Help - SAIO board not powering pi

[mike5im5]

Hi All,

I hope this is the right place to post for help.

I'm just starting a build and have so far soldered the usb and SD points as well as the 4 GPIO pins between my SAIO 0.6 and pizero.

However, when powering up using the SAIO power and kite's test img, the pi led is not showing whether the switch is on or off. I tried de-soldering the 3.3jumper and putting power straight into the pi (with vanilla retropi img in the pi SD) and this works fine. Putting the SD in the SAIO SD slot doesn't power up however. If I resolder the 3.3 and use kite's image. Neither SD slot works for powering the pi.

I've tried resetting the solder in the SD slots multiple times but no difference so far. I'm happy to use internal SD if this is an issue but this doesn't work either when using SAIO power.

I've tested continuity between the pi USB and SAIO USB (power and data) and this seems fine. I've also measure voltage between the SAIO ground and the 4 GPIO pins. The two closest to the SD both measure 3.3, the opposite two measure slightly lower (below 3).

Any idea where the issue might lie?

Many thanks,

Mike (p.s. I can post pics if it helps). the SD point look a little messy now due to repeated reseating. Connection appear fine to the eye though.

[mike5im5]

Just a quick update. I reflowed the 2 GPIO pins with weak readings and now the pi turns on!

However, the usb hub led is not on and I'm getting ARDUINO failure in the test mode.

I've reflowed the USB connections countless times now (getting a little worried I'm overheating the contacts on the SAIO).. Still no luck.

I've tried testing the resistance between the two connections and ground.

Results:
GND -> DM a reading of around 600 when using upto 2000 setting
GND -> DP a reading of around 600 when using upto 2000 setting
DP -> DM, I can't seem to get any reading on the pi side (on the SAIO side I'm getting almost 1900 using the upto 2000 setting).

Any ideas. Have I got a short and do I need to be find an alternative way to connect the USB pins?

[mike5im5]

Another update. I mocked up a micro usb wire direct to the JST connector to see if I could power the hub that way but same results. No led and all the usb devices on the board fail the TESTER mode on Kite's retropie image.

Lost for ideas now. Any help or suggestions anyone?

[YaYa]

So to summarize :
Now the pi act led is turning green on power on.
The SD is booting fine from the SAIO.

That means that the connections from SD pads and voltage pads from the Pi to the SAIO are good. Great.

Now you don’t have USB. The usb pads are really tricky because they are very close to each other on the Pi.
Dis you cut the pad on the Pi like suggests Kite or did you use Kapton or did you do both ?
It’s likely you have a short there.

See my post, the solderings starts spoiler to see how i protected my pads... just with kapton.
Did 3 SAIO builds with this method without issues.
https://www.sudomod.com/forum/viewtopic ... 26a#p46030

[mike5im5]

I did both. Cut the right edge and used kapton tape.

Any easy way to solve shorted connections without removing the pi? Like mentioned. I’ve reflowed so many times now the saio pads around solder holes are pretty much black/gone.

[YaYa]

Unless your are VERY skilled and VERY equiped with hot air rework station you should NEVER EVER try to remove the Pi... you will end up fatally destroying the SAIO and the Pi but i presume you don’t care the Pi lol...

Instead, try to suck the tin from the pads with a pump by using a very thin tip. Try to clean the solderings... then finish with some desoldering braid. Use flux like with a pen or a brush to help.

After cleaning rework your solders with fresh tin after putting flux. Do not overcharge with tin because it may end up travelling too far under the Pi and make a short again

I hope you will succeed