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NesPi Case Power Problems

  • I wanted to add some findings to the power issues on this case. I followed @iggy 's solution in another thread and it was super successful.

    I had both a Canakit adapter 2.5a and a Pi Hut 2.5a power supply. I don't know if some of it is just bad luck or manufacturing, but I had power issues even scrolling through my game list ( which is a video preview list, not just screenshots/box art).

    I decided to solder new larger 22 awg pos & neg input power wires (the ones from the power input/buttons board on the case that runs to the other board which sits under the usb/ethernet circuit board). Replacing these wires cured my lightning bolt issues. It seems that the other wires are fine for voltage but as many speculated, the main power input wires were not thick enough and too much current/voltage was lost after running through the power/reset button board. All seem so be well and am even playing N64 games without any voltage issues. This is with a gampade and a keyboard plugged in, with wifi on, and a third wireless input (ps3 controller ) all being active at once.

    Hope this helps.

  • Still having the issue where a power down followed by pressing the power button the light stays on just dim, of course unplugging the HDMI kills the light but why do I have to unplugg the HDMI cable everytime to make the light turn off after shutting off the NESPI case

  • @valhalla_pi that is normal in power down mode. The Pi is just sleeping. Unless you are using a mausberry circuit or similar hardware that truly cuts the power, this low power hibernation is as good as you can get.

  • @Valhalla_Pi

    Have you tried another screen/cable?

    I have seen this behavior as well with my NESPi case, but it only occurred on an HP monitor I was using that also has powered speakers attached to the monitor. I was using a DVI-HDMI cable and had the same strange (dim power light) issue when I powered off. I believe that at times, if I simply powered off my monitor it would kill the dim light, but removing the HDMI cable always did the trick.

    When I switched to my TV (Sony - regular HDMI cable) and powered off, the light went right out (like I think it should).

    I also saw the lightning bolt icon when connected to that monitor (after using it to setup the system. I probably used that monitor for about 3 hours on and off (different days), but it was only after a couple of days that the lightning bolt started appearing.

    I haven't used the TV enough yet to see it there, but I'm wondering if the somewhat "powered" HDMI connection on the monitor was contributing to that issue as well. I'll report back if I see any other details.

  • @caver01 Indeed it is a simple Methode to power off and power on the Pie. But as you said the power cutoff just be eine by a circuit called
    Mausberry PowerBlock AtxPie ....

  • @caver01 thanks for the reply must be my monitor than, because the dim light stays on if I unplug the micro usb power and leave the HDMI plugged in

    Im using a Asus MG28UQ

  • @drake999 said in NesPi Case Power Problems:

    Well I've suffered for the community yet again and through testing several adapters I found a working solution. I purchased the adapter below and no under-voltage issues whatsoever, with a 1350 Mhz overclock and the 5V fan attached to the NesPi case fan pins. I tortured all four cores for 30 minutes with sysbench and not one under-voltage warning. Temps remained below 65 degrees (because of my heatsinks and fan). For those who are interested, here is the adapter I used.

    @drake999 Just wanted to upvote and thank you for this suggestion. I ordered this power supply and believe to have fixed my low voltage warning issue with the NESPi case as well. I've been using it for over a month. I was previously using a 5v CanaKit power adapter. Thanks for your research! I appreciated not having to solder new wires in there.

    I had also bought a second NESPi case about a few weeks after my first, and that one has NOT shown any low voltage warnings to my knowledge (also using CanaKit 5v PS). Thinking either some variance between different builds or perhaps an improvement on newer production.

