Sparks while changing hotend nozzle - Is my board fried?  

RE:

Your description seems to imply the power supply and microprocessors are probably OK. 

I would check:

Board fuses.

Voltage on the heater at the board terminals.

Disconnect on side of the heater circuit (power off) and check the heater resistance. Check that the exposed bit of wires at the extruder are intact.

Check the thermistor readings if available on the display with a hair dryer to see temperature change. If not available on display check for changing resistance.

Then I would suspect a blown component of the board. diagram is available to locate the driving heater FETs and see if they are damaged.

Good luck with it.

RE: Sparks while changing hotend nozzle - Is my board fried?

I agree with your diagnostic and advices. If the wires of the heater shorted and now the printer refuses to heat the nozzle, in all likelihood either one of the fuses or the FET controlling the hotend heater is damaged. Question is if the fuse was fried in time to save the FET or not. Maybe the FET died before and the fuse is OK.

Of course replacing a plug-in fuse is way easier than removing and soldering a FET on the Einsy board. Although Prusa doesn’t sells spare fuses they aren’t difficult to find online.

RE: Sparks while changing hotend nozzle - Is my board fried?

@Artur5

Like the old adage in audio power amps:

The $50 MOSFET gave its life promptly to save the 50¢ fuse..... 

RE: Sparks while changing hotend nozzle - Is my board fried?

Posted by: @richnormand

@Artur5

Like the old adage in audio power amps:

The $50 MOSFET gave its life promptly to save the 50¢ fuse..... 

Huh.  That’s why you need a tube amp...  an even older adage.

RE:

I have the exact same problem as described above. So far…

• Board fuses.
  • Ok here.
• Voltage on the heater at the board terminals.
  • Not done yet
• Disconnect on side of the heater circuit (power off) and check the heater resistance.
  • Not done yet
• Check that the exposed bit of wires at the extruder are intact.
  • Ok here.
• Check the thermistor readings if available on the display with a hair dryer to see temperature change. If not available on display check for changing resistance.
  • Not done yet
• Then I would suspect a blown component of the board. diagram is available to locate the driving heater FETs and see if they are damaged.
  • Where can I find the diagram, and what’s a FET?

I just found this post and is late now, so I will work on these recommendations tomorrow.

I will say that I ran a self test and everything works fine, fans, axes, bed, but when it starts the “hot end” test, the system quits the test and it goes back to the main information screen. The test never fails but it never really does the hot end test either.

RE: Sparks while changing hotend nozzle - Is my board fried?

Update.

I managed to sort this out few weeks ago. Basically there was an issue with the heater wire closer to the hotend. The spark occured because of the contact between the two wires, which melted the dried up filament around it, locking the two wires together. I confirmed this by measuring the resistance across the heater wires (where it's plugged into the motherboard) and it was either very high or very low (can't remember), but the normal value is around 10-20 ohms. 

I also measured the resistance across the hotend fuse which was 0.

The solution was to repair the hotend wire and reinstall the insulating cable. This worked in the end, and everything went back to normal after the reinstallation.

To prevent this problem from happening again, I ditched the E3D V6 lol. I now use a E3D Revo and it's amazing. Very easy to use and safe. Those things matter much more to me than being open source.

Hope this helps someone.

RE: Sparks while changing hotend nozzle - Is my board fried?

Are you saying the two wires going in the hot end, the white big ones with red sleeves, are not supposed to be touching each other in the block? Because mine are clearly touching and I don't see a why how to isolate them. 

RE:

Don't move those wires around/bend them. They are isolated, don't worry. This is how it's supposed to look (pic from assembly instructions):

Posted by: @samuel-2

Are you saying the two wires going in the hot end, the white big ones with red sleeves, are not supposed to be touching each other in the block? Because mine are clearly touching and I don't see a why how to isolate them. 

 

RE: Sparks while changing hotend nozzle - Is my board fried?

Hard to say for sure but it looks like Samuel’s heater wires may be touching, causing a dead short. The white insulation looks to be scorched as well.

I would start by disconnecting the heater plug from the Einsy board and measuring the resistance of the heater.

RE: Sparks while changing hotend nozzle - Is my board fried?

