renice123
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Re: Dead after 5.5V Input at micro USB

Fri Feb 21, 2020 10:44 pm

Drgeoff, Yes, you are right, this is flash / EEPROM memory. Someone may still remember the old memory chips with ultraviolet erasure: but in order to reduce the cost, a version without a quartz window was released, which was considered once-programmable. But craftsmen still managed to wash it - with X-ray radiation. As in Russia, they are repairing Raspberries using a vacuum separator (designed to repair smartphone displays). I’ll explain my thought, because I expressed it poorly.
So, the PMIC chip was created, which created a number of problems. Moreover, developers and sellers did not even bother to say that even a smartphone repairman can replace this chip. It seems that some reasons were thought out that you can only buy 100 pieces of microcircuits, otherwise it’s impossible in any way, otherwise something will not work there.
And I brought it up with the “cheap version” of EEPROM - everything seems to work, only once and you can’t reprogram it. This, excuse me, is a delicate way of half-deception: you seem to get a full-fledged version of the chip, but in reality it is just a rejection.
It seems to me that here on the forum almost all technical specialists. And they understand that problems with PMIC, as we all recall, have arisen constantly. And none of the developers informed users of the causes of the problems. Just buyers suffered losses. The developers did not even bother to release any document with an explanation. Yes, to the credit of RPIs, bad computers often changed.
I really liked and liked it - I saw that PRI is a company with a human face, and not just a company doing business.

In Russia, electronics are divided according to their own rules: for example, microchips are sold with acceptance 1 (the so-called acceptance of quality control department - the technical control department, when the factory tests the chips), acceptance 5 (customer acceptance, in the case of the military - the military representative controls the tests) and acceptance 9 (when only the most qualified personnel are involved in the work - for space and nuclear power plants). For example, acceptance 5/9 does not mean that the chip is radiation-resistant - resistance to special. factors are indicated in the (non-public) documentation for the chip. But there are simply electronic components that do not check, but simply write about “tolerances”, or indicate that the components are from a “batch with marriage”. (high failure rate).

But there is also a problem microcircuit, not Russian, which in a small batch suddenly and suddenly dies by itself, for no reason (we all remember that), "dies" due to the fact that the GPIO pins are located incorrectly (who is this thought of placing power contacts close? Is it intentionally that there is a danger of short circuit?), if even the second version of PMIC periodically dies for no reason, then the manufacturer could at least release some documents, like Nvidia, Nikon, Samsung and others did major players. RPI could not solder PMIC with refractory solder (because of which the repair price doubled), they could put a microcircuit in the “cradle” so that it could be changed without soldering equipment. RPI could simply send this unfortunate PMIC to people who suffered from incorrect operation and were able to replace the smd component. Could write instructions on how to properly change this chip (as this Russian guy did an engineer, but the English developers did not) This is what I wanted to say. These are all inexpensive procedures on a general scale, but forcing respect for managers and engineers.
In the end, it was possible to clearly spell out the instruction that any breakdown associated with food would be compensated one way or another.
Honestly, I did not want to write all this, so I incorrectly hinted that sooner or later these issues would still be raised. Sooner rather than later. Because the links to the constantly "dying" Raspberries of the fourth version are too numerous.
We, the buyers, do not pay our money for showing statistical charts, they say “only a few PMICs” suddenly stop working. Well, when, about twenty years ago, Fuji pierced with a microcircuit (due to improper temperature conditions in the hard drives, the microcircuit “died”), or when IBM was unable to correctly solder a video chip in the T series, this at least served as an example of how not to act .
And Nvidia simply changed explosive batteries without question and sent a completely new device. Nikon tried to resist “shutter problems,” but eventually pleaded guilty.
I’m not trying to blame someone, I’m not saying that Raspberry is a bad computer, I just read a few articles today and was shocked that the problem was somehow hushed up. This is what managers do, but this is not the approach of an engineer or technical specialist.
Maybe I'm wrong, but I express my opinion.
PS As an example, I want to say that the users of Raspberry themselves figured out the increased voltage on the power supplies, that it was not only the thin power wire that was to blame, but the incorrectly created power system — instead of a normal power connector, they used a smartphone. There is no protection, not even a fuse. Well, this suits everyone, although it leads to the fact that a lot of perfectly functioning computers are in the trash - due to the fact that an inexperienced user constantly raises the voltage, because an incorrectly programmed lightning signal shows technically correct information, but leading to confusion .
In general, these are all my “philosophical reflections” - what to do in such cases, how to act and whether it is permissible to teach students to program on devices that are not entirely correctly made.
I also do not write well in English, so my words may seem rude. I would not want that to be so perceived.