  • Hey guys iv been playing with issue for a little bit and was thing how was the power getting to the pies motherboard and think its getting its power from the usb port and the 5v fan pins.
    This had me thinking a long time back I connected a usb powered hub to one and found that the pie stayed on even if I disconnected the power from the pies micro usb port, but the under voltage symbol work come on and the machine would start to run very slow.
    So what iv done is solder to wires from the nespi case power and reset switch circuit board( theres 3 pairs positive + and negative - wires coming on and off it)
    I used the middle + and - to run a wire to the pies board (had to solder wires to board) positive + PP2 and negative - PP5 points on the underside of the motherboard near the micro usb port.
    This seems to have fixed the problem so I tested the pie by running 007 golden eye for the n64 (had the left dpad stuck down so the character would spin around over and over) for and hour and then tried Mario kart 64 (did the same thing with the buttons) for an hour then tried G-police 2 for the ps1 (same again with the buttons) for an hour I dident get under voltage fault.
    So I hope this will help im going to buy a few more nespi cases and try with them to se if it works with them too.
    Hope this helps

  • Did someone got it fix it the end right ?
    or just like that?
    alt text

  • @atexplosion

    I'm an electrical engineer, and I recently spent a day debugging all the boards and wires in my Nespi case because of the undervoltage alarm. I also tried multiple cables, power supplies, and other brands of cases, with and without fans. My conclusion ended up being that all of my USB cables were inferior, and I will explain why.

    For starters, Ohm's Law states that DC electric potential is equal to the product of current and resistance in a circuit (V = I*R).

    All conductors (wires) have an associated resistance (R, measured in ohms [Ω]). At low current (I, measured in amperes [A]), the effect of wire resistance is negligible. At higher current values, that effect becomes significant, causing a "voltage drop" (V, measured in volts [V]). A Raspberry Pi running Retropie has a pretty high current load compared to generic USB devices (like an optical mouse, or a game controller).

    For a given cross-sectional area, a copper wire has an intrinsic resistivity (that is, resistance per unit length, or Ω/m [ohms per meter]). Depending on the given USB cable, the power conductors typically range from 28 AWG to 24 AWG (0.08 to 0.25 square millimeters cross-sectional area), with the largest available (that I know of) being 19-AWG (0.653 square millimeters).

    The resistances of these three wire gauges at 10 ft are the following:
    28 AWG @ 10 ft -- 0.649 Ω
    24 AWG @ 10 ft -- 0.257 Ω
    19 AWG @ 10 ft -- 0.081 Ω

    Assuming an average current of 0.800 A (800 mA) for a medium-usage Raspberry Pi 3B+, using Ohm's Law, that would yield the following voltage drops:

    28 AWG @ 0.8 A, 10 ft -- 0.52 V
    24 AWG @ 0.8 A, 10 ft -- 0.21 V
    19 AWG @ 0.8 A, 10 ft -- 0.07 V

    For a 5-volt power supply, that would mean the voltage at your Raspberry Pi's micro USB connector would be the following:

    28 AWG @ 0.8 A, 10 ft -- 4.48 V
    24 AWG @ 0.8 A, 10 ft -- 4.79 V
    19 AWG @ 0.8 A, 10 ft -- 4.93 V

    The shorter your cable, the effects become lessened:

    28 AWG @ 0.8 A, 5 ft -- 4.74 V
    24 AWG @ 0.8 A, 5 ft -- 4.90 V
    19 AWG @ 0.8 A, 5 ft -- 4.97 V

    28 AWG @ 0.8 A, 2.5 ft -- 4.87 V
    24 AWG @ 0.8 A, 2.5 ft -- 4.95 V
    19 AWG @ 0.8 A, 2.5 ft -- 4.98 V

    Increasing the size of your power supply (higher current output) really won't get around these effects. Maybe going to a higher voltage would compensate for the drop, but your current changes constantly, causing the voltage drop to change constantly. You'd be risking damaging your Pi. The best solution is using the shortest standard cable available, or buying a cable with larger conductors if you need a longer length (the company Volutz offers the largest that I could find).

    The PCB boards in the Nespi case do slightly exacerbate the issue, but the biggest culprit is the main power cable. Once it's of sufficient length and/or gauge, the effects of the Nespi boards are negligible. I even had undervoltage faults using no case at all when I had a long power cable with thin wires.

    So, use a really short cable if you can, and you should have no issues, even using a Samsung phone charger.

    Than MacKenzie

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