 7:29 pm

Yes, it carries the left audio signal to the A/V jack. See my link just a couple of posts ago.

You could either replace the capacitor or just short the connection with some wire.without it, the Pi will still function 100% normal (except you'll get no L channel audio over the A/V jack.)
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davidcoton
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Re: Small part fell off my pi

Mon May 20, 2019 9:30 pm

Imperf3kt wrote:
Mon May 20, 2019 7:29 pm
Yes, it carries the left audio signal to the A/V jack. See my link just a couple of posts ago.

You could either replace the capacitor or just short the connection with some wire.without it, the Pi will still function 100% normal (except you'll get no L channel audio over the A/V jack.)
Do NOT short the connection. C58 is a DC blocking capacitor and is necessary to prevent possible damage to the Pi, and even in the absence of damage it may be necessary for an undistorted signal. Either leave it open (no L channel audio) or replace the cap.
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Imperf3kt
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Re: Small part fell off my pi

Mon May 20, 2019 11:26 pm

davidcoton wrote:
Mon May 20, 2019 9:30 pm
Imperf3kt wrote:
Mon May 20, 2019 7:29 pm
Yes, it carries the left audio signal to the A/V jack. See my link just a couple of posts ago.

You could either replace the capacitor or just short the connection with some wire.without it, the Pi will still function 100% normal (except you'll get no L channel audio over the A/V jack.)
Do NOT short the connection. C58 is a DC blocking capacitor and is necessary to prevent possible damage to the Pi, and even in the absence of damage it may be necessary for an undistorted signal. Either leave it open (no L channel audio) or replace the cap.
I thought it was just a high pass filter, but upon looking it up, it seems a high pass filter doubles as a DC blocking circuit.
Thanks for pointing that out. I'll remember it in future.
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Re: Small part fell off my pi

Tue May 21, 2019 4:18 am

I would want to know if such a thing happened to me..From where will we get these tiny capacitors. Does the RPF issue spare parts or something
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Imperf3kt
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Re: Small part fell off my pi

Tue May 21, 2019 4:36 am

Any capacitor rated 47uf and 2v or higher will work. Just be aware of polarised capacitors, such as electrolytic, as they must be put the correct way around.

The Raspberry Pi foundation does not sell spare parts, but you can get the required bits anywhere. Ebay or Amazon should sell some in packs of ten or so for a reasonable price. Or you may be lucky enough to have a local supply chain nearby, as I do.
There is also the third option which I would actually recommend and that is to scavenge a capacitor from a dead electronic device. 47uf is extremely common.

You will require soldering skills or someone who can solder for you.
Also note that if your Pi is still under warranty, any attempt at self repair will invalidate the remaining warranty.
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Burngate
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Re: Small part fell off my pi

Tue May 21, 2019 9:56 am

davidcoton wrote:
Mon May 20, 2019 9:30 pm
Do NOT short the connection. C58 is a DC blocking capacitor and is necessary to prevent possible damage to the Pi, and even in the absence of damage it may be necessary for an undistorted signal.
I'm not convinced on either point.

The jack can short the left audio to ground as the plug it's being inserted into the socket, so let's assume the worst case, and it's permanently short.
In that case, you've still got 220R in series, so a maximum of 15mA and average 7.5mA - not going to hurt anything (U11 might get warm)

Without that short, and feeding into a high impedance (as it's designed for) there'll be the same undistorted audio signal, just with 1v offset.
The load might not like that, but if it's designed properly it should have its own blocking capacitor, so it won't make any difference.

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Re: Small part fell off my pi

Tue May 21, 2019 4:31 pm

Burngate wrote:
Tue May 21, 2019 9:56 am
davidcoton wrote:
Mon May 20, 2019 9:30 pm
Do NOT short the connection. C58 is a DC blocking capacitor and is necessary to prevent possible damage to the Pi, and even in the absence of damage it may be necessary for an undistorted signal.
I'm not convinced on either point.

The jack can short the left audio to ground as the plug it's being inserted into the socket, so let's assume the worst case, and it's permanently short.
In that case, you've still got 220R in series, so a maximum of 15mA and average 7.5mA - not going to hurt anything (U11 might get warm)

Without that short, and feeding into a high impedance (as it's designed for) there'll be the same undistorted audio signal, just with 1v offset.
The load might not like that, but if it's designed properly it should have its own blocking capacitor, so it won't make any difference.
But what if the output is connected to a device, running on a 12V supply, that biases its input to half rail? 6V straight into the Pi's innards, and no guarantees that the source impedance is high enough to provide protection. Even if it is, the Pi's output will be clipped.
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Burngate
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Re: Small part fell off my pi

Tue May 21, 2019 5:03 pm

Without C83, 6v into the left channel will end up on the output of U11, and probably kill it. As long as it can supply 60mA at that voltage through R17.
But with C83 in the way, that cap will be reverse-biased and will act like a short circuit, so the end result will be the same.

TL;DR If the op doesn't want analogue audio, he doesn't need to do anything.
If he does, and his soldering skills are up to replacing the cap, then he should do so.
Otherwise, shorting out with wire will work without much problem.
Last edited by Burngate on Wed May 22, 2019 9:02 am, edited 1 time in total.

Brandon92
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Re: Small part fell off my pi

Tue May 21, 2019 5:21 pm

Burngate wrote:
Tue May 21, 2019 5:03 pm
Without C83, 6v into the left channel will end up on the output of U11, and probably kill it. As long as it can supply 60mA at that voltage through R17.
But with C83 in the way, that cap will be reverse-biased and will act like a short circuit, so the end result will be the same.
Are you sure about the "reverse-biased" of the capacitor. Because those capacitors looks like a "Ceramic capacitors" to me and they don't have a polarity. So, they will block indeed a DC.

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Burngate
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Re: Small part fell off my pi

Wed May 22, 2019 9:23 am

No, actually, I'm not sure.
At least in the old days 47μF was far too big for ceramic, but now it seems 47μF in case size 3216 is available as multilayer ceramic as well as tantalum, etc.

My point still stands: whatever you plug into this shouldn't be feeding anything back into the Pi, and won't damage it, with or without a blocking capacitor.

Of course, it's always possible to find a way to damage things; if you don't have a faulty amp to plug into it, you could always put mains into it. Or just use a hammer.
But realism is advantageous.

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Re: Small part fell off my pi

Wed May 22, 2019 10:33 am

Burngate wrote:
Wed May 22, 2019 9:23 am
No, actually, I'm not sure.
At least in the old days 47μF was far too big for ceramic, but now it seems 47μF in case size 3216 is available as multilayer ceramic as well as tantalum, etc.

My point still stands: whatever you plug into this shouldn't be feeding anything back into the Pi, and won't damage it, with or without a blocking capacitor.
Yup, the new parts are great :D

And if the amplifier is good, its should indeed not matter. Because if have its own input capacitor, like you said before.
However I'm not so sure if this is good for a headphone itself if you don't use that capacitor. But for the Rpi it doesn't matter.

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Re: Small part fell off my pi

Wed May 22, 2019 5:07 pm

Brandon92 wrote:
Wed May 22, 2019 10:33 am
However I'm not so sure if this is good for a headphone itself if you don't use that capacitor.
Yet one more thing I don't know. The list just keeps growing.
And I don't intend experimenting with this, 'cos I like my sound through big speakers!

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