I respect the ideas of Raspberry and I was delighted when the developer suggested creating a "computer for everyone" (or even a "computer for poor people"). This is a brilliant and wonderful idea, it is humanistic (which is the most important). maybe that's why the PMIC marriage problem upsets me like that.

carbone
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Re: Dead after 5.5V Input at micro USB

Fri Feb 21, 2020 11:24 pm

Nonsense!

Timescale:
ROM program set in manufacture.
PROM one time programmable with fusible links - hence burn.
EPROM programmable can be totally erased with UV.
EAROM electrically alterable.
EEPROM electrically erasable.

renice123
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Re: Dead after 5.5V Input at micro USB

Sat Feb 22, 2020 7:01 am

I'm glad that you read Wikipedia and know that there were devices that programmed by burning wires. You probably even know about first maps? But if you are so young that you don’t remember how Intel or AMD released entire batches of "special" processors (well, or quite a recent story - the "defective processor" from Samsung of the first ODROID-XU models), then this is your problem, not mine . Being young is wonderful, but that does not mean that youth should be rude.
Good luck in overclocking the microcomputer =) https://ru.bmstu.wiki/EEPROM_(Electrica ... ly_Memory)
PS Yes, I should have written EPROM (although this is one of the subspecies of the microcircuit, which includes EEPROM), but shouldn't I be polite?

user12345
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Re: Dead after 5.5V Input at micro USB

Sat Feb 22, 2020 9:57 am

klricks wrote:
Fri Feb 21, 2020 4:24 pm
No... The system communicates with the PMIC during boot and the PMIC generates several other voltages which will not not come up if the PMIC does not initialize properly.
See: https://www.raspberrypi.org/documentati ... educed.pdf
This chip is so advanced to provide a communication port but to stupid to have a working protection like a cheap step-down converter...
Feeding 5V5 into a 5V device is wrong, but at the other side you know that defective PSUs do such...
For that there is a Polyfuse and a TVS but i guess they react to late.
The 3V3 to GND damage should not happend, its on an expansion connector and everbody assume a step-down has a protection. Second a simple Resistor at 3V3 GPIO port doesnt hurt, if you cant use a better IC.

The FET of a StepDown goes from VIN to coil to Vout, means it cant short 3V3 to GND.
If the output FET burns it shorts the output and the Input voltage and brokes all connected parts, that may gives
3V3 to GND short. If that would not the case, you could feed in 3V3 into Vout and disconnect the Coil, the PMIC would
see now a valid voltage, but doesnt regulate it.

LTolledo
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Re: Dead after 5.5V Input at micro USB

Sat Feb 22, 2020 10:10 am

5.5v on input killed the R.P.i.

R.i.P.
my condolences

whoever plugged 5.5v to the RPi, don't do it ever again...
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"

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Re: Dead after 5.5V Input at micro USB

Sat Feb 22, 2020 11:55 am

LTolledo wrote:
Sat Feb 22, 2020 10:10 am
5.5v on input killed the R.P.i.
I don't believe we have seen conclusive proof or evidence of that. The published MxL7704 datasheets show it rated for up to 5.5V operation, 6V absolute maximum. That is why I said I don't believe supplying 5.5V alone would have damaged the PMIC.

There's correlation but that's not necessarily causation.

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Re: Dead after 5.5V Input at micro USB

Sat Feb 22, 2020 12:14 pm

renice123 wrote:
Fri Feb 21, 2020 10:44 pm
Because the links to the constantly "dying" Raspberries of the fourth version are too numerous.
There appear to be very few posts which indicate unexplained PMIC or "Green light of death" failures. I have noted about 30 out of however many thousands or million sold. That seems comparable with the rate of unexplained PMIC failures on the 3B+ and is possibly fewer.

