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Pi not getting power, no image, board clicking

Posted: Thu Mar 07, 2019 11:53 pm
by sygyzy
I always have the worse luck/skill with these things. I removed the two USB ports and HDMI port and in the process pulled up some pads. I assume this is ok since I don't need to use those components anymore. The soldering of the GPIO ports seemed to go well but I didn't expand the instructions and didn't realize I was supposed to tin the DP and DM pads. I did place kapton tape to protect the rear of the usb connectors from touching the VMU board. However, I covered the whole length of the board to be safe. After I soldered the GPIO, I realized that I didn't tin the DP and DM pads so I went back and removed the tape from that section and soldered it. I checked for continuity and confirmed they are not touching each other despite the solder beads looking large.

I am hoping the power issue is literally a GPIO pin not being soldered correctly but I am not sure how to test.

When I plugged everything in, I did not get a power LED on on the Pi Zero and no image on the screen. Here are my questions.

1. Is the VMU board meant to make electrical contact with the DM and DP pads and the micro USB ports pads? I just want to make sure I put solder there when I was supposed to.

2. I was able to test a lot of the GPIO test points but there were plenty I couldn't figure out the locations to, such as:
  • * 3.3V
    * SDA
    * SDC
    * Shutdown
    * PGOOD
    * LCD DC
    * LCD MOSI
    * LCD MISO
    * LCD SCK
    * LCD BL
    * TXD
    * RXD
    * AUD BCLK
    * BATT MON
    * LCD CS
    * AUD DOUT
I assume some of these are really small pins like on the LCD header?

3. Finally, this is the weird part - when plugged in and turned on, the whole unit (not sure if it's the Pi or VMU) makes a very consistent, almost once per second clicking sound. It's very subtle but definitely happens 100% of the time and never changes frequency.

Any advice would be appreciated. If I could do it again, I probably would not have removed the ports since I am not sure I even want or needed a larger battery. Thank you.





Re: Pi not getting power, no image, board clicking

Posted: Fri Mar 08, 2019 3:05 am
by kite

Check out the pin mappings here: ... successful all the pads are labelled.

One thing, check continuity between GND and 3.3v and also GND and VCC. There should be a resistance but NOT a dead short!

Do any of the LEDs change with the clicking sound?

With it ON, measure the voltage of VCC and 3.3v, they should read as expected.

DP/DM do go to the micro USB port, but this is likely not the issue, your issue is power related!

Re: Pi not getting power, no image, board clicking

Posted: Fri Mar 08, 2019 12:13 pm
by sygyzy
Hi Kite,

Thanks for your help. I saw the test diagram and was able to test a series of connections like the directional pad, buttons A, B, L, R, ground. The ones that I have difficulty with are the ones I can't find the partner test locations for. For ones like the buttons, I know I am supposed to use the GPIO pin plus the actual pad but for other ones like the LCD ones (MOSI, MISO, RESET, etc), I am not sure where the partner pads are located.

I am also not sure what VCC means. I assume this is GPIO Pins 2 (VBATT) and 4 (VBATT). I get continuity when I measure both to GND.

I just tried measuring between GPIO Pin 1 and Pin 9 (which is labeled 3.3V and GND) and there was continuity.

With it on, I measured:

Pin 1 (3.3V B) and 9 (GND) and got 0 volts. Same with Pin 1 and the Ground connector for the L/R rear buttons.

Pin 17 (3.3V N) and 9 (GND) and got -0.630 volts. Update: odd now I am getting 0V here too.

Pin 2 (VBATT) and GND and got 0 volts
Pin 4 (VBATT) and GND and got 0 volts - I see these are 5V pads but labeled VBATT. I don't have a battery plugged in right now because I am waiting for it to arrive. I am powering through USB so I hope it's still fine to use for testing voltage?

Assuming I am measuring these correctly, it does sound like a power issue. So assuming that's the case, do I keep trying to re-solder GPIO's 1, 2, 4 until I can measure some voltage?

With the clicking sound: VMU - two red lights solidly lit and blue charging light flashing. Pi Zero W: No lights on. The flashing blue charging light does seem to be pretty in sync with the clicking but it's hard to tell if it's exact.


Re: Pi not getting power, no image, board clicking

Posted: Fri Mar 08, 2019 12:27 pm
by kite
The continuity between VBAT and GND is a problem, maybe inspect and remove any solder where you removed the USB ports or cam connection.. make sure any pads that ripped are cleaned away!

Does any area of the board get hot?

Re: Pi not getting power, no image, board clicking

Posted: Fri Mar 08, 2019 2:31 pm
by sygyzy
Ok so GPIO pins 2 and 4 (B - VBATT) should not have continuity to GND right? In that case, I wonder if somehow GPIO 4 and 6 had solder bleed into each other, causing the short?

I don't feel like any part of the board gets hot. I included a zoomed in picture of the pads where I removed the HDMI and 2 USB ports. i did not remove the camera connector. They "look" clean to me. I can take a closer look again tonight. This is going to be an uphill battle because it's a lot of guessing what it looks like under the Pi which is sandwiched to the VMU board.

With your new pre-order coming up, would you consider selling me the board only (no cables, sticker, screen, or speaker) if I can't get this working? i am already all in with a battery order, VMU cases etc, so even though this is not economical, I want a finished working product for my costs. Thanks for your patience.

Re: Pi not getting power, no image, board clicking

Posted: Mon Mar 11, 2019 4:39 am
by kite
Sounds like what is happening, the short between VCC and GND will not allow it to start at all..

Send me an email now and we can sort something out

Re: Pi not getting power, no image, board clicking

Posted: Tue Mar 12, 2019 2:49 am
by sygyzy
Hi Kite, I sent you an email to your @kiteitemshop address. I saw you opened orders again, let me know how to best proceed.