Error 73 and “Exception in Hotend_fan”

Sovol Zero
1

After using some different macros and going back to the stock ones, my printer is continually crashing with either Error 73 or “Exception in Hotend_fan”. I’ve factory reset it after getting this error repeatedly and it cannot get past the calibration stage without crashing.

Help in how to solve this issue is greatly appreciated.

2

Have you tried to flash the last firmware?

3

I am on the most recent firmware according to the screen:

1.4.7

2025-5-20

4

Yes but who knows? A corrupt firmware?

5

I asked it to install again but it says I am on the latest. Is there a way to force an update? I am well-experienced in Linux and doing stuff via the command line.

6

I don’t own zero but have you tried to force it with adapter?

7

I have not done that but having mainlined my SV08 I could try that.

8

@Lion could you help him?

I don’t want to make a fatal mistake.

9

I’m not exactly sure about the error…have you had a clog or removed the toolhead lately..??
It’s possible that a loose plug on the toolhead board is causing your issues.

It’s also possible that your reset didn’t clean out your macros, do you have a backup file from before you made the changes..??

@Liberty4Ever
@cardoc

10

No clog recently but I cannot heat up the hot end to unload filament now due to it crashing if I try and heat it up.

I kept all my old macro files and went back to what I was using before

11

Check the wires/plugs like I suggested..if that doesn’t fix it..my only guess would be a macro issue.

12

I don’t have a Zero so I’m unable to verify this…

The version of printer.cfg on github contains the following:

[heater_fan hotend_fan]      
pin: extruder_mcu:PA6   
max_power: 1.0      
cycle_time: 0.015         
kick_start_time: 0.5         
heater: extruder             
heater_temp: 45              
tachometer_pin: extruder_mcu:PA1
tachometer_ppr: 1
tachometer_poll_interval: 0.0013

None of my printers have tach feedback on the hotend fan but I assume that the fan is not spinning up OR the tach signal isn’t valid. Check the plugs at the toolhead board.

One diagnostic technique would be to comment out the 3 tachometer lines. Should allow normal operation but the operator is responsible for verifying the fan is working.

13

I posted something similar in the ACE forum, but wasn’t sure it was relevant or not.
But you thought the same, so I will post it now.

14

Commenting out the tachometer section in my printer.cfg appears to have made it functional again but I worry about run-on effects from doing that…

1 Like
15

I did the following after modifying my printer.cfg:

  • did a PID tuning
  • did resonance testing
  • doublechecked the values in my printer.cfg with what is up on Github for the Zero
  • did a power cycle

I then tried heating up the extruder and it heated up to 250C with no problems and no crashes. I am not sure what caused the issue but so far it appears to be working okay.

I appreciate everyone’s help.