No fans on either main board or Duex
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@sinned6915 said in No fans on either main board or Duex:
or configs that are not right.. i am still struggling with the RRF3 stiff
Config, nor mosfets will have
andany effect on always on pins, they're hardwired to Vfan and ground -
So after closer inspection, there was charring on the face of one of the fan molex connectors. I decided to pull it and see what was going on. The bottom of the connector was melted.
There is a crater there. The back side of the board is ok. I have no idea how 'deep the damage is, but am assuming that what I see 'up' may also be 'down'
When I look at the KiCAD for the rev 1.02 board, these are the copper layers, and I have tried to mark out where the crater is.
Top Layer of copper + silk-
Top layer & Middle layer + silk -
Top Middle layer & Bottom copper
Bottom Middle layer-
So now I am trying to figure out how I might further diagnose and repair this.
Frankly, I have never attempted something like this before. I have soldered kits and the like together, but nothing like this.
The bottom middle layer- I can not tell what does- is it a ground plane? Can someone clarify what it is and its purpose?
What else should I check for damage?
Can I jumper the V_FAN on the back side to skip the current carrying capacity in this area?
Similrly, can I jumper the V_IN to bypass the trace on the middle layer that might be damaged?
Why would this affect the fans on the Duex board? Or perhaps I am not assinging the fans on that one correctly and they are in fact ok?
thanks in advance
Dennis
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a couple more images that might be helpful-
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wow..
fixing it relatively simple as you can solder a wire from vin screw terminal to vin on the vfan selection jumper on the back side of the board.
and/or
solder wires from the vfan pin on the fan headers to the vfan selection jumper as needed.
if you can i'd use an in-line fuse as you've clearly had significant current going somewhere it shouldn't.
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To be clear, I received this board second hand, I did not make this carnage.
@bearer should I try to clean out the crater? Are the remnants of the crater conductive?
I was trying to find 1A fuses to makethe similar protection as the newer boards.
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Yeah, you'd want to clean it as best you can, using a fiberglass brush, or something like tha,t to remove the loose burned bits to prevent them from coming loose causing issues elsewhere.
Oh, and yeah, bottom middle (pink) layer is a ground plane - you can see the thermal relief connecting to the ground pins.
As for the Duex, I can't see how that failure should affect the Duex (besides dragging Vin down but then the duet should have complained about vin?), anyways you'd want to see if you can find other signs of where all that current has been causing potential havoc (but it could also be caused by heat as a result of contact resistance, but would expect the plug and terminal to look worse than the board in that case)
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I borrowed the neighbor kid's USB microscope-
i am kind of impressed by how well it took the picture.
EDIT: here is the schematic with a circle over the damaged area. PEr dc42's description below, the trace that is in the middle layer that crosses the circle is the one that fails. I rotated the snip of the KiCAD PCB image to match the close up photo of the damage.
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@bearer said in No fans on either main board or Duex:
wow..
fixing it relatively simple as you can solder a wire from vin screw terminal to vin on the vfan selection jumper on the back side of the board.
and/or
solder wires from the vfan pin on the fan headers to the vfan selection jumper as needed.
if you can i'd use an in-line fuse as you've clearly had significant current going somewhere it shouldn't.
This has come up several times before on the forum, for example https://forum.duet3d.com/topic/1062/duet-wifi-always-on-fan-connector-short. On 1.02 and earlier boards, the VIN feed to the fan voltage selector block passes through a via in the PCB, and that via fuses if there is a short circuit. The fix is indeed to add the wire as you suggest.
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thank you dc42. I see how my searches did not turn this up as a result.
i will report back with my sucess hopefully in a few days
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@dc42 @bearer can you help with deciding on a fuse retrofit?
i was looking at both blade and catridge holder, there is not much room to do it on or near the board. then i thought about in line components like this one-
I am imagining either using that inline fuse as either my wiring jumper or by making a little wiring harness to put between the fan and the pins once i make a jumper on the board.
what are your thoughts or reactions?
thanks
Dennis
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Unless you've identified why the board took the blow I'd go for an in-line fuse holder, either automotive or 5*20 glass fuse.
Newer boards use 1A, but almost anything below 2A should be fine. 100-200mA per fan should be ok methinks, or you can look at the fans in question
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The previous owner of this board attempted to connect a buck converter to backfeed 12V to the fan system instead of 24V main voltage or 5V onboard voltage.
I belive that he reveresed the polarity while attempting to connect everything. -
@sinned6915 said in No fans on either main board or Duex:
reveresed the polarity
Go figure. That usual works.