Screen flickering even with 5v conversion

[Bugmaster]

Hi folks... Iam building my GBZ and having strange flicker issues with the screen even with 5v conversion ... I already tried the search function but couldnt find any solution and now Iam lost :-/
My setup consists of Cambles PowerBoost SafeShutdown, with an PowerBoost 1000c and Helders newest AIO with the integrated powerstrip.

- I have the gearbest screen mentioned in the wiki
- I did the 5v conversion as pictured in the wiki (and discussed several times in the forum); after a few attempts with several resolderings its not the prettiest anymore but tested with a multimeter and no bridges... I know the wire colors are not accurate

Heres my attempt:


Red - VCC
White - GND
Blue - Pi AV
5v Conversion: white cable bridge from VCC to pin3 of the bm1410a (I also tried to solder VCC directly to the pin)


So whats my problem?
- If I connect the screen via the AIO powerstrip (with the PoowerBoost and the SafeShutdown) measures show 5.14v on all powerstrip pads, the red VCC screen contact and the 5v screen bridge ... the screen didnt show anything; same thing with an USB power supply and directly soldered to the screens VCC and GND
- If I connect the screen directly to an USB cable/ port the screen is flickering and shows a picture for a second; measures shows unstable 3.97v with some drops below.



Any ideas?

[kirestus]

i would maybe take another crack that the mod. try covering the solderpoints on the pins with some heatshrink or electrical tape,

my money is on the 5v mod not working correctly.

did you try it before the mod, if so what was the result like?

[kirestus]

if that fails you could try running it straight to the pi bypassing the aio board for troubleshooting, you may need to use a thicker gauge wire from the powerboost.

i had a similar issue

[Bugmaster]

Because Iam building two GBZ I have another screen ... with the same mod and issue

I also tried the following...

• # 1. resoldered with VCC and GND wires from an old pc power supply, so a real heavy gauge this time ... black screen / with USB power still flickering
  # 2. I also tried the second screen input, because some post mentioned that the flicker went away ... black screen / with USB power still flickering
  
  
  # 3. I completly removed the AIO and just have "battery (not connected in the pic) -> powerboost -> screen" ... again, black screen and flickering with USB power
  
  
  # 4. I soldered directly to the pi's 5v and GND...
  ... measured the pi's 5V pin shows a little less than 5V
  ... if I attached the screen Ive got a full picture with some brightness flickering; measured I can see 3.6V and during the flickering drops to ~3V ... thats the point where the pi restarts (I think because the screen pulls to much the pi drops under his comfort zone and due power cut restarts)

[kirestus]

You try running your power strip off the + and - where you solder on the optional USB port. That's how I did mine take a look at wermys guide for the og version

[kirestus]

sorry my last post was kinda unclear

on the powerboost1000c
You try running your power strip off the + and - where you solder on the optional USB port. That's how I did mine take a look at wermys guide for the og version

if that doesnt work try running the screen by powering the pi up from its micro usb port, and bypassing the powerboost, and soldering the screen input to the pi and let me know your results

[Rolen47]

What's the amp rating on your USB power adapter? Adafruit recommend using a USB adapter that can provide at least 2 amps. This is the one that I use, haven't had a problem with it yet.

What gauge are your power wires? The wires providing power need to be 26 or 24 gauge. Thin gauge wires such as 28 or 30 have a lot of resistance with high current and will cause voltage drops. This is also true for the USB cable going from your adapter. Some USB cables are cheaply made with thin wires, make sure you have a USB cable that is labeled as being "quick charge" compatible or that it's labled to handle up to 2 amps. Here's an example

[Armstrs]

Scratch that. I looked up your chip and pin 3 is the correct output pin.

[Bugmaster]

@kirestus:
- tried soldering to +/- of the additional USB port ... same issue (both points show the exact same V of 5.15)
- soldered screen directly to pi's +5 and GND ... screen is working until emulationstation boots, then the pi restarts and the screen goes black ... I think because of V drops from ~4v to ~3.4v

@Rolen47:
- I tried several USB power supplies 5v/1A
- Even several wires (old pc power supply = 20AWG / normal wire with 22AWG) and because of the short length in combination with the low V cable resistance shouldnt be an issue (measured ~ 0,2ohm despite length)

@Armstrs:
- based on http://www.bookly.com/images/BM1410A.pdf ... yup, pin3 is the correct one other screens (like the rear camera ones) use another chip where the pin layout is different
- pin2 ist the vcc input and also shows correctly 5v

[fcib]

Don't use a jumper. Just move the 5v wire straight to the output of that chip (i think pin 3)