Kopin display cable failing after very little use.

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m_bishop
 
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Kopin display cable failing after very little use.

Post by m_bishop »

I did the single-eye modification on the kopin video glasses, and for a few weeks it seems to work fine. I am building a Halloween costume around them, so I have only been switching it on to make sure it works with the other components. So, this afternoon, I put the whole costume together to test it, and noticed the video kept blinking in and out.


After a little experimentation it was obvious the cable connection to the main board of the display is failing. After just a few minutes of wiggling it to verify the issue, it seems to have gotten noticably worse. The display is basically useless as is. I'm pretty upset.


I was wondering if this was a common issue with this display? Does anyone have a fix for it? Are there wiring diagrams available? I am not using the sound, so it should only be a matter of soldering the 3 or 4 wires, but the connections in that cable are too small to even attempt. If the video signal, power and ground are accessable anywhere else on the board I might be able to give it a shot.


So, I am open to any suggestions. I built a wearable pi in a shoulder holster, and put a night-vision camera under the laser scope of an air-soft, running to a switch-box so I can switch between camera view and computer view, and now that I have the whole setup working, the display fails, ruining the whole project.


Any help is welcome!

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Re: Kopin display cable failing after very little use.

Post by adafruit_support_mike »

Post a photo of the connection between the cable and the PCB and we'll see if we can think of any suggestions.

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Re: Kopin display cable failing after very little use.

Post by m_bishop »

I thought I posted this reply this morning, so forgive me if it's a repeat.


The connector is the one on the bottom board in this image:https://learn.adafruit.com/system/asset ... Board1.jpg


It looks like a micro-usb connector, but the cable can't be replaced on the original piece. It looks like this entire board may be a break-out board for the sound, but the wires coming from it are all red, except one. Do you have a wiring diagram available for this board? It might be possible to just remove the first board, and wire everything directly to the second board, if I can find out for sure that those for wires are power/ground and singnal/ground.


I know under normal circumstances asking for a replacement would be impossible, since I've already modified the unit, but if this is an unusual case of a faulty connector, would Adafruit be willing to replace it? I have only removed the case, and the second display, so far (I didn't even unsolder and re-solder the connections like in the tutorial), and I'm a little nervous that, in trying to fix it, I'll completely ruin it and be out 100$ ... of course, I'm already out 100$ due to a crappy connector if I don't. I even made a custom enclosure for the whole thing already too. I'm stuck between a rock and a hard place here.

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Re: Kopin display cable failing after very little use.

Post by adafruit_support_mike »

I know what the boards look like in general.. I'd like to see a photo of the one you have specifically. I need to see that to know whether there was a production defect that led to the connector coming loose.

In the worst case, it looks like the micro-USB connector is being used as a power jack, and we have a micro-USB breakout that would work as a connection for the wires: https://www.adafruit.com/products/1833

Let me check with the developer who did the tutorial for those glasses and see if he has more information about the signals.

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m_bishop
 
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Re: Kopin display cable failing after very little use.

Post by m_bishop »

There was no visible defect. Instead of disconnecting the sound board when I did the single-eye modification, I just used double sided mounting foam and stuck it to the video board. Then I glued it to a thin brass piece that held the screen to it. I used piano wire glued to the plastic housing of the screen to hang it off my glasses. I made a clip that allowed me to clip the cable to my glasses, so all the weight was on the clip and the piano wire.

Here it is on a model (The one on the right, obviously)

http://38.media.tumblr.com/e9f4f8def5bc ... 1_1280.jpg


I did not modify the boards at all. I would love to take more pics of it, but I tore the whole thing apart last night so I could try to figure out a way to fix it.

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Re: Kopin display cable failing after very little use.

Post by adafruit_support_mike »

I checked with the developer who did the tutorial on modding the Kopin display and he thought re-wiring the power connections to a micro-USB breakout would be the best solution.

We don't have any schematics for the unit, so you'll need to trace the connections from the micro-USB connection formerly on the PCB to the wires with a multimeter. You can confirm your readings by plugging the power connector into the micro-USB breakout and taking voltage readings between the pins.

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m_bishop
 
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Re: Kopin display cable failing after very little use.

Post by m_bishop »

I think I have a plan. I removed the connector all together, and traced the wires with my scope. I've found the video signal wires, and traced those through the sound board, which is just a breakout board for the headphone jacks. I had used superglue to fasten the brass piece to the soundboard, and it broke when I was disassembling the unit. So, with that being shot, I just traced the video signals to the video decoder board.


It looks like I can just bypass the sound board entirely. I'll lose the ability to play sound, but I lost that once I took the unit apart anyway. So, at this point, that's probably the closest to a 'solution' that I'm likely to get. For the record, the connections to the video board are (blk,red,red,red) -> (Ground, power, signal ground, signal), in the cable that's (un-shielded braid, red, green, yellow). So long as I don't break anything re-wiring that cable, I'll at least have video for the costume.


I'm still pretty unhappy the connector just failed entirely, after almost no use, forcing me to blow two nights of free time and lose sound.
Last edited by m_bishop on Fri Sep 05, 2014 9:50 am, edited 1 time in total.

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m_bishop
 
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Re: Kopin display cable failing after very little use.

Post by m_bishop »

I just want to put this here, so if anyone else ever has this problem they can see how to solve it.

Here is the cable before I put it together, so you can see the wiring. The power ground MUST be wired to the braided ground wire. I think I misspoke earlier and said it could go to the black, but last night I double checked and it must go to braided, open, uncolored, wire. Here is an example:

http://33.media.tumblr.com/a244fe39b81d ... 1_1280.jpg

Here is the finished product after re-wiring the cable:

http://33.media.tumblr.com/b6b6e8dd301f ... 1_1280.jpg


Hopefully this helps someone someday.

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