steinerlein
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What value are those parts?

Tue Aug 07, 2018 3:40 pm

Hello all,

today, in an unexpected and completely unnecessary move, I used compressed air to blow off excess solder from soldering the GPIO pin header. In doing so I also blew off two passives on the board, without realizing it at first. They are long gone and I need to know their values to be able to replace them. Please see the attached picture.
pi.JPG
pi.JPG (254.06 KiB) Viewed 1720 times
I am now educated about the stupidity that was involved and am asking your help with this. I hope that someone can tell me what to put there.
Thanks, all the best!

jamesh
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Re: What value are those parts?

Tue Aug 07, 2018 4:12 pm

The guy who knows is on holiday, but will email him just in case.
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hippy
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Re: What value are those parts?

Tue Aug 07, 2018 7:44 pm

If RPT doesn't already keep full circuit diagrams of each board and layouts with component identifications marked; may I suggest they do or questions like this are going to be almost impossible to answer with the passing of time.

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Re: What value are those parts?

Tue Aug 07, 2018 9:04 pm

Both are

CAP, CERAMIC 0.1uF X7R 1005, 10%, 16V.
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Re: What value are those parts?

Tue Aug 07, 2018 9:07 pm

Don't take this as the answer.
The one in its own is next to pin17 3V3 so it could be the 100nF 1005 style. (C64)


Edit too slow to reply, as above post :-)

steinerlein
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Re: What value are those parts?

Wed Aug 08, 2018 8:20 am

Thank you all very much, you have helped me a lot!

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Re: What value are those parts?

Wed Aug 08, 2018 10:13 am

hippy wrote:
Tue Aug 07, 2018 7:44 pm
If RPT doesn't already keep full circuit diagrams of each board and layouts with component identifications marked; may I suggest they do or questions like this are going to be almost impossible to answer with the passing of time.
... How would we be able to assemble boards if we didn't?
Rockets are loud.
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Re: What value are those parts?

Wed Aug 08, 2018 10:55 am

jdb wrote:
Wed Aug 08, 2018 10:13 am
hippy wrote:
Tue Aug 07, 2018 7:44 pm
If RPT doesn't already keep full circuit diagrams of each board and layouts with component identifications marked; may I suggest they do or questions like this are going to be almost impossible to answer with the passing of time.
... How would we be able to assemble boards if we didn't?
Tru Dat.

For the absolving of any doubt, yes, we do have full circuit diagrams of all of our products! Not sure why anyone would think we don't. Absence of *publicly* available documents doesn't mean it doesn't exist *privately*.
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Re: What value are those parts?

Wed Aug 08, 2018 12:46 pm

jamesh wrote:
Wed Aug 08, 2018 10:55 am
For the absolving of any doubt, yes, we do have full circuit diagrams of all of our products! Not sure why anyone would think we don't. Absence of *publicly* available documents doesn't mean it doesn't exist *privately*.
It was more the layout component identification I was wondering about. It is entirely possible to do schematic capture and then not easily know where components in the schematic are placed on the board.
jdb wrote:
Wed Aug 08, 2018 10:13 am
... How would we be able to assemble boards if we didn't?
To assemble a board one only needs to know component value, placement position and orientation. What the schematic is, how the components relate to that schematic, what its component identifier may be, is irrelevant to assembly.

Some boards may have "C1", "R1" etc identifiers silk-screened on them, others may only have values indicated, "100nF", "27R" etc. Latest Pi boards have neither for most components.

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Re: What value are those parts?

Wed Aug 08, 2018 5:01 pm

hippy wrote:
Wed Aug 08, 2018 12:46 pm
Some boards may have "C1", "R1" etc identifiers silk-screened on them, others may only have values indicated, "100nF", "27R" etc. Latest Pi boards have neither for most components.
Interesting thought. The silk-screen identifiers are irrelevant for assembly
So why do some components have them?

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Re: What value are those parts?

Wed Aug 08, 2018 5:10 pm

Burngate wrote:
Wed Aug 08, 2018 5:01 pm
Interesting thought. The silk-screen identifiers are irrelevant for assembly
So why do some components have them?
Maybe for occasional manual production checks?

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Re: What value are those parts?

Wed Aug 08, 2018 5:25 pm

Burngate wrote:
Wed Aug 08, 2018 5:01 pm
hippy wrote:
Wed Aug 08, 2018 12:46 pm
Some boards may have "C1", "R1" etc identifiers silk-screened on them, others may only have values indicated, "100nF", "27R" etc. Latest Pi boards have neither for most components.
Interesting thought. The silk-screen identifiers are irrelevant for assembly
So why do some components have them?
Do you mean components or did you mean boards ?

