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geekhack Community => Keyboards => Topic started by: KarmaUL on Sat, 09 September 2017, 07:33:12
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Hi there.
Some time ago I bought a non-backlit version of the Magicforce 68.
Now I wanted to exchange the USB cable that came with it but the replacement standard mini-USB cable doesn't work =(
I never thought of USB cables - so far I bought them, pluged them into the KB and they worked... Not so this time.
I recognized in contrast to the standard mini-USB plug, the one that came with the Magicforce has 6 pins instead of 5 as normal.
Any idea why? I can't imagine what an additional pin should do in a USB cable..
So, standard cables don't work with it obviously. I've seen other magicforces with replacement cables and never read anything about problems here..
I solved it by building a new cable using the (cut off) plug of the cable that came with the KB - but that's definitely not the way its meant to be, right?
Any idea what I've been doing wrong?
Thanks and best
K
a.k.a USB noob
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My Magicforce 68 has a normal mini usb cable. 5 pins. (Got it from Amazon Germany, Gat. Brown Backlit version) Never heard of any other types of mini usb cable. Shouldn't the plug be standardized?
Normally the only thing one should keep in mind with cables for a MF 68 is wire diameter for it to fit in the cable rail. Some braided cables could be too thick.
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I just received a non-backlit Magicforce 68 with outemu blues from Amazon today. I tried a different usb cable from the one bundled with the keyboard to see if it had the same issue. That generic usb cable was able to work with the keyboard without any problems.
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Obviously there are different revisions of this KB..
And I found others having the same problem (but only on the non-backlit version):
https://www.reddit.com/r/MechanicalKeyboards/comments/55dyrs/pexon_usb_cable_not_working_with_new_magicforce/
I cut off the original cable to have a look and it turned out that MF used a 5 core cable for whatever reason.. The 5th one is a bare cable - but seems to be critical for getting it to work..
(Whilse all my custom cables use 4)
So, probably the 5th core also just runs on mass - but who knows. My KB works ONLY with the stock cable it came with..
So, maybe I should solder a new standard mini-USB socket to the board to make it work with standard cables?
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... keep in mind with cables for a MF 68 is wire diameter for it to fit in the cable rail. Some braided cables could be too thick.
Right - but I stripped off the entire shrink tubing - still nothing.
Also my neat pexon cable doesn't work which is definitely fine :(
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Obviously there are different revisions of this KB..
hmm, I wonder when this revision took place. The qc date code on the keyboard I received is from 04/17 and its serial number begins with IF21703XXXXX.
I cut off the original cable to have a look and it turned out that MF used a 5 core cable for whatever reason.. The 5th one is a bare cable - but seems to be critical for getting it to work..
(Whilse all my custom cables use 4)
So, probably the 5th core also just runs on mass - but who knows. My KB works ONLY with the stock cable it came with..
So, maybe I should solder a new standard mini-USB socket to the board to make it work with standard cables?
I'm curious about this issue myself so I did a bit of research. That additional wire that you encountered in the cable is the shielding ground wire. It connects the outside shell of the USB receptacle or plug to the grounding foil within the USB cable.
(https://i.imgur.com/XY4QikX.gif)
I don't think the issue is with the mini-USB receptacle but rather how the cables you have are wired. There's a small daughterboard on the Magicforce that connects the USB receptacle to the main PCB. It's a bit tough to see but I believe there's five wires going from the daughterboard to the main PCB:
(https://i.imgur.com/Pzu1CObl.jpg) (https://i.imgur.com/Pzu1COb.jpg)
So essentially that header is wired similarly to this, requiring the use of the shielding ground wire:
(https://i.imgur.com/LHNun0T.png)
I am not sure if Pexon includes the ground shielding wire in its standard USB cables but they apparently DO include one for Realforce USB cables:
(https://i.imgur.com/Xpt6pIN.jpg)
If you have access to a multimeter, perhaps you can test a few cables you have for continuity by placing the test probes on the outer shell of the plug on each end of the cable. It seems that the way the Magicforce is designed requires two paths to ground, one for the internal USB ground pin and one to the shell of the USB plug.
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Hej & thanks!
Problem solved (on the Keyboard side to make all cables work):
Magicforce used a kind of over the top cable here.
The issue was, as suspected by Roteiche:
In a normal cable shield and ground are simply on short-circuit.
In the MF cable all 5 pins are assigned - so one is dedicated to shield (which is of no real use in a keyboard).
(minimally invasive) Solution:
You can simply swap the two wires for ground and shield on the white connector (connecting the USB socket with the PCB - see pic below)
- and there you go.
Simply unclick the wires from the connector with a needle (be careful you don't break the plastic nib that holds the wire in place) and replug them vice versa (short-circuit shield and ground).
Now it works with the MF stock cable as well as with any onther standard USB cable.
(https://i.imgur.com/Pzu1CObl.jpg) (https://i.imgur.com/Pzu1COb.jpg)
the revision topic:
my SN: 217030817 - so, seems to be only single boards then..
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Unfortunately I didn't write down the pin assignment order - but you can simply find out using a multimeter ..
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Thanks for this! Amazing Info.
I'd be interested in applying the 'mod' as well. Unfortunately I don' have a multimeter.
Do you mind sharing the pin order?
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I have this issue w/ my CM Pro S board, only likes to work w/ certain micro-usb cables - figured it was due to the pin-out on the micro end.
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Some cables have a shield which connects to the plug housing and is considered pin 5, some connect the housing to the ground wire and some simply just don't bother, these are usually the ones that don't always work.
Some cables are also too thin and unable to flow enough current, this is usually only an issue on external drives and occasionally backlit keyboards.