As to the issue of PMIC failure when 3V3 is shorted to something else; that is just the way it is. It ultimately comes down to "user error" and, while the Pi designers can attempt to mitigate that issue, they can never overcome it except by regulating the GPIO 3V3 separately which would mean extra cost to prevent a problem the overwhelming majority of people do not face.

renice123
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Re: Dead after 5.5V Input at micro USB

Sat Feb 22, 2020 1:33 pm

I personally can confidently talk about more than 200 “random” failures (with reference to the personal message of some RPI employees). In addition, no matter how many failures, people lost money and the argument “think, someone lost several tens of pounds!” somewhat immoral.
In such cases, manufacturers prepare the staff for repair shops, and in the best case, replace the device with a new one at the first suspicion of a malfunction.
On the forum, I see how often interrogations begin (what was your power supply? Aren't you a fool yourself? What did you do stupid to burn a computer?)
To this I will add that almost all failures are repeated with surprising accuracy in detail (that is, we are talking about a PMIC system error, otherwise the malfunctions would have manifested themselves in different ways).
Moreover, to this I will add a “legend” about the “statistical error”, which in this case sounds like this: yes, we admit that there will be some failures, but there will be few of them. After all, failures always happen and no one is to blame.
Well, if you acknowledge, then decide who will pay for the "errors." Buyer?
Also, from my work experience, I know that “classified information” implies that the situation is much worse than are trying to imagine. Why shouldn't the RPI open the PMIC problems forum and post the number of failed devices and errors that led to the death? Why not redeem or replace all broken computers and run diagnostics? If there is any strange situation and if only 30 devices have broken? This is done everywhere, all major manufacturers, if they are not trying to hide information. Why the instruction has not been created, how to replace PMIC (for example, in the workshop), why there are some strange reasons for the refusals “we can only sell a large batch” (the Chinese are selling at least one chip). All these questions are unpleasant for me, I'm used to being open. And yes, must admit, if the datasheet indicates that the device operates in the range from 4.7 to 5.5 V (this is the official datasheet for the microcircuit), then why does the 5.5 Volt cause the microcircuit to fail?
Of course, I suspect that the power supply was faulty and produced not 5.5 Volts, but more, but so far I can’t say that.
Strange things come to the point that in the last Raspberries there is no protection at all, even the most primitive, which is put in the cheapest devices (zener diode and fuse).
That is, several amps are supplied to the device and there is no any protection on the motherboard? Moreover, the current outputs hang open in the air and the plus output is located next to the minus output at a distance of several millimeters? Is this an invention for pyromaniacs or is it for children? Who was such a "brilliant engineer"? I would like to hear the arguments of this engineer in favor of such a solution (closely spaced leads under current without any insulation and fuse). Let me remind you, the device is positioned as a minicomputer for teenagers. It creates the danger of burns, fires (because of the smartphone input, where the wires are almost always thin, which causes the voltage drop to reach 0.6 V. Teenagers almost constantly overstate the voltage, and instead of branded power supplies use Chinese garbage at 20 A). And it's all even without fuses! can hang yourself!

I will add again that for a long time I did not want to write about it, because I love Raspberries and this is probably one of my favorite toys. But it seems to me that something is going wrong.
I am an adult, I use expensive and high-quality power supplies, hard drives, wires, and I even have built-in protection against overload, overheating, etc. But I'm an adult. Raspberry is a computer for teens.

