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Imperf3kt
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desoldering USB

Mon Sep 04, 2017 1:40 am

I found many threads via googling, but nothing was very clear so I was hoping for an answer from an engineer.

What I aim to do is completely remove all four USB A ports and replace them with 2.54mm pins. Two of the ports (by means of a header) would be repositioned inside a case with the remaining two, either unused or wired up as a USB to SERIAL adaptor so I can make use of a modified Synaptics touchpad, leaving the GPIO free for other uses.


My doubts about this are is anything near these ports susceptible to damage from heat and can I do the same with the unused ethernet port.
I do not intend to salvage the parts, destruction is a viable method of removing them.

No, I cannot make do with one USB port, so waiting for a Pi3A is also not an option. I also don't care about warranty - it would cost more to return it than to buy a new one.

However, to avoid this in its entirety, is it possible to buy or arrange to buy an RPi3 without these parts installed at all?
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wh7qq
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Re: desoldering USB

Mon Sep 04, 2017 3:04 am

Unless you are truly good with a soldering iron and have very good equipment as in production desoldering gear, any messing around with the board with high temps is a fools errand. It is really easy to lift foils when applying heat and the tension to remove hardware.

drgeoff
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Re: desoldering USB

Mon Sep 04, 2017 8:00 am

I've never had the need to do it but this is how I would attempt it.

Carefully use a Dremel or equivalent to completely cut apart and remove the body parts of the USB and ethernet sockets until you are left with individual pins and pieces of metal still soldered, each at only one point. Then use a soldering iron to remove those.
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rpiMike
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Re: desoldering USB

Mon Sep 04, 2017 8:16 am

How about just using USB extension cables ?

25cm Dual USB 2.0 A female socket panel mount to 2 USB A male extension cable https://www.amazon.co.uk/dp/B00NIH1PZ6/ ... RzbD80A58N

PiGraham
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Re: desoldering USB

Mon Sep 04, 2017 8:46 am

You can get low melting point solder for removing SMD components. E.g. Chip quick. http://uk.farnell.com/chip-quik/smd1/re ... 0000115787

You an find similar materials on eBay for cheap.

Although ChipQuick is marketed ro SMD removal it's just a way of melting solder joints at a low temperature and should work as well on through hole RJ45 as SMD chips. You can get a big bead of solder that touches all the pads at once and ease out the connector. NB I have used ChipQuick but not on RH45 connectors. I can't promise it will work but it seems like it should.

An alternative is a hot air rework gun to heat all the pads at once but there is more chance of board damage that way.
A third option is to dismantle the connector to get at individual pins and then desolder and remove those one at a time. There is a high chance of damaging the board unless you can find a way to dismantle a shielded RJ45 very gently.

drgeoff
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Re: desoldering USB

Mon Sep 04, 2017 8:54 am

The USB sockets are merely connectors. Unless you want to remove them to save space there is no reason why they cannot be left in situ and wires run from their solder
pads on the bottom of the board to additional sockets elsewhere. But don't try to use both of any pair (on board and additional) at the same time.

The above is not the case with the ethernet socket. It contains 'magnetics' and you cannot have two of them in parallel.

If you had knowledge of an assembly line, testing stage and distribution channel like that of RPis you would realise that buying a few without those connectors is out of the question.
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drgeoff
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Re: desoldering USB

Mon Sep 04, 2017 9:00 am

PiGraham wrote:
Mon Sep 04, 2017 8:46 am
A third option is to dismantle the connector to get at individual pins and then desolder and remove those one at a time. There is a high chance of damaging the board unless you can find a way to dismantle a shielded RJ45 very gently.
Dremel with cutting disc and RPi firmly secured - NOT held in your other hand. Fortunately the sockets are at the edge of the board which makes it much easier to attack them without accidentally damaging other components.
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Imperf3kt
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Re: desoldering USB

Mon Sep 04, 2017 9:53 pm

rpiMike wrote:
Mon Sep 04, 2017 8:16 am
How about just using USB extension cables ?

25cm Dual USB 2.0 A female socket panel mount to 2 USB A male extension cable https://www.amazon.co.uk/dp/B00NIH1PZ6/ ... RzbD80A58N
I'm trying to make the board smaller, but thanks for the suggestion anyway.

drgeoff, as I understand it, the PCBs are made in a big sheet in a facility located in communist China (PRC) with the SOC coming from Taiwan.
These sheets of multiple Pis are shipped to Wales, UK, where final assembly is conducted which involves splitting the boards off the sheet, cleaning the edges and installing the peripheral connections such as the RJ45 socket or USB header socket.
4000 of these units are produced every day.

