Help: Repair of bricked openSprinkler PI

[Vip0r]

Hey all,

i have used the openSprinkler-Board with my PI now more than one year without any problems. I also use the pi for some home automation tasks in my garden (switch lights on/off ..) by using a 433mhz transmitter connected to the board….

First i did connect the transmitter to the free gpio-pins which are not used by the opensprinkler-board. It works without any problems but there i got only 3.3v. To improve the range i tried to use the 5v pin which is used by the opensprinkler board and shared (regarding the documentation this shared 5v out can also be used for additional hardware…)

However anything goes wrong while testing this and somehting smellt “burned”. Please note: I know this is my OWN mistake and not a problem with the borad. However i live in germany and sending a repair-request to opensprinkler.com will be very expensive for me. For this reason i hope somebody can point me in the right direction to repair the board by myself

I already tested something:

If the raspberry is NOT on the openSprinkler-Board everything looks fine: The green power-led is lightning “normal” and by measuring between 5v out (upper left corner of the board) and GND i got approx. 5v (see attachement “withoutPI.jpg”)

if i connect the pi to the shield the green power-led is lighnting very low. The rasperry is not booting and by measuring between 5v out and GND i got only approx 1,75v (see attachement “withPi.jpg”)

However if i power the pi only with a usb-power supply the pi itself is booting…

Does anybody have a idea which part could be broken?

Attachments:

1. 

   withoutPI.jpg
   

2. 

   withPI.jpg
   

[Ray]

It sounds like there is some kind of shorting on Raspberry Pi causing the voltage to drop significantly when it’s plugged in. Does your RPi boot ok if you power it by itself (i.e. without plugging into OSPi), using a USB adapter and microUSB cable?

[Vip0r]

Yes, the pi itself powered by a usb power supply is booting and working.

However i will measure the pi 3,3v and 5v gpio-outputs today to ensure the gpio-part of the pi is okay.

I also recognized the opensprinkler-board (WITHOUT the raspberry-pi connected) does NOT output 3,3v on the gpios? (see my screenshot: i mean the pin below of the marked 5v output)

Can anyone confirm that?

[pablo666]

I think diode SS24 neer AP1501 is broken It should have 0,2V dropout (shotky diode)

[Vip0r]

Thx pablo666,

i will give it a try and replace this diode. Hopefully i can unsolder the old and solder the new one without bricking the hole board ^^

Any chances you can explain a little more your toughts? (by the way: with a bit of fantasy i can see a small “bubble” on the diode SS24 🙂 )

[pablo666]

step down converter looses its current efficiency with broken diode. Also AP1501 may be broken to

[Ray]

@Vip0r: OpenSprinkler Pi board does not output 3.3V — it only outputs 5V and it gets 3.3V from Raspberry Pi.

[Author]

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