For components I would say labelling is mostly to enable humans to more easily verify it's the right part in the bin, the right part being used, or which is which when you've just put two bags of similar looking things on one's desk.

For boards I would say it's to aid human assemblers, and to help identify exactly what has been knocked off a board when that's been done as here. A value indicates what's gone so aids replacement but doesn't help identify the consequences of not replacing it. An identifier lets one know what in the circuit has gone AWOL but replacement is only possible if one knows what value it should have. The consequence of not replacing is also only possible if it is on an available circuit diagram.

If one doesn't have values shown on a board, don't have identifiers or a circuit diagram or list showing what it is, one cannot replace a dislodged component without having help from someone who has access to that 'secret information'. And if that 'secret information' ever gets lost it's a real bugger to find what it should be.

If the board discussed here had the value marked the OP's question would never have needed to be asked.

If it had an identifier and the full circuit diagram were available the OP could have answered the question for themself.

As it is the question has to be asked. And if there is no one who can answer the question that becomes problematic. Not totally impossible to answer, but not so easy.

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Re: What value are those parts?

Thu Aug 09, 2018 7:56 am

Yes, that much is reasonable.
It would have been useful in this instance to aid identification, provided one had the full schematic, though having that available is a bad idea for other reasons (if that weren't true, Eben would have let us have it; since he hasn't, it must be true)

But ...
The Pi isn't hand-assembled, so silk-screen on the board is of no use for assembly.

The silk-screen identifies the board - B+, 2B, 3B, 3B+ - for sales people further down the line - Maplin's etc. - so they don't have to fire it up before selling it.
It also has date of assembly, etc., which can help identify manufacturing problems. If a component (or its source) is changed during the life of a board, and an increased number start being returned as DOA, then that change can be identified and reverted.

"Occasional manual production checking" doesn't really cut the mustard - one doesn't need the component number silk-screened on board to be able to check the outputs of the DC-DC regulator, for example. One should already know what one's going to measure before one starts.

So if there's no good reason for putting some component labels on the board, why do some others have labels?

We could have gone down a different route; we could have sacrificed another board, removed the appropriate components and measuring them; but we didn't.

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Re: What value are those parts?

Thu Aug 09, 2018 10:26 am

Burngate wrote:
Thu Aug 09, 2018 7:56 am
It would have been useful in this instance to aid identification, provided one had the full schematic, though having that available is a bad idea for other reasons (if that weren't true, Eben would have let us have it; since he hasn't, it must be true)
Eben & Co appear to have decided silk-screening identifiers on the board and releasing full circuit diagrams is a bad idea but others would disagree.

We don't know how or why that conclusion was arrived at but I would guess it's some sort of IP protection effort, an attempt to frustrate anyone trying to figure the board out or reverse engineer it.

Almost entirely pointless in my view because, no one can get hold of the Broadcom SoC unless purchasing in huge quantities, full circuit diagrams and silk-screen identifiers are not enough to replicate a Pi board, and anyone determined to do that could do it without having either.

It's an over-zealous approach to IP protection in my opinion but that's what businesses, even charities, raking in £28 million ($36 million) a year tend to drift towards. Protecting the revenue stream becomes the primary and all important business concern. That's simply the way it is.
Last edited by hippy on Thu Aug 09, 2018 10:41 am, edited 1 time in total.

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Re: What value are those parts?

Thu Aug 09, 2018 10:41 am

hippy wrote:
Thu Aug 09, 2018 10:26 am
Burngate wrote:
Thu Aug 09, 2018 7:56 am
It would have been useful in this instance to aid identification, provided one had the full schematic, though having that available is a bad idea for other reasons (if that weren't true, Eben would have let us have it; since he hasn't, it must be true)
Eben & Co appear to have decided silk-screening identifiers on the board and releasing full circuit diagrams is a bad idea but others would disagree.
Not a good idea, but not for the reason you think. There is simply not enough room on the board to silk screen all the components, and a lot of people do not realise how much time it takes, on a board of this complexity, to actually design the silk screen, it's a manual process. Since we cannot do all components, and it takes ages, we simply don't do it!
hippy wrote:
Thu Aug 09, 2018 10:26 am
We don't know how or why that conclusion was arrived at but I would guess it's some sort of IP protection effort, an attempt to frustrate anyone trying to figure the board out or reverse engineer it.
Correct for the schematics. Not for silk screen.
hippy wrote:
Thu Aug 09, 2018 10:26 am
Almost entirely pointless in my view because, no one can get hold of the Broadcom SoC unless purchasing in huge quantities, full circuit diagrams and silk-screen identifiers are not enough to replicate a Pi board, and anyone determined to do that could do it without having either.
Not true. Brcm will sell the SoC's to anyone, it's just a question of quantity and money. Lack of schematics is one way we protect our IP (which is actually worth a lot of money), it's not the only one.
hippy wrote:
Thu Aug 09, 2018 10:26 am
It's an over-zealous approach to IP protection in my opinion but that's what businesses, even charities, raking in $28 million a year tend to drift towards. Protecting the revenue stream becomes the primary and all important business concern. That's simply the way it is.
Your over zealous is our staying in business. That revenue stream is paying for a lot of development, and lot of education. If it goes the next Pi will not appear (well, maybe the one after next)
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Re: What value are those parts?

