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Usual problem - USB power has gone.

Where is the fuse located on the board? The reduced schematics on the RPi webpage does not show the USB at all.

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  • Why do you want to know?
    – Milliways
    Sep 20 '18 at 9:46
  • I want replace it with something having a better rating Sep 20 '18 at 9:49
  • If you can't find the fuse (which is clearly visible and labelled in the bottom right hand corner near the power connector) it is doubtful you could replace it - even if you could find a replacement - which would be a poor idea anyway as it is doubtful if the board traces could carry more than 2.5A. NOTE the fuse is clearly labelled on the schematic.
    – Milliways
    Sep 20 '18 at 9:58
  • I am not asking about the F1 fuse, Only the one protecting the USB! Sep 20 '18 at 10:05
  • There isn't one! USB Current is supplied through a Current-Limited Power Switch (AP2553?)
    – Milliways
    Sep 20 '18 at 10:05
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As there is no information about it on the RPi website and something definitely has blown up on the board cutting the USB 5V supply, I have decided to measure where the the "raw" USB input is and hardwire it on the board.

Here is my workaround (the wire should be shorter):

enter image description here enter image description here

PP2/PP3 <-----> PP27

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  • Don't you risk "starving" the RPi? Sep 20 '18 at 11:54
  • @GerardH.Pille I do, but the another choice is to bin the RPi. But the proper power + 330u cap will probably sort that problem out. Actually I have connected my USB device (it sources about 300mA) - the RPi is quite heavily loaded ~90-95% but the power looks OK (it is connected to the scope now) Sep 20 '18 at 11:58
  • You do have the problem even if the RPi is not "loaded" ? Sep 20 '18 at 12:01
  • The problem is that USB power is dead. And this test was only to check if I will not starve my RPi Sep 20 '18 at 12:06
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On this page there is a nice picture.

https://www.petervis.com/Raspberry_PI/Raspberry_Pi_Dead/Raspberry_Pi_Fuse.html

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  • but it is not the RPI 3 only the older version. I have found a lots of old RPi information but nothing about the RPI 3 B (not B+) Sep 20 '18 at 9:40
  • Sorry. Do you mean the 3B does not have the fuse as the 3B+ has? Sep 20 '18 at 9:55
  • And the yellow 3592 so close to the usb power port? raspberrypi.org/app/uploads/2017/05/… Sep 20 '18 at 10:00
  • I try t find that one which cuts the USB power. Sep 20 '18 at 11:59
  • That may not be a fuse at all. Perhaps the Pi can manage how much power may go to the USB connectors. Sep 20 '18 at 17:32
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An addition to the soldering solution:

It is PP1/PP2 <-----> PP27

PP3 is GND, so don't connect this with PP27.

See full list of test pads https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=89522&p=628505&hilit=pp12%2Bpp13#p628505

Raspberry PI disables power on USB ports on reboot. With this modification there is always power on USB port and no "hardreset" of usb devices by just rebooting possible.

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