Bridged Pads

[Lphillimore]

Bit of a nightmare.

Pretty much finished my first build however kept getting continuity issues with the 5V and GND pads on the top right of the PCB. A dab of the soldering iron on either pin saw the multimeter buzz once more.

Thought this was sorted and had the pi booted for a prolonged period earlier with no dramas, transferred ROMs etc. All fine.

Completed the rest of the build and was just putting the screws in and it would no longer boot. Hadn't touched the solder joints again up until now. Retested I noted that the main VCC power pin where I'd connected my switch and USB Soundcard was not connecting when tested with multimeter.

Again dabbed the aforementioned pins and viola the pi booted...but quickly cut out.

Long story short the 5v and GND are now bridged ad confirmed by multimeter and lack of life on pi.

Not sure of a way back now. Fresh build?!

[Pirate]

Hmmm have you tried using a heat gun to re-solder the pins? Last time I had this issue I managed to get my pins unbridged by using a heat gun and a solder sucker

[Helder]

Are you talking about the Pi GPIO pins soldered to the PCB? If so you probably used a little too much solder but you can try using liquid flux like in a flux pen and douse the area with flux and use a clean iron tip and put it in each hole that is bridged and it should suck up extra solder to the tip. Be sure to clean it after each hole is reheated, also post some pictures so I know for a fact the problem area and use 63/37 solder if you aren't already.

[Lphillimore]

Thanks, guys. Yes, I'm talking about the Pi GPIO pins soldered to the PCB - agree this would only be down to too much solder - I was worried about this when re-heating the pins but the odd thing was that unless i did this there was no continuity between them.

Perhaps this isn't the issue after all.

SpoilerShow

Testing setup.JPG (203.34 KiB) Viewed 7912 times

I am definitely using 63/37 solder

Oddly, this morning when using the multi-meter, neither the ground or 5V register now a connection. Yesterday i got continuity on them individually and also when alternating between them. So I'm not 100% they are bridged. I have recorded a video testing all pins to highlight this as below.

https://www.dropbox.com/s/47aqrv28ew1mx ... 6.mp4?dl=0

When i boot the pi from battery now - screen is very dimly lit - no activity on Pi.

When i plug 5v directly into Pi, activity light blinks and screen lights up white. That said, dimmer than normal. Pressing 'Start' makes the screen brighter but again, no change in activity on screen.

https://www.dropbox.com/s/kujnbtej929cs ... 7.mp4?dl=0

Additionally, between any of the GND pads on the PCB there is continuity. As expected.

There is no continuity between either of the VCC pins on the PCB however.

Here is an overview pic of wiring.

SpoilerShow

overview.JPG (117.51 KiB) Viewed 7912 times

Trying to work out how to track down the issue.

[Helder]

VCC under the 8pin connector is the 3.3v connection the other VCC is where the battery goes into the 5V line. Look at the other thread I stickyed at the top of this forum for a possible solution. Also check power on the lcd board and continuity for grounds and other pins to be sure the screen is getting the proper signals properly.

[Lphillimore]

VCC under the 8pin connector is the 3.3v connection the other VCC is where the battery goes into the 5V line. Look at the other thread I stickyed at the top of this forum for a possible solution. Also check power on the lcd board and continuity for grounds and other pins to be sure the screen is getting the proper signals properly.

Thanks, Helder. Have connected a wire between GND and pin2 as per sticky but no joy as yet. Current situation is that battery will not power system but direct 5v into pi will, albeit white screen. This is now bright and no longer reacting to Start or Select buttons.

Written a new image to SD card and retracing steps etc. Have re attached ribbon cable at all points, too. Have also used flux pen to reflow all pins. Continuity on all pins is now good but still solid white screen.

Retested by hooking up to HDMI on my TV and output is partially legible but mainly garbled. Assuming this is related.

Investigation continues

[Helder]

I had one just now that the continuity tested ok but likely was a weak connection on the 5V GPIO and wouldn't power from battery but once I redid the point it started to power by battery. Good to check if power is going to all parts with the meter.

[144TECH]

Inspect the coil top, next to the camera connector clip, (if you use a zero W) many times this thing cracks on the top, altough it can be fixed easy, if it is broken. (i'm assuming this because you said when screwing it together stuff started, i've had that one time too lol)

[Lphillimore]

Cheers, both. Will assess these options later. Hopefully get it sorted . Will hit the nail on the head soon I'm sure