Thu Aug 09, 2018 10:56 am

jamesh wrote:
Thu Aug 09, 2018 10:41 am
There is simply not enough room on the board to silk screen all the components
Which seems odd when there appears to be fewer components on the boards without identifiers than the earlier boards which had them -

https://www.digikey.com/-/media/MakerIO ... /Fig-3.jpg

The same seems true of the underside.
jamesh wrote:
Thu Aug 09, 2018 10:41 am
and a lot of people do not realise how much time it takes, on a board of this complexity, to actually design the silk screen, it's a manual process. Since we cannot do all components, and it takes ages, we simply don't do it!
I guess it depends on the software used. I don't know what it was the company I worked for used but it seemed to automatically generate a silkscreen which put identifiers where the components were and all the designer had to do was drag them to clear space. That took virtually no time at all.

I would argue it would be worth the time and cost anyway when manufacturing 10 million or so boards, because it likely costs more having to answer "what value is this part?" questions. But it is a decision for RPT to make.

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Re: What value are those parts?

Thu Aug 09, 2018 12:43 pm

One must wonder why silkscreening has declined as new boards are developed.
I have a few Pi, and the older the Pi, the more detailed the silkscreen was. The newest Pi I have (2017 Pi0w) has practically no silkscreen labelling, despite being identical to the 2016 Pi0w in parts, design and revision number. Why remove the silkscreen, you clearly already had it made and would have had to adjust it to take stuff away!
55:55:44:44:4C
52:4C:52:42:41

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Re: What value are those parts?

Thu Aug 09, 2018 1:47 pm

hippy wrote:
Thu Aug 09, 2018 10:56 am
jamesh wrote:
Thu Aug 09, 2018 10:41 am
There is simply not enough room on the board to silk screen all the components
Which seems odd when there appears to be fewer components on the boards without identifiers than the earlier boards which had them -

https://www.digikey.com/-/media/MakerIO ... /Fig-3.jpg

The same seems true of the underside.
jamesh wrote:
Thu Aug 09, 2018 10:41 am
and a lot of people do not realise how much time it takes, on a board of this complexity, to actually design the silk screen, it's a manual process. Since we cannot do all components, and it takes ages, we simply don't do it!
I guess it depends on the software used. I don't know what it was the company I worked for used but it seemed to automatically generate a silkscreen which put identifiers where the components were and all the designer had to do was drag them to clear space. That took virtually no time at all.

I would argue it would be worth the time and cost anyway when manufacturing 10 million or so boards, because it likely costs more having to answer "what value is this part?" questions. But it is a decision for RPT to make.
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Re: What value are those parts?

Thu Aug 09, 2018 1:56 pm

Given the number of people asking is few, and the board looks tidier for it (as it moves into a more mainstream product).
I honestly don't see the problem.

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Re: What value are those parts?

Thu Aug 09, 2018 2:19 pm

bensimmo wrote:
Thu Aug 09, 2018 1:56 pm
I honestly don't see the problem.
If you ever knock a component off an unlabelled board and cannot find out what it was and what value it has to replace it and cannot determine what the consequences might be if you don't you might appreciate why it can be a problem.

Even trying to indicate to others what's gone missing may mean having to post an annotated photo with all the effort that entails rather simply posting the component's identifier as would be the case if they were silk-screened on the board.

That may also be the case if someone has to report some component let loose its magic smoke or appears to be getting unreasonably hot.

When past Pi owners panicked with "I've knocked C6 off the board!", "D1 is smoking!", those with electronics experience all knew, or could discover pretty quickly, what they meant, where that was, what that component was and did, could make a good educated guess as to what the consequences of not replacing it would be, and what the problem may have been if there was one.

On the newer boards, with no silk screen, no full circuit diagrams, only those with insider information may know the answer.

