Mainboard or power supply failure?

davedwin

I was cleaning my hot end with a brass wire brush (while on, and heated). The screen went blank during this, and now when I turn it on I get a single beep. I've tried; restart, reload firmware (via SD), connecting to PC, connecting to OctoPi, complete disassembly/reassembly, and turning on with nothing plugged into the board. I'm wondering if it could be the power supply because the fan on the power supply is not turning on, but if that was the case, wouldn't the main board not beep?

Stephen Todd

Disconnect the output of the power supply and see if the fan starts working when not connected to the printer control board

The power supply has short circuit protection, so should not have failed - maybe the fan only operates when there is a load on the output, and you've killed what was the load

You could put a load on the disconnected power suppy and see if it still outputs 24v - a mains voltage 60 watt old style filament light bulb is the usual test for power supply outputs

Stephen Todd

When my A3s V1 power supply self-destructed, I was able to test the printer was still working by hooking up a 65 watt laptop power brick - output was 18.5v, 3.5 amps - was powerful enough to control the motors, but not heat the hot end or bed

Samuel Pinches

Welcome @davedwin

Sorry to hear about your misfortune.
I agree that it's strange that you get a beep, but maybe that beep is hardware controlled and not software controlled. It's hard to know if your LCD is damaged or not too.

Laser8302

See my post. I've blown up 2 mainboards messing with the hot-end with the power on.

https://jgmakerforum.com/discussion/1052/always-disconnect-power-before-working-on-your-printer#latest

If the hotend fan turns on when you turn on the power and nothing else works, most likely the mainboard is broken. I'm putting in a PTC fuse to protect the thermistor input/ground circuit to prevent something like this.

Stephen Todd

Without your printer switched off, connect printer to turned on laptop/computer, using USB cable - you should get the "beep" and the LCD should light up and proceed to display the icons - at least that's what happens with A5/A3s V1 - should be same with the new all-in-one board

The USB will not have enough power to operate the motors or heaters, but otherwise the LCD should be functional - if not then I'd say the controller board is dead

Edit: corrected typo - printer should not be powered on - you want to see if USB power enables operation of LCD without the printer PSU

Samuel Pinches

May be worth trying to connect to a computer, and then try to connect via Pronterface?