microSD extender cable issues?

I’m running an Ender 3, and the microSD slot is difficult to get at; I keep dropping the card or struggling to get it aligned with the slot. I decided to try one of those microSD extender cables, just a straight-through pin-to-pin male microSD to female microSD flat ribbon cable setup.

I never ‘hot swap’ the SD card as this is a practice that carries risks. I insert the card, then turn on the printer. Never had any issues.

So I plugged in the cable male end, inserted the SD card in the female end, then turned on the printer. It sees the card, reads all the files, and accepts the print command. What happens is that after the bed and nozzle reach printing temp, the machine moves the nozzle to 0-0-0, then runs to the back of the bed and then brings it back forward, laying down a short run of filament (I’m assuming this is a nozzle purge or prime) as it goes… but it stops halfway to the front and reboots to the splash screen followed by the information screen. No way to resume the print, as no print is active now.

Tried this several times with the same file with the same result. Switched machine off and back on, it read the card, and I tried printing a different file. Same exact result. Another power-cycle reboot, then tried printing a “known good” file that printed successfully a few days prior, and once again, got the same reboot halfway through the pre-print nozzle purge.

Finally gave up and pulled the cable and plugged the card back into the semi-accessible card slot, and it prints fine, no issues whatever.

Is this a problem endemic to these extension cables, or some quirk of the Ender firmware that maybe a firmware upgrade (or switch to a different firmware like Klipper or Octoprint) might solve? Anyone else experiencing similar issues with extender cables?

Any advice or thoughts are much appreciated!

sounds to me like you got a bad extension, If you can use the same file directly and it works problem should be in the cable. Unfortunately cannot test that one unless you or a friend of yours has a similar printer you can try your cable on his printer?

These extenders, which are a great idea and may save your mother board, are cheap and of dubious quality. You probably got a bad one.

Thanks… that was my initial take. They bang these things out by the tens of thousands, and if they do QC sampling on 2% of them I’d be surprised. I did see a number of people complaining about having issues with them, and often switching firmware (Marlin to Klipper, for example, or Octoprint) seemed to clear up the issue. I’ll try another one or two before I give up on it.

I use an extender on a kingroon kp3, and it works just fine. I practically always hot swap cards on my enders though, but obviously not while printing, and have never had it cause an issue over 3 years on two ender 3s. Maybe I’m lucky, but I would find extremely annoying to power off the printer to remove the card if it is not reading or writing to it. Just my thoughts.


I’m not preaching or anything… I used to work with electronics quite a lot, and I’ve been bitten by both the ‘static bug’ and ‘hot-swap’ bugs often enough that I just don’t do it anymore. Bad enough when someone else is footing the bill! It can damage memory devices and electronics in general if they’re poorly protected. Had my fill of both. Your mileage may vary.

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Is is possible that you’ve misaligned your cable when you insert it, like upside down?

Hi Jay…

I won’t say it’s impossible, but it’s highly unlikely, as it won’t insert at all if it isn’t oriented correctly (not without a lot of force, anyway.) I was also careful to check the orientation before plugging it in. I did note that the cable did NOT lock into place like the card itself does. Made sure that this wasn’t the issue as well.

Those extension cables are not very good quality. I bought one almost 2 years ago and it didn’t work well so I put it aside. I saw several comments on the web about these. It’s seem to be hit and miss, you could get one that works, or not.

If you’re looking for quality premade cables, check out https://digikey.ca (or digikey.com if you’re anywhere else) and search for “Rectangular Cable Assemblies”.

They have a wide selection of premade cables with ones that should meet your needs in terms of connectors and cable length.

Not the cheapest option, but they’ll get the cables to you in 24 hours and they will be of good quality.

Hi Folks,

Replies are all appreciated! I’m on attempt #3 to pick up a cable from the 'zon, and so far none have worked. “Media failed to initialize” in cable socket, works fine with no cable. I’ve also learned that my machine (Ender 3) does not support 32 Gb cards, so that’s a likely part of this mix as well; have an 8 Gb SanDisk card on the way, so we’ll see if that makes any difference. I’ll post the results back here.

Thanks again!