I do not want to write on all these topics, because in the end it is unpleasant and it is more pleasant for me to collect a colorimeter using Raspberries now, so I will probably leave this topic for experienced engineers. Well, or let everything go as it goes - alien ships arrive and aliens “statistically” spoil the PMIC

carbone
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Re: Dead after 5.5V Input at micro USB

Sat Feb 22, 2020 2:01 pm

renice123 wrote:
Sat Feb 22, 2020 7:01 am
I'm glad that you read Wikipedia and know that there were devices that programmed by burning wires. You probably even know about first maps? But if you are so young that you don’t remember how Intel or AMD released entire batches of "special" processors (well, or quite a recent story - the "defective processor" from Samsung of the first ODROID-XU models), then this is your problem, not mine . Being young is wonderful, but that does not mean that youth should be rude.
Good luck in overclocking the microcomputer =) https://ru.bmstu.wiki/EEPROM_(Electrica ... ly_Memory)
PS Yes, I should have written EPROM (although this is one of the subspecies of the microcircuit, which includes EEPROM), but shouldn't I be polite?
More the wisdom of age I actually used ( I didn't write the code ) EPROMs in the late seventies, mainly the 2716 as Boot ROMs on Intel 8085s with Static RAM running CP/M.
Last edited by carbone on Sat Feb 22, 2020 2:34 pm, edited 1 time in total.

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Re: Dead after 5.5V Input at micro USB

Sat Feb 22, 2020 2:24 pm

renice123 wrote:
Sat Feb 22, 2020 1:33 pm
Strange things come to the point that in the last Raspberries there is no protection at all, even the most primitive, which is put in the cheapest devices (zener diode and fuse).
This is not correct. The Pi4B has a TVS diode for reverse polarity and overvoltage protection (see the schematic). It does then rely on an external current limit; if too much current is available, the TVS will fail. I don't know if it is designed behaviour, but every reported case I've seen has a short circuit failure, thus keeping the rest of the Pi4B protected (as long as the power tracks don't melt).

Incidentally, that is why it is important to provide distribution fuses when using a high-current supply for multiple Pis.

EDIT: As noted below, the subject of this post is a Pi3B+.
Series 1, 2 and 3 all had polyfuses, the details of the protection varies.
Pi0 has NO protection (what do you expect for $5 or $10?).
Last edited by davidcoton on Mon Feb 24, 2020 10:06 am, edited 1 time in total.
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renice123
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Re: Dead after 5.5V Input at micro USB

Sat Feb 22, 2020 4:52 pm

I lookedt, saw something that made me feel very bad. Maybe I misunderstood the scheme. I looked at SMBJ5.0A, Protective diode, 600W, 5V. I did not see a fuse there. It is so indeed? Or did I overlook something due to poor vision?
I thought if, for example, a 600-W protective diode shorted the line with thin wires (usually) of the power supplies, then either the power wires or the tracks on the board would start to burn.
Is it so conceived that they do not put fuses in front of the protective diode, but wait until the wires or tracks are burned out? (The Chinese like to build a track instead of resistors on the board, but here, too, progress is the same - the tracks on the board have fuses, burn themselves quietly and "save" the microcircuits from trouble, but smoke and fire are already so ... nothing).
If I understood correctly, from such circuitry you can begin to suffer from pyrophobia. And if the rest of the protection (there are still some protective circuits, galvanic isolation, what else?) Is built at the same level, then I would be afraid to give this device to children and adolescents.
However, it is possible that I misunderstood everything and everything is there - a fuse, a suppressor, and even a thyristor or a field effect transistor as a current limiter.
Or is it true that all protection is built on one diode without a fuse? This is true?
I have eight motherboards from laptops lying around at home (I bought them to solder some parts, which are too high quality). You will not believe, they are 10 years old and they work, they have six or seven fuses hanging on the internal converter. And thermal sensors, and polyfuses, and even thyristor protection and surge protection and vice versa. The same controllers are watching themselves slowly for everything in a row, up to the number of device starts.
For some reason, this is very nice to me, and even respect for the engineers who created such complex devices, although, probably, one diode could be hung as a protection and not be tormented by thought processes.
Here from the datasheet to the diode
5V typical operating voltage
6.4V minimum breakdown voltage
Maximum holding voltage 13.4 V
Maximum surge current 298 A (8 / 20μs)
Power 600 W
Operating temperature -55 ... + 150 gr.c (tj)

PS We all know perfectly well that teenagers do not use high-quality power supplies, but even lithium batteries through semi-rejected Chinese dc dc this for 20 (the other day I just explained to the young man that was madness). Which also, as a rule, do not have conventional fuses, but they explode from a short circuit like bombs. That’s what I’m thinking about right now.
On the other hand, I am glad that there are not so many teenagers with raspberries, mostly adult men have fun.

