Pi doesn‘t boot

[beardedviking]

Okay, I have the following problem:

I soldered my Pi Zero to the button PCB and checked all pins and test pads with my multimeter. I didn‘t find any problems so I connected the screen to the PCB, inserted a fresh new SD card with the latest image and connect the power directly to the Pi. The status LED flashes green once and that’s it. The Pi wouldn‘t boot any further and the screen stays blank.

Did I fry my Pi?

I tried the SD card in another Pi Zero and it worked. I tested this with a Raspbian, a standard Retropie and the MintyPi image. Only strange thing is that the MintyPi installation would not give me an image over HDMI. But I can tell from the flashing of the status LED that the Pi is booting.

I tested all GPIO pins and the test pads. Nothing wrong here.

I checked the ribbon cable but it fits perfectly.

Any more ideas?

I don’t want to buy a new Pi and PCB set. Please help me.

[dryja123]

Hey, could you post some pictures of your soldering? Also, what are your voltage readings on the PCB?

[beardedviking]

I will upload a photo later (it’s 3 in the morning and I’m about to catch a few hours of sleep ). Can you please explain how I would do the voltage readings?

[dryja123]

I will upload a photo later (it’s 3 in the morning and I’m about to catch a few hours of sleep ). Can you please explain how I would do the voltage readings?

There may be a link to a power troubleshooting guide in my signature

[beardedviking]

Haha, sorry, I didn’t see that. Great guide by the way.

I checked and I had a reading of 5.2V on the 5V test pad and 3.31V on the 3.3V test pad. I then did the same with the corresponding GPIO pins and received the same readings. So this is kinda good news so far, right?

Here is the image of the soldering:



The reason why I think the Pi might be broken is that when I put the same SD card into another Pi Zero I can see the status LED flash like its booting although I can’t get any output over HDMI.

[beardedviking]

One idea I haven't tried yet is to start the Pi without the screen connected and see if that changes anything. I don't think it will but you never know, right?

Btw: what is the RHT (RMT?) next to the D/C and 3.3V Pins? There seems to be no test pad for this one.

[beardedviking]

Okay, strange thing. I disconnected the ribbon cable, plugged in the power supply and suddenly the status LED indicated that the Pi was booting. After that I connected the ribbon cable again (and I made sure it is connected correctly), plugged in the power supply and again the Pi booted and the screen showed the RetroPie Logo. Woohoo! So far so got. Shortly after that the screen went black and the status LED would flash only occasionally until it stopped doing anything. After a while (like 3 to 5 minutes of "silence") I unplugged the power supply and re-plugged it. But nothing happened.

So the good news is, the Pi and the PCB are not fried, they seem to work. The bad news is, there's still something going on. Could it be a loose contact on the power port of the Pi? I tested the voltage while the Pi seemed to do nothing and the readings where still 3.31V and 5.2V, so there is power and there is enough power.

Any ideas? Anyone?

[rodocop]

for you question, RHT, is short for right, its the connection for the right arrow on the d-pad.

So the pi and screen work, but only intermittently? Likely a wiring issue then. Re check continuity on all screen GPIO connections. Place one end of the multimeter on the GPIO pin, and then place the other on the test pad on the PCB. If that's good, then move the multimeter to the test pads on the screen board. You want continuity from the GPIO all the way to the screen board.

Also do the same for all other test pads, and pay close attention to the ground, i've found that is the hardest one to get a good connection on.

[beardedviking]

Thanks for your answer. I already checked for continuity twice or trice even, but I did it again because… you never know. Every connection from the Pi to the board and on to the screen gives me a loud and clear beep. All ground pads react perfectly. I checked every pin for shorts with the surrounding pins and found nothing. When plugged to the power source all voltage readings are good.

Since it worked for a few seconds as mentioned before I tried it two more times but the Pi's status LED does nothing, as if the Pi is dead. I don't know what else to do. I couldn't even desolder it to try the board with another Pi because I have no desoldering station.

This sucks.

[Helder]

Read my response in the thread below this one about a short to GND and see if that's the issue.