Psychokiller1888
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Raspberry pi 3B + 7'' official touch screen power supply

Fri Mar 30, 2018 11:15 am

Hi!

I have quite many raspberry pi 3 and a few touch displays. I also have the official power supplies, 5.1v, 2.5a micro usb (https://www.pi-shop.ch/steckernetzteil-microusb-5v-25a)

I do connect the whole like:

- Power supply to screen micro usb power in
- USB to micro SUB cable from Screen USB power out to Raspi micro usb power in

I also tried to
- Power supply to raspi micro usb power in
- Raspi ground and 5v pin to screen power pins

In both configurations I end up with the nice yellow ligthning bolt in the top right corner, indication power insufficiancy

My question is, what power supply do I need then to run my raspi, the touch screen (and a respeaker 4)? 5 volts obviously, but then what? 3 amps? 3.5 amps? Anyone can link to a good product (please avoid cheap material from China that might burn after a night plugged in) that ships worldwide? (I'm in Switzerland)

wildfire
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Fri Mar 30, 2018 1:53 pm

3B or 3B+?

If 3B+ it's likely you have an older version of software which is causing the issue. In either case so should update your OS on a regular basis.
Scotty never said "I canae give her any more Captain, She'll blow".
B'Elanna Torres however did say "Get the cheese to the sickbay" :?:

Psychokiller1888
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Fri Mar 30, 2018 6:21 pm

3B, 3B+ is coming next week

My OS is up to date for sure

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davidcoton
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Fri Mar 30, 2018 8:25 pm

I have a Model 1B+ and official display. I found I could not power one from the other, either way. I solved the problem by using a supply with twin 5V 2.5A outputs and two USB cables.
My solution may be overkill. YMMV.
"Thanks for saving my life." See https://www.raspberrypi.org/forums/viewtopic.php?p=1327656#p1327656
“Raspberry Pi is a trademark of the Raspberry Pi Foundation”

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Re: Raspberry pi 3B + 7'' official touch screen power supply

Fri Mar 30, 2018 8:33 pm

Power supply to the Pi, and then linking out to the display from the 40 pin header works fine for me with a 3B+ and display, using the official power supply to power it.
Have you got any other USB devices hanging off the Pi that could be consuming moderate amounts of power?

Almost certainly it is loss in the cable that is your issue. Increasing the current that the PSU can provide will not help in this case as the voltage will still be low (it'd be worth measuring it with a multimeter to confirm just how bad it is).
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Psychokiller1888
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Fri Mar 30, 2018 8:43 pm

As I said, I have a respeaker 4 on the 40 pins as well

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karrika
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Sat Mar 31, 2018 5:05 am

Buy a good USB cable intended for powering things. You want thick copper cables - not thin aluminium cables with copper coating.

Avoid DC buck converters. They produce a lot of noise that affects the touch screen. It becomes sluggish and non responsive.

Psychokiller1888
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Sat Mar 31, 2018 5:34 am

So based on all the answers here I understand that I don't need more amps, but a better power supply, still 5.1v and 2.5a?

fruitoftheloom
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Sat Mar 31, 2018 5:58 am

Psychokiller1888 wrote:
Sat Mar 31, 2018 5:34 am
So based on all the answers here I understand that I don't need more amps, but a better power supply, still 5.1v and 2.5a?

Official PSU

https://www.raspberrypi.org/products/ra ... er-supply/
Adieu

Psychokiller1888
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Sat Mar 31, 2018 6:19 am

Ok, gonna give it a shot. I just hope the bolt lightning will go for good...

wildfire
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Sat Mar 31, 2018 3:04 pm

Psychokiller1888 wrote:
Sat Mar 31, 2018 6:19 am
Ok, gonna give it a shot. I just hope the bolt lightning will go for good...
Hmm, Didn't you say in your first post that you already tried the Official power supply?
Psychokiller1888 wrote:
Fri Mar 30, 2018 11:15 am
I have quite many raspberry pi 3 and a few touch displays. I also have the official power supplies, 5.1v, 2.5a micro usb
Yeah, I thought so.
Scotty never said "I canae give her any more Captain, She'll blow".
B'Elanna Torres however did say "Get the cheese to the sickbay" :?:

