5S / „There is a problem with the active level sensor“

[Torgeir 242]

This is a more close up pictures for sure, -but cannot be sure that there is an open wiring.

 

At this close distance from the heater core, the heat will extend along the wire and sometimes you burn the insulation at some distance from the sleeve. But with this much wear and tear on the fastening tab, it's strange if there is no hole in the wires insulation..

 

Another thing, if there is no short here, this short/close distance -mean higher capacitance.

So could this increased capacitance be the reason for (out of specification sensed) this error?

For sure, there is some options.

 

We'll se tomorrow.

Thanks

Torgeir

[jeffroe 3]

We have a "spare" print head PCB here from one that had a massive blob of material after a mechanical failure (head assembly replaced under warranty).  If i get time soon I will try swapping that out.

[jeffroe 3]

On 3/3/2021 at 7:44 PM, Torgeir said:

This is a more close up pictures for sure, -but cannot be sure that there is an open wiring.

 

At this close distance from the heater core, the heat will extend along the wire and sometimes you burn the insulation at some distance from the sleeve. But with this much wear and tear on the fastening tab, it's strange if there is no hole in the wires insulation..

 

Another thing, if there is no short here, this short/close distance -mean higher capacitance.

So could this increased capacitance be the reason for (out of specification sensed) this error?

For sure, there is some options.

 

We'll se tomorrow.

Thanks

Torgeir

Just finished making two changes...

 

- Added a bit of solder to the front of the connectors that hold the wires to the cap sensor board in the steel plate. There may have been a small crack in the solder, but I think it was just a shadow in my photos.

- Replaced the PCBA in the extruder head

 

It successfully passed the active level sensor test (no more low performance error), so I am now running the XY calibration print it has been unable to do since this issue started. After this print I am going to take another look at the wire on the print core I removed yesterday and try to get a better photo.

 

since I changed two things at once I can’t be 100% sure the PCBA in the back of the head was bad, but I think it is likely.

 

[Torgeir 242]

Hi Jeff,

 

great to hear that this printer is up running again.

Way to go.

 

Torgeir

[jeffroe 3]

1 hour ago, Torgeir said:

Hi Jeff,

 

great to hear that this printer is up running again.

Way to go.

 

Torgeir

Thanks - I took some pics of the wire under a cheap USB microscope.  Definitely a break in the insulation on one of the two wires.  I checked with a meter for continuity to the terminals on the back of the print core and the wire with the break was connected to the 2nd connector on the back of the core (viewed from the back).  I dind't check which pad this mapped to on the back - just the wire.  I would be curious to know if that is a +24V line or ground.

[Torgeir 242]

Hi Jeff,

 

I've been looking into the wiring diagram for this circuit and since this heater element is driven by a NMOS p-ch transistor,

both of this wires will be positive when no power is feed to the heat element. When the transistor is switched to on (for heating), the defined negative pin goes to ground. This will continue in a cycle pattern according to heat demand. I'll think ultimaker is using the "bang - bang" mode with a fixed frequency and timed on/off cycle (for reducing EMF noise).

 

Anyway, it looks like your "capacitive electronic chip" is most likely fried by the 24 VDC.  Max input here is +3.3VDC!

 

Way to go..  🙂

 

Thanks

Torgeir

 

[jeffroe 3]

1 hour ago, Torgeir said:

Hi Jeff,

 

I've been looking into the wiring diagram for this circuit and since this heater element is driven by a NMOS p-ch transistor,

both of this wires will be positive when no power is feed to the heat element. When the transistor is switched to on (for heating), the defined negative pin goes to ground. This will continue in a cycle pattern according to heat demand. I'll think ultimaker is using the "bang - bang" mode with a fixed frequency and timed on/off cycle (for reducing EMF noise).

 

Anyway, it looks like your "capacitive electronic chip" is most likely fried by the 24 VDC.  Max input here is +3.3VDC!

 

Way to go..  🙂

 

Thanks

Torgeir

 

Thanks for your help on this - much appreciated!

 

Which chip is this on the board?  Is it commonly available?  I would like to replace it on the board I pulled out if possible.

[Torgeir 242]

The chip for measuring the capacity is; U3 P/N: FDC1004DSCT.

The chip U8 (protection diodes) also has to be changed and P/N is; PUSB3FR4.

 

Thanks

Torgeir

[Whom 7]

I have been trouble shooting the same problem and found that the U8 chip has clearly let out the magic smoke on our machine. See attached photo.

 

I presume it was caused by the same issue, but haven't noticed worn through wiring on any of our core heaters. I'll check again. 

 

Seems like, from the inclusion of that little bit of heat shrink, this was a design error on the machine. 

 

 

[jeffroe 3]

13 hours ago, Whom said:

I have been trouble shooting the same problem and found that the U8 chip has clearly let out the magic smoke on our machine. See attached photo.

 

I presume it was caused by the same issue, but haven't noticed worn through wiring on any of our core heaters. I'll check again. 

 

Seems like, from the inclusion of that little bit of heat shrink, this was a design error on the machine. 

 

 

I ordered those protection diodes and the cap sense chip from Digikey back around the time I posted my saga with the intent of trying to replace those chips on the board I pulled out of that extruder. 

 

Unfortunately during the working from home and COVID situation, the shipment got lost in the building after it was delivered and I never bothered to order another set.

[Whom 7]

I did some more digging. The insulation on those wires is just a braid I think, so anything sharp can worm it's way into the metal. 

 

I also loaded the CAD and it is pretty obvious the tab lines up with the heater wires... 

 

I also found one of our cores has marks on the heater wire and the wire sticks down into that tab. 

 

Pretty disappointing on a 18 month old machine. I will make sure the wires on all our cores are bent away from the tab, and keep a vigilant eye on that tab insulation heat shrink, the jankiest of "fixes" I have seen on something this expensive. 

 

 

[jeffroe 3]

Yeah - I am pretty confident that is what happened in my case - that tab shorted against that heater wire.  I don't recall seeing obvious visible damage to either U3 or U8 on our board, but replacing the board with a spare solved it.

 

I wish we could have tracked down that digikey shipment to try to "save" that bad board, but been too busy to bother ordering more of them.  I think we probably still have the bad one in a box or drawer somewhere if I ever get motivated to try to desolder and replace the two components.

[Whom 7]

5 minutes ago, jeffroe said:

Yeah - I am pretty confident that is what happened in my case - that tab shorted against that heater wire.  I don't recall seeing obvious visible damage to either U3 or U8 on our board, but replacing the board with a spare solved it.

 

I wish we could have tracked down that digikey shipment to try to "save" that bad board, but been too busy to bother ordering more of them.  I think we probably still have the bad one in a box or drawer somewhere if I ever get motivated to try to desolder and replace the two components.

 

It really wasn't obvious until I got my macro lens out that U8 was blown. I was tracing the sensor pins around and stumbled upon a tiny darker area next to U8. If it is just a protection diode, I wonder if removing U8 and running without it might get us up and running until a new board arrives. I'm hoping Ultimaker foots the bill, this feels like a design issue to me. 

[jeffroe 3]

It definitely seems like a design issue - it's obviously why they put that little bit of heat shrink on only one of the tabs.  I would assume that without the protection diode chip the line would be broken if it was removed (if they are in series in the signal line).