No?
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davidcoton
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Re: desoldering USB

Mon Sep 04, 2017 10:19 pm

Imperf3kt wrote:
Mon Sep 04, 2017 9:53 pm
as I understand it, the PCBs are made in a big sheet in a facility located in communist China (PRC) with the SOC coming from Taiwan.
These sheets of multiple Pis are shipped to Wales, UK, where final assembly is conducted which involves splitting the boards off the sheet, cleaning the edges and installing the peripheral connections such as the RJ45 socket or USB header socket.
4000 of these units are produced every day.

No?
AIUI, no (though I may be wrong...).
The Sony factory at Pencoed, Wales has a complete assembly line (maybe more than one). All components are loaded, soldered, boards tested and packed.
Same thing happens in a Chinese factory (possibly more than one), and in Japan.

SOC and other components could come from various countries, it's a very international trade.
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klricks
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Re: desoldering USB

Mon Sep 04, 2017 10:21 pm

Imperf3kt wrote:
Mon Sep 04, 2017 1:40 am
....However, to avoid this in its entirety, is it possible to buy or arrange to buy an RPi3 without these parts installed at all?
There is a custom order service from the RPi manufacture: https://www.element14.com/community/doc ... on-service
Note that the minimum order is 5000 units + consultation / engineering fees.
Otherwise you must buy complete units and do your own rework.
Unless specified otherwise my response is based on the latest and fully updated RPiOS Buster w/ Desktop OS.

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rpdom
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Re: desoldering USB

Mon Sep 04, 2017 10:30 pm

The bare boards may be manufactured in the PRC, but they are (IIRC) made in small sheets of six Pi to a sheet (more for the Zero).

As others have said, the components are all added in one of the productions lines, either the main Sony one in Wales, the new Sony one in Japan or one of the other ones (Egoman/Embest?) in the PRC.

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Imperf3kt
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Re: desoldering USB

Mon Sep 04, 2017 10:45 pm

klricks wrote:
Mon Sep 04, 2017 10:21 pm
Imperf3kt wrote:
Mon Sep 04, 2017 1:40 am
....However, to avoid this in its entirety, is it possible to buy or arrange to buy an RPi3 without these parts installed at all?
There is a custom order service from the RPi manufacture: https://www.element14.com/community/doc ... on-service
Note that the minimum order is 5000 units + consultation / engineering fees.
Otherwise you must buy complete units and do your own rework.
Well, I could potentially order five units as what I am making has some very interested followers, but 5000 is out of the question.
Thank you for the info. It was more than enough to sate that line of thought.

So that leaves just manually removing the parts via dremil + cleanup or using USB extension cables and forcing a redesign of my case (which is already too large for my intended use)

But my main question is, apart from the obvious potential to lift pads and tracks, are there any components susceptible to heat damage via this method?
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klricks
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Re: desoldering USB

Tue Sep 05, 2017 12:06 am

Imperf3kt wrote:
Mon Sep 04, 2017 10:45 pm
........So that leaves just manually removing the parts via dremil + cleanup or using USB extension cables and forcing a redesign of my case (which is already too large for my intended use)

But my main question is, apart from the obvious potential to lift pads and tracks, are there any components susceptible to heat damage via this method?
I would just cut the shield and plastic bits with side cutters and then un-solder the 8 through pins one at a time with a soldering iron.
Unless specified otherwise my response is based on the latest and fully updated RPiOS Buster w/ Desktop OS.

alphanumeric
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Re: desoldering USB

Tue Sep 05, 2017 11:39 am

Would using an A+ instead of a 3B be a viable option? No Ethernet port and only the one low profile USB Port. Single core CPU though. Just a suggestion. If you need the performance of a 3B go back to plan A.

If I was to attempt it. I would carefully cut the shell apart/off so you can unsolder one pin at a time.

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RaTTuS
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Re: desoldering USB

Tue Sep 05, 2017 11:56 am

https://www.youtube.com/watch?v=iZ3ajIo ... u.be&t=168 show you how to desolder everything
How To ask Questions :- http://www.catb.org/esr/faqs/smart-questions.html
WARNING - some parts of this post may be erroneous YMMV

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alphanumeric
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Re: desoldering USB

Fri Sep 08, 2017 7:12 pm

Bilge Tank 107 - The World's Slimmest Raspberry Pi 3
https://www.youtube.com/watch?v=NQvRNU3sTtI

mindwave
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Re: desoldering USB

Tue Aug 11, 2020 12:27 pm

i found a guy on etsy who did it for me, just because i wasnt sure of what it wouyld do, this was on an rpi4 the one thing i didnt do that i wish i had was run wires from the pads, as someone suggested, so i could still have access to the ports.

i like the videos posted, THOSE are very helpful\\

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