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Continuous alarm beep during preheat.  

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brentonator
(@brentonator)
Active Member
Continuous alarm beep during preheat.

I have a MK3 and it recently started to give a continuous loud high pitched beep when I preheat or print anything. The temperature for both the bed and hot end report normally and I don't get any errors on the LCD. I can complete prints with no problem. The beep starts as soon as the bed and hotend start heating up. Once the bed and hotend are at the set temperature the beeping will become sporadic and seems to be related to when heating is actually happening.   In other words as the heat is regulated by turning the heater on and off, the beeping will turn on and off accordingly. As soon as the print is over or I set preheat to cool down the beeping stops. I'm not able to tell if it is the bed or the hot end that or both that are causing this alarm. 

I can continue to print for now, but that beep is super annoying and I would like to address whatever is causing the issue . 

After not using my printer for a weeks, I updated the firmware to 3.9.3 and that is when this first started happening.  I have tried all the older major version of the firmware all the way back to 3.2.1 and none of the older firmware versions fixed the problem. I think the firmware upgrade was coincident with the onset of the problem, but did not actually cause the problem. I wanted to mention that I had done this it just in case. 

I also tried unplugging and reattaching the cables for the thermistors. I would expect if it was a loose or faulty connection that I would see erratic temperature readings especially during printing when the cables are moving around, but the temp reading are stable and seem to be reporting correctly. 

At this point I'm out of my depth and am really hoping someone can help me figure out what is going wrong. I have moved my printer into another room where I can close the door just to try to be able to continue printing without going crazy. Please help me save my sanity. 

Best Answer by brentonator:

Well after compiling my own version of the firmware with all sound disabled, I was still getting the beeping during heating. I was really bummed out, but then I had a stroke of luck. I moved the printer to another room with better light so I could start testing with a multimeter. When I plugged it back in the problem no longer happened!! Then I remembered that I had added APC UPS in the room with the printer. Sure enough, when I connected the printer back to the battery back up outlet on the UPS the problem returned. The surge protected outlet on the UPS doesn't have the same problem so I switched to that plug and am happily printing in silence again. 

This topic was modified 9 months ago by brentonator
Posted : 30/01/2021 5:12 am
brentonator
(@brentonator)
Active Member
Topic starter answered:
RE: Continuous alarm beep during preheat.

I went into the temperature menu and by playing around with the nozzle and bed temp settings independently, I figure out the beeping is related to the bed heating up and not the nozzle.  I have also downloaded the source code for the latest firmware and am looking at `Prusa-Firmware-3.9.3\Firmware\temperature.cpp` to see if I can figure out what is going on.

Posted : 30/01/2021 7:48 pm
brentonator
(@brentonator)
Active Member
Topic starter answered:
RE: Continuous alarm beep during preheat.

The only bits of code I can see in `temperature.cpp` that are calling a sound API are

void temp_runaway_stop(bool isPreheat, bool isBed)
static void fanSpeedErrorBeep(const char *serialMsg, const char *lcdMsg)
Since I'm able to print successfully, it can't be temp_runaway_stop because that stops everything and clears the command queue.
That leaves fanSpeedErrorBeep. A few things about that confuse me:
- that code should also print a message to the LCD which isn't happening in my case.
- when I do a calibration, the fan tests pass.
- I only get the beeping when the bed is heating and there are no fans on the bed. 
I guess it is time to expand the search to the rest of the source code. :-/  
Posted : 30/01/2021 8:10 pm
brentonator
(@brentonator)
Active Member
Topic starter answered:
RE: Continuous alarm beep during preheat.

Well after compiling my own version of the firmware with all sound disabled, I was still getting the beeping during heating. I was really bummed out, but then I had a stroke of luck. I moved the printer to another room with better light so I could start testing with a multimeter. When I plugged it back in the problem no longer happened!! Then I remembered that I had added APC UPS in the room with the printer. Sure enough, when I connected the printer back to the battery back up outlet on the UPS the problem returned. The surge protected outlet on the UPS doesn't have the same problem so I switched to that plug and am happily printing in silence again. 

Posted : 31/01/2021 4:34 am
brentonator
(@brentonator)
Active Member
Topic starter answered:
RE: Continuous alarm beep during preheat.

Well after compiling my own version of the firmware with all sound disabled, I was still getting the beeping during heating. I was really bummed out, but then I had a stroke of luck. I moved the printer to another room with better light so I could start testing with a multimeter. When I plugged it back in the problem no longer happened!! Then I remembered that I had added APC UPS in the room with the printer. Sure enough, when I connected the printer back to the battery back up outlet on the UPS the problem returned. The surge protected outlet on the UPS doesn't have the same problem so I switched to that plug and am happily printing in silence again. 

Posted : 31/01/2021 4:34 am
Dan Simms liked
Dan Simms
(@dan-simms)
New Member
RE: Continuous alarm beep during preheat.

Huh. This was the first result when I searched, and sure enough, I had plugged my printer into an APC UPS as additional protection for a 2+ day print.

Once I'm done with it, I'll just switch back to the wall outlet. Thanks!

Posted : 16/09/2021 12:50 am
Swiss_Cheese
(@swiss_cheese)
Noble Member

I use pure sine, for this very reason steped sine will not cut the mustered.

 

Good Luck

 

Swiss_Cheese

The Filament Whisperer...
Posted : 16/09/2021 1:55 am
jsw
 jsw
(@jsw)
Noble Member

Just another data point here.

I have the MK3S/MMU2s, mostly stock, running on a Cyber Power Best Buy Special UPS for the printer alone.

I have no clue whether it's square wave or stepped quasi-sine, but a few weeks ago we had a power failure during a multi-hour print and the UPS took over.

We have a backup generator, but it's not auto-start and it's manual transfer.  The battery on it was dead (since replaced) so I had to use a jump box to get it going, so it was a good 20 minutes from lights out to lights on and the printer was on the battery in the UPS for that 20 minute period.

No issues at all with the print.  In particular, there were no beeps at all from the printer.  I'm sure that a few cycles were lost when it transitioned from 'shore' power to (square/stepped) battery power and back to (sine) generator power.

IIRC, the MK3S has enough DC reserve so that if the power goes out it has enough to save the state and to raise the print head before the DC totally drops out.  I don't know if the MK3 (no-S) has this as well.  In any case, mine went through two power transitions with no issues at all.

Posted : 16/09/2021 2:25 am
Swiss_Cheese
(@swiss_cheese)
Noble Member

well, if it makes a difference the printer I'm referring to is MK3 not s

The Filament Whisperer...
Posted : 16/09/2021 2:38 am
Dan Simms
(@dan-simms)
New Member

I'm using an APC Back-UPS 600, which does use a step-approximated sine wave. I will have to upgrade at some point to a pure sine wave UPS at some point. Thanks!

Posted : 16/09/2021 3:12 am
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