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rpdom
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Re: Dead after 5.5V Input at micro USB

Sat Feb 22, 2020 5:43 pm

renice123 wrote:
Sat Feb 22, 2020 4:52 pm
I have eight motherboards from laptops lying around at home (I bought them to solder some parts, which are too high quality). You will not believe, they are 10 years old and they work, they have six or seven fuses hanging on the internal converter. And thermal sensors, and polyfuses, and even thyristor protection and surge protection and vice versa. The same controllers are watching themselves slowly for everything in a row, up to the number of device starts.
For some reason, this is very nice to me, and even respect for the engineers who created such complex devices, although, probably, one diode could be hung as a protection and not be tormented by thought processes.
I am willing to bet that those laptops cost a little more than $35 when new. The Pi is built to a set of price points. Sometimes design sacrifices have to be made to keep that cost down.
IBM was unable to correctly solder a video chip in the T series
Yes. I know that one well. I have a T40 which still works. The video chip had to be replaced.
Unreadable squiggle

user12345
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Re: Dead after 5.5V Input at micro USB

Mon Feb 24, 2020 9:55 am

renice123 wrote:
Sat Feb 22, 2020 4:52 pm
Or is it true that all protection is built on one diode without a fuse? This is true?

6.4V minimum breakdown voltage
The Topic is about a defective PI3B+, it still has a Polyfuse but not the strange reverse Protection circuit(never sure for what this was).
Its not a secret that the rpi4 developer do strange stuff for cost reduction.
It began with a missing USB-C resistor...
Feeding LEDs that needs 1.5V from 5V, inefficent LEDs, strange wasting discharge resistors, unable to go into real standby without destroying stuff on GPIO.
RPI4 use at the same frequency more power than older models. But the CPU has less nm...
Yes there is no fuse older models has a Polyfuse before, means if the TVS Burns its a short circuit.
What now happends depends of your PSU, some have a protection, some dont. Its not uncommon, a PSU even hit my 16A/230V breaker, it had a Resistor as a Fuse but this doesnt worked well.

You see the Diode break at 6.4V-7.0V and dont protect really, the PMIC and most 5V parts are dead if your PSU output 6.0V for example.
The Topic starter dont even know what exactly the PSU has put out at the destroying point. Such PSU have a wide range under different
Load conditions.
The maximum voltage of the PMIC/Stepdown depends of the circuit around it. For example you have calculate the coils for a I/O voltage range.
Cause the Modules you can buy online often dont work for the full Voltage Range in the Datasheet.

Dont know if many teens have so much money left to buy a rpi4...

jamesh
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Re: Dead after 5.5V Input at micro USB

Mon Feb 24, 2020 11:27 am

Cost reduction. All numbers made up.

Let's say a resistor, cost $0.001. Wow, that's nothing, don't bother optimising it away.

Now, consider we have sold multiple MILLIONS of Pi4's. Lets say 5M. So we have spent $5000 on a resistor we didn't need to spend.

Let's say profit margin on a Pi4 is $5 (made up number), that's the equivalent of having to sell an extra 1000 Pi's.

So, that resistor optimising is looking pretty good now....and that just one part. Now optimize the whole board....


We spend a LOT of time optimising and beating up the supply chain to keep the BOM down, and that means keeping the end price to the users down.
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Re: Dead after 5.5V Input at micro USB

Mon Feb 24, 2020 12:26 pm

All good fun saving a dime by saving a resistor until you do what Amstrad did and get a Centronics printer port that was missing 8 pull down resistors - which made half of all users printers fail.

So the cost benefit analysis needs to work the scale of a failure into your equations. The problem is that's all guesswork. You need to build to standards first.

With the RPi4 there's about 100 users out of a million that give a monkeys about the USB-C nonsense. The problem was one shouted very loudly on social media.