Psychokiller1888
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Sat Mar 31, 2018 3:14 pm

Looks like not, I have lined the one I'm using that was averted as the official. The one that was linked to me in an answer is another I found in Switzerland and now bought. I just can't understand why it would solve a powering issue.... Not enough current is just.... Not enough current. But I also bought a 3a psu in case, just because I sont believe using another same spec psu could change anything

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davidcoton
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Sat Mar 31, 2018 4:19 pm

Just to be clear, the lightening bolt indicates a lack of voltage.
This may be because the PSU runs out of current, so the voltage drops.
Or it may be because of inadequate cables, with a resistance high enough to loose too many volts at the operating current.
In either case, the official PSU is properly specified, designed and built to provide 2A5 at between 5V0 and 5V2 at the USB connector (ie after the attached cable).
So it is a step in the right direction. As in my previous post, it is not the only possible solution, but it stands a better chance of working than just random 5V 2A5 PSUs with unknown cables.
"Thanks for saving my life." See https://www.raspberrypi.org/forums/viewtopic.php?p=1327656#p1327656
“Raspberry Pi is a trademark of the Raspberry Pi Foundation”

Psychokiller1888
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Sat Mar 31, 2018 4:44 pm

I just tested my PSU, between pin 1 and 4 on the micro usb end, that means as you said, after the cable, I have 5.22v....

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davidcoton
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Sat Mar 31, 2018 5:15 pm

Psychokiller1888 wrote:
Sat Mar 31, 2018 4:44 pm
I just tested my PSU, between pin 1 and 4 on the micro usb end, that means as you said, after the cable, I have 5.22v....
Yes, but does it maintain that voltage while supplying the full load of Pi and screen?
Test (very carefully -- shorts can kill your Pi) the voltage on the GPIO connector, pin 2 (5v) and pin 6 (Gnd), while trying to run the Pi, both with and without the screen connected.
"Thanks for saving my life." See https://www.raspberrypi.org/forums/viewtopic.php?p=1327656#p1327656
“Raspberry Pi is a trademark of the Raspberry Pi Foundation”

Psychokiller1888
Posts: 35
Joined: Fri Mar 30, 2018 8:15 am

Re: Raspberry pi 3B + 7'' official touch screen power supply

Sat Mar 31, 2018 5:27 pm

Nope, I drop, with pi and screen only, to 4.75v, adding respeaker 4 goes to 4.65. Did not bother to add a camera on it to test more... Next step is complaining to my supplier that was selling it as the official... And wait on the official PSUs to arrive, damn easter weekend...

Psychokiller1888
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Wed Apr 04, 2018 10:06 am

@davidcoton

I just spent 50 bucks buying 2 pi official PSUs..... And it's EXACTLY the same....

wildfire
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Wed Apr 04, 2018 1:48 pm

Where on earth are you spending 25 bucks for an official raspberry PSU?

Link please.
Scotty never said "I canae give her any more Captain, She'll blow".
B'Elanna Torres however did say "Get the cheese to the sickbay" :?:

Psychokiller1888
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Wed Apr 04, 2018 2:27 pm

Welcome in Switzerland. But a point, it's 20usd, not 25, wrong change rate, sry, then count the postage fees, 9chf = 9.4usd = 49.4usd 2 psus

https://www.pi-shop.ch/steckernetzteil-5v-2-5a-schwarz

wildfire
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Wed Apr 04, 2018 2:45 pm

Thanks, and I thought we (UK) were being ripped off $-£ exchange rate. Remind me never to shop in Switzerland but surely you can buy cheaper overseas.

EDIT:

Duh, I forgot you're landlocked. Let's settle with elsewhere.
Scotty never said "I canae give her any more Captain, She'll blow".
B'Elanna Torres however did say "Get the cheese to the sickbay" :?:

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mahjongg
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Thu Apr 05, 2018 6:00 pm

soft delete, because user choose to start a new topic

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mahjongg
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Re: Raspberry pi 3B + 7'' official touch screen power supply

Mon Apr 09, 2018 3:41 pm

Restored, after moderator discussion.


P.S. The rest of the discussion was continued here:
https://www.raspberrypi.org/forums/vie ... 8&t=210171

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