Wires were definitely touching each other, I was able to separate them and I read the ohms, and it reads 0.2 to 0.3 ohms. 

RE: Sparks while changing hotend nozzle - Is my board fried?

Correction, 1.5 ohms

RE: Sparks while changing hotend nozzle - Is my board fried?

Update:

• Board fuses.
  • Ok here.
• Voltage on the heater at the board terminals.
  • I set it to preheat for PLA while measuring, and I read 23.7 volts. 
• Disconnect on side of the heater circuit (power off) and check the heater resistance.
  • 1.5 ohms
• Check that the exposed bit of wires at the extruder are intact.
  • They are not ok, they appear to be touching each other. I've attempted to separate them, but the area there is very small. 
• Check the thermistor readings if available on the display with a hair dryer to see temperature change. If not available on display, check for changing resistance.
  • I used a hair dryer and I see temperatures change. I think they are real temperatures. 
• Then I would suspect a blown component of the board. Diagram is available to locate the driving heater FETs and see if they are damaged.
  • Where can I find the diagram, and what’s a FET?

In order for me to measure the voltage at the board, I had to disconnect the hot end cables and connect the multimeter. Before doing this, I was not able to "preheat" without the system crashing. I mean, if the hot end cables are connected, I can't preheat the hot end because the system restarts and goes to the main info screen without actually starting the preheat process. This tells me that my hot end isn't working anymore. 

Thoughts?? 

RE: Sparks while changing hotend nozzle - Is my board fried?

Einsy board schematics:

https://github.com/ultimachine/Einsy-Rambo/blob/1.1a/board/Project%20Outputs/Schematic%20Prints_Einsy%20Rambo_1.1a.PDF

There could be some versions differences over the years but it will give you a good idea of the layout..

From your comments, it look like the board is OK when the heater is not connected. The 1.5 ohms looks like the residual resistance of the connecting wires assuming it is a dead short at the heating capsule. About 24V from the board is appropriate I think. I would be tempted to remove the heating capsule (careful of the thermistor) from the hot end for closer examination or just order an appropriate replacement as they are inexpensive. I keep a thermistor and a heater as spares here.

RE: Sparks while changing hotend nozzle - Is my board fried?

+1 - What @richnormand said. I would order a replacement heater cartridge (and a thermistor as a backup).

Cheers

From your comments, it look like the board is OK when the heater is not connected. The 1.5 ohms looks like the residual resistance of the connecting wires assuming it is a dead short at the heating capsule. About 24V from the board is appropriate I think. I would be tempted to remove the heating capsule (careful of the thermistor) from the hot end for closer examination or just order an appropriate replacement as they are inexpensive. I keep a thermistor and a heater as spares here.

RE: Sparks while changing hotend nozzle - Is my board fried?

I’ve order the replacement. I will update after it arrives. Thank you for your help.

RE: Sparks while changing hotend nozzle - Is my board fried?

I'm happy to inform that it was the heater. I went ahead and upgraded to Rapid Change Revo Six from E3D. The reason I got into all this trouble is because I was trying to change the nozzle. So with this new upgrade I should be able to avoid repeating the same mistake. 

By the way, while researching this problem, I found that other people experience similar problems while cleaning the nozzle with the copper (or other metal) brushes. 

Thank you all for the awesome help y'all provided. 

RE: Sparks while changing hotend nozzle - Is my board fried?

Hi Samuel - Glad you got it sorted and that no damage to the Einsy board occurred.

Enjoy your printer!

Cheers

RE: Sparks while changing hotend nozzle - Is my board fried?

Thank you for posting this.  I just had this issue after tightening my hotend. 

I saw a spark because the heater cartridge wires touched as I was cleaning and tightening.  I turned the machine off and separated the wires.  After that, the machine was still resetting when I attempted to heat the nozzle.

My issue wasn't that the two wires were touching as shown in the photo above but rather one wire was bent down and touching the actual heater cartridge.    I pushed the wire up so it wasn't touching any metal and that fixed the issue.  In short, the wires shouldn't touch each other nor should they touch any other metal.

All the wire touching/moving was done with the power off.