MK4 Power Panic Issue - Can't boot
On the MK3, if you leave the power panic cable disconnected, no problem. On the MK4, if you leave it disconnected, the printer complains with a red screen that you need to check the power panic cable and there is no option to continue (just reboots to same error)
Is there a hidden firmware/USB drop file setting that will disable the power panic cable? - I do not want/ever need it as all my printers are powered by a pretty advanced 24V UPS system.
RE: MK4 Power Panic Issue - Can't boot
Try updating the firmware. I have mine powered from my own system with no power panic cable, and it boots and works just fine. I am on the Input Shaper alpha, but it worked with the other firmwares too.
RE: MK4 Power Panic Issue - Can't boot
Did it on the stock 4.7.2, tried 5.0.0-alpha3, and currently on 5.0.0-RC and it still does it.
Tried connecting just the black wire in the power panic cable to DC GND to fool it, but it still complains when power panic cable is not attached to the genuine Prusa (Delta) power supply.
Seems like the firmware logic should be, if power panic cable not detected, alert the user, but then allow printer to boot fully just with power panic 'feature' disabled.
RE: MK4 Power Panic Issue - Can't boot
I'd contact support... Mine is definitely running without that cable installed, in fact the power supply from Prusa is still sitting in a bag. Mine is on my sailboat and can be switched between my own 110vac/24vdc power supply, or directly to my DC breaker panel.
RE: MK4 Power Panic Issue - Can't boot
On ATX PSU the PG (Power Good) was a signal that went ground within 500ms, so making it ground instant would not fool large Intel and HP servers, they could tell something wasnt right with the PSU, i would guess Prusa are doing the same, and using a PSU thats abit better quality with regards the PG cable.
Many Thanks
RE: MK4 Power Panic Issue - Can't boot
I'm having this issue as well, having managed to first disconnect the cable from the board while putting it in the enclosure and then breaking a pin off when I tried to reconnect it. It's my fault, yes, but I am annoyed by both the design on the connection and length of the cable as well as the inability to bypass that warning.
RE: MK4 Power Panic Issue - Can't boot
I'm having this issue as well, having managed to first disconnect the cable from the board while putting it in the enclosure and then breaking a pin off when I tried to reconnect it. It's my fault, yes, but I am annoyed by both the design on the connection and length of the cable as well as the inability to bypass that warning.
I'm helping someone out with the same issue on Reddit. Is that you? We might get better traction here.
If you are getting Error 13321 on boot because your power panic wire is not connected, this is the section of code that is throwing it.
I have filed an Enhancement request...
https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/3255
Now... I need some help. I theorized that the xbuddy PCB lacks a pull-up resistor on the power panic line. Not having the power panic pulled up would mean that disconnecting the cable would cause a power panic fault. Can someone with a MK4 validate this by measuring the resistance between the power panic line and VCC and GND?
RE: MK4 Power Panic Issue - Can't boot
Everyone! Other users found a solution to this and posted it in my Github issue.
Conclusion: Disconnect the black wire from the power panic, while leaving the white wire connected to "V-" (or any other point tied to PSU negative) will disable power panic AND disable the cable check portion of the power panic.
RE: MK4 Power Panic Issue - Can't boot
Everyone! Other users found a solution to this and posted it in my Github issue.
Conclusion: Disconnect the black wire from the power panic, while leaving the white wire connected to "V-" (or any other point tied to PSU negative) will disable power panic AND disable the cable check portion of the power panic.
Thank you very much. I can confirm: works fine with my Meanwell PSU 🙂
RE: MK4 Power Panic Issue - Can't boot
The problem I'm having is that both the little pins on the board broke off and it was literally just a small box that slides onto the pins. A friend has been trying to solder directly onto the contact points with zero success as he can't get the solder to hold. Looking at the pictures in that github link makes me wonder if something pulled off the board that wasn't supposed to because I never had a small white box on the board when I opened mine up for the first time and found it disconnected. If that's the case then I'm about to try the solution mentioned by getting some new wire and trying to solder in a single line in the configuration mentioned.
RE: MK4 Power Panic Issue - Can't boot
If you absolutely need to, these are some of the pins you can short to GND to trick the power panic into thinking it is ok.
RE:
This is what I'm seeing on my board. Sorry, it's not a great picture. But I feel like it's not even the same one. 
RE: MK4 Power Panic Issue - Can't boot
Wow! I've never seen that board. Are you sure it's an xbuddy for a MK4? Can you take larger pictures of the rest of the board? There should be a version number on it as well.
RE: MK4 Power Panic Issue - Can't boot
Wow! I've never seen that board. Are you sure it's an xbuddy for a MK4? Can you take larger pictures of the rest of the board? There should be a version number on it as well.
Could you take a large one of yours please I see power panic written on jmshirly one but there is no port near by so I'm wondering if it's a faulty board
Please help me out by downloading a model it's free and easy but really helps me out https://www.printables.com/@Hello_474427/models
RE: MK4 Power Panic Issue - Can't boot
RE: MK4 Power Panic Issue - Can't boot
It's an xbuddy board. I see that on yours now. You are missing the white connector. However, you can see where it should have been. And while the white wire pin is ripped off your PCB, you can still solder a jumper wire to the resistor or cap I pointed out.
RE: MK4 Power Panic Issue - Can't boot
I tried this on my new just built XL to try an fix the power panic error an it did not work so its something else even flashing back an forward dont fix it alwasy red screen of death cant get past that do to this cable error I so believed in them an its dying now due too this! I got ripped on crap machine long ago once was even way less too but at least I got to print things for a bit with that machine this one will not let me even start it out to calibrate it.