To me that puts Pi users in a worse situation than they were previously in. It leads to "throw it away, buy a new one", limits the options for attempting a repair, or even advising on the issue.

But you are right, it's not a problem for most people.

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Re: What value are those parts?

Thu Aug 09, 2018 3:32 pm

Yes and there has o my been a few people actually ask. Most the time it's still been a best guess with the numbers.

I've knocked the ceramic antenna off the Pi3 and had to add an external setup. Stuff happens and it is in the Chuck and buy price catagiry for most people.

Many things I have do not have schematics even if they have the numbers on them. So they just don't help.

I do have a lot of 80s and 90s equipment made from larger components, as they were, that have the full schematics and part numbers etc. Which is excellent for me maintaining them within schools.

It does however, more often than not, cost more in my time (and bargain basement money equivalent) to read, find and purchase, repair and test the device compared to just buying something new.


Nobody has moaned that the Zero has never had them labelled,
...nor has a micro:bit the two that would probably get knocked around the most.
I don't think Pimoroni parts do either, at least not the ones in front of me.

The best place for that sort of detail is in schematics and 3D models of them or actual layout drawings on a file somewhere.
Two/three things they would already have.

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Re: What value are those parts?

Thu Aug 09, 2018 4:59 pm

bensimmo wrote:
Thu Aug 09, 2018 3:32 pm
I do have a lot of 80s and 90s equipment made from larger components, as they were, that have the full schematics and part numbers etc. Which is excellent for me maintaining them within schools.
I remember the days when one could contact almost any company and they would send a schematic back. I am not sure if there was a Home Computer whose documentation did not have a circuit diagram included.

Those were the days when we had a wealth of electronics magazines and component shops around. It isn't just interest in programming we lost over the years, and I had hoped the Pi would bring back the full Home Computer experience for a new generation, software and hardware.

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Re: What value are those parts?

Thu Aug 09, 2018 7:50 pm

hippy wrote:
Thu Aug 09, 2018 4:59 pm
bensimmo wrote:
Thu Aug 09, 2018 3:32 pm
I do have a lot of 80s and 90s equipment made from larger components, as they were, that have the full schematics and part numbers etc. Which is excellent for me maintaining them within schools.
I remember the days when one could contact almost any company and they would send a schematic back. I am not sure if there was a Home Computer whose documentation did not have a circuit diagram included.

Those were the days when we had a wealth of electronics magazines and component shops around. It isn't just interest in programming we lost over the years, and I had hoped the Pi would bring back the full Home Computer experience for a new generation, software and hardware.
I think the educational mission of the Raspberry Pi is why people have such high standards for documentation and transparency ideals about how it works. While the statement most people aren't affected by loss of the silkscreen is likely true, it is also true that most people aren't affected by the loss of built-in programming tools on Windows PCs and tablet computers. In my opinion, the truth of both these statements comes from a lack of technical and computer literacy--exactly the problem that the Raspberry Pi was originally designed to address.

Does success always lead to loss of ideals and eroding standards? There must be an example, perhaps in Hollywood, where success leads to an increased ability to preserve ideals and improve standards. With that in mind, it would be wonderful if the production version of the next Pi model included a descriptive silkscreen as well as a technical document that could be used by teachers to encourage students to learn more about computer hardware.

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Re: What value are those parts?

Thu Aug 09, 2018 8:55 pm

ejolson wrote:
Thu Aug 09, 2018 7:50 pm
Does success always lead to loss of ideals and eroding standards? There must be an example, perhaps in Hollywood, where success leads to an increased ability to preserve ideals and improve standards.
"Standards" is one place where ideals are shared, debated and developed for the benefit of everyone.

There are probably inventions and ideas which have also been shared or not patented for the common good of everyone.

But it does seem that as soon as anyone decides there is a need to protect their advantage, revenue stream or whatever, the shutters start to come down, altruism reduces.

"Logic clearly dictates that the needs of the many outweigh the needs of the few". I imagine Spock would not be considered much of a businessman.

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Re: What value are those parts?

Thu Aug 09, 2018 10:01 pm

hippy wrote:
Thu Aug 09, 2018 8:55 pm
"Logic clearly dictates that the needs of the many outweigh the needs of the few". I imagine Spock would not be considered much of a businessman.
Surely the need to have Pi at all is greater than the need to have circuit diagrams of it?

Most of the interesting circuitry is published (ie, the interfaces) -- that is much more suitable for teaching than the deep internal logic plumbing. And if you must have full circuit diagrams, they were published for the early Pis -- will anyone (except potential SBC designers) learn any more from the later ones?
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