Your problem was the failure to design to the spec or notice that it was out of spec during testing. That's could be due to an ambiguous spec. It doesn't help when the cheap, crap power supplies from China don't meet the spec either.
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Re: Dead after 5.5V Input at micro USB

Mon Feb 24, 2020 2:35 pm

DougieLawson wrote:
Mon Feb 24, 2020 12:26 pm
All good fun saving a dime by saving a resistor until you do what Amstrad did and get a Centronics printer port that was missing 8 pull down resistors - which made half of all users printers fail.

So the cost benefit analysis needs to work the scale of a failure into your equations. The problem is that's all guesswork. You need to build to standards first.

With the RPi4 there's about 100 users out of a million that give a monkeys about the USB-C nonsense. The problem was one shouted very loudly on social media.

Your problem was the failure to design to the spec or notice that it was out of spec during testing. That's could be due to an ambiguous spec. It doesn't help when the cheap, crap power supplies from China don't meet the spec either.
All true, we made a mistake missing off that resistor, no idea how it happened. But that doesn't negate the point of the costs savings of optimisation. Everyone does it - I worked with Samsung on cost reduced versions of some of their phones - looked the same from the outside, very different on the inside.
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Re: Dead after 5.5V Input at micro USB

Tue Feb 25, 2020 9:13 pm

jamesh wrote:
Mon Feb 24, 2020 11:27 am
Let's say a resistor, cost $0.001. Wow, that's nothing, don't bother optimising it away.

Now, consider we have sold multiple MILLIONS of Pi4's. Lets say 5M. So we have spent $5000 on a resistor we didn't need to spend.
I think the resistor(i dont need it) is required by more people than the second hdmi port.
Its importent to be energy efficent, rpi often runs 24/7.
I would pay $10 extra for a PI that waste fewer energy.
We had snow every year, it got fewer and fewer and this year no snow. Its cause people made senseless pollution.
By the way the Standby consumption of the PI4 with the default configuration should be illegal in the European Union(max. allowed is 0.5W since 2013).

cleverca22
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Re: Dead after 5.5V Input at micro USB

Tue Feb 25, 2020 10:12 pm

user12345 wrote:
Tue Feb 25, 2020 9:13 pm
Its importent to be energy efficent, rpi often runs 24/7.
I would pay $10 extra for a PI that waste fewer energy.
We had snow every year, it got fewer and fewer and this year no snow. Its cause people made senseless pollution.
By the way the Standby consumption of the PI4 with the default configuration should be illegal in the European Union(max. allowed is 0.5W since 2013).
yeah, i dont think a pi4 is capable of getting that low with only the RUN based reset

with that reset active, my pi still draws 0.96 watts, and if i then boot it and re-enter reset, it climbs to 1.33 watts while in reset

GLOBAL_EN based reset might get things lower, but then the pi has no way to turn itself back on, and you need external components, it would be simpler to just have a normal power switch in most situations

PhilBr
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Re: Dead after 5.5V Input at micro USB

Wed Feb 26, 2020 10:13 pm

The original poster said that this site was used:
https://howchoo.com/g/mwnlytk3zmm/how-t ... spberry-pi

The photos look to me as if pins 1 and 2 OR 3 and 4 are connected via the button, and either of those connections would be fatal.
The text though says 5 and 6.

Which pins were used? That's apart from the concerns about the high 5.5v supply.
Phil

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Imperf3kt
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Re: Dead after 5.5V Input at micro USB

Thu Feb 27, 2020 3:31 am

PhilBr wrote:
Wed Feb 26, 2020 10:13 pm
The original poster said that this site was used:
https://howchoo.com/g/mwnlytk3zmm/how-t ... spberry-pi

The photos look to me as if pins 1 and 2 OR 3 and 4 are connected via the button,
It's the camera angle, but it looks to me like pins 5 and 6 were used. However, that's only because I know which pins are meant to be used and looked closer, anyone could mistake them as pins 3 and 4 after only a quick glance
55:55:44:44:4C
52:4C:52:42:41

hippy
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Re: Dead after 5.5V Input at micro USB

Thu Feb 27, 2020 5:35 pm

There appear to be 17-pins in each row visible which would fit with the header being on pins 5 and 6.

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