Flux Capacitor Not Fluxing

Ok electronic Wiz Kids - I have a Shapoko 3XXL (not that size matters :wink: ) with Carbide Motion board v2.4e. One of the capacitors (I think, see pictures) has a broken pin which I think is the cause of the Z probe not working. The pin is sheared off a few thou below the bottom of the unit. No apparent heat damage, just vibration would be my guess.

I’m good enough with soldering to R&R the part, but not sure what to order. I’ve tried to look up the part number for the capacitor with the arrow and it is 7923TQ 1000uF 50V. The capacitor beside it is 7803TQ, not that that matters either.
There are a lot of of hits that come back from Mouser, Digi-Key etc. for about $1, but I’d like to get the correct one one the first try.

Optionally, I could get a new board, should I?


I guess it depends on how comfortable you are with doing soldering rework. Me I would in a heart beat. The cost of a cap is negligible and should only take a few minutes to do.

IMHO, not worth the cost of a new board.

Agreed, but thought I’d ask about the board replacement anyway. Still need to confirm the replacement part before ordering.
I should also ad that the diameter of the current part is 13mm, height 25mm and the pin spacing looks like 5mm.

Is it still under warranty?

I don’t think so as it’s 5 years old, and performed awesomely I might ad!


Seems like you have all the information that you need. Be prepared for the cost of $1 to bloom up with shipping. If you’re in Texas, then use Mouser, but it doesn’t really matter. You might even find one on Amazon or eBay.

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Amazon has 10 pcs for $8 with free shipping and easy returns if they don’t turn out to be correct. No pin spacing listed, I’ve asked, but no answer.
Prefer Mouser as I’ve dealt with them a lot in the past, but you are correct about their shipping costs, sigh.

And yet I wonder if the cap has anything to do with the probe input failing?
I seem to remember the giant caps in early 2.4 boards had something to do with EMI filtering.
The probe input can’t be triggered anymore?


That’s correct Julian. The z crashed the upper limit when I started the machine this morning. So I went to the Settings screen and tested each probe, x and y are fine but no firing of z. So I traced the wiring back looking for breaks or shorts and got to the control board and saw the loose capacitor. There is no other damage on the board that I’m able to find, so I’m hoping it’s just a capacitor.
I don’t see boards in the accessories page on carbide3d.com, those would be available via support if I"m unable to get this worked out?

There is (used to be?) a private link to order the controller, but they may not be in stock, support should be able to tell you about the availability.

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Yes, they are on a hidden page in the shop (check the BitRunner page for a link) — support@carbide3d.com will have details.

Just a thought: I used to have the same controller, and the Z limit switch signal happens to also be available on one of the unused connectors (see #17 in the ebook Section about the controller). You may want to try shorting that Z pin there to GND, see if it triggers? Just in case the problem lies somewhere in the circuit from the regular switch connector


Counting from the top left of block 17, I should plug the z limit switch into pins 3-4 or 4-5, correct?
Only asking because I know you’ve got that voltaic VooDoo and I, well, don"t.

For fun I tried swapping the Z onto the Y and guess what, it’s the switch, D’OH! fortunately, I have a proximity switch kit!
I’ll still get the replacement Cap, to continue to avoid those EMI issues. Thanks @Julien for kicking my synapses into gear!

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I can not understand why EMI filtering would ever need such a large cap. However, it would be normal on a power supply line for filtering DC fluctuations. So, definitely fix it before using your Shapeoko again.


Large caps are there to keep the DC voltage stable when the motor drivers pull sudden bursts of current.
EMI filtering usually involves small caps that provide a low impedence path for high frequency noise to ground.

So you definitely want to replace that cap! Without it, there could be a chance that when all motor drivers suddenly pull max current simultaneously, the controller board goes through a power reset due to a loss of appropriate input voltage.



I suppose it’s a matter of interpretation of what falls under the term “EMI”, there are tiny gremlins that generates glitches in the tens of microvolts (small caps to the rescue), and there are large power surges (router starting…) that could temporarily alter the controller’s operating voltage (large caps/ energy reserve to the rescue).
I’m a simple man, I observe that those large caps were later removed from the design, while all the rest of the design remained mostly unchanged (before the latest 3.0 controllers that is), so I still have a hunch that the controller would work just fine with only one giant cap left. I’m not saying it should not be fixed, I’m saying I’ve been in the position to have to solder things on the controller, and it felt like russian roulette. One slip of the soldering iron or a tiny bit of solder in the wrong place, and one can fry the board (for good this time). I’m sure @MikeG will pull it off though :slight_smile:


The replacement capacitor will be here Tuesday, looks like the correct unit :crossed_fingers:
Thanks for up vote @Julien! I managed to remove the old unit just fine, despite not have a working CNC to mill the old solder out :wink: This board is very robust and the pins on the backside are well away from and isolated from any others, thusly no problem with a tiny iron in the area.
It’s all about DIY for me, and fixing what can be fixed instead of replacing whenever possible.
Thanks all for the mini lesson in capacitors!

And, just FYI, I’ve never had a disconnect in all the years, and we get our share of dry hot weather here. I do run the CM computer and controller on a seperate circuit with a battery backup and EMI suppresssion from the router and the dust collection is on another seperate circuit. So a total of three seperate power sources.


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