Author Topic: Please advise how to repair my LZ-F  (Read 1121 times)

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Offline dragonken

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Please advise how to repair my LZ-F
« on: Sun, 09 February 2020, 01:57:51 »
I bought it from someone in 2013. I use it daily in my office.

Last week it suddenly shows up "One of the USB devices attached to this computer has malfunctioned, and windows does not reconginze it". under windows 10 / windows 8.

I have soldering iron and I can buy electronic components (in case I can confirm which part of my PCB failure) in my city.

I hope folks here can provide me a solution or a way to repair this keyboard.

Thanks,
Ken235386-0235388-1

Offline gipetto

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Re: Please advise how to repair my LZ-F
« Reply #1 on: Sun, 09 February 2020, 04:27:30 »
There is a visible isp header on the pcb so you'll need to flash a bootloader, or failing that, the bootloader and firmware combined in the same hex.

Offline dragonken

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Re: Please advise how to repair my LZ-F
« Reply #2 on: Thu, 13 February 2020, 09:21:44 »
Hi, it will be great if someone can link me a step by step guideline on flashing firmware / get into bootloader for this A.87 PCB.

I did some research before posting this message and so far I just found some troubleshooting tips from winkeyless.kr. They are for B-series keyboards.

http://winkeyless.kr/how-to-check-a-pcb-is-working/
http://winkeyless.kr/how-to-check-the-hardware-is-broken/

more questions:
1) Can I just using the mini USB for flashing the firmware?
2) If not, and I have to program it by ISP? Use teensy?

Thanks in advance.

Online yui

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Re: Please advise how to repair my LZ-F
« Reply #3 on: Thu, 13 February 2020, 09:32:48 »
did you spill water on it?, i have that problem when a short happen on the usb data lines or on some usb ports on my old laptop that are just worn out (making bad contact). so maybe before going to the effort of buying a programmer and/or flashing try with an other cable (and if you did sorry then but reflashing might be a good next step if you do not nee any burn marks/lifted pads on the usb connector), and if your keyboard is not recognized as a usb device you will most likely not be able to flash it on usb. you may be able to use a teensy as an isp, i never tried
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Offline gipetto

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Re: Please advise how to repair my LZ-F
« Reply #4 on: Thu, 13 February 2020, 14:30:34 »
1) you can try, but if it doesn't work then isp is all you can do.
2) I used the teensy 2.0, but i've seen isp flashing guides for many arduinos, some as old as the uno.
https://github.com/qmk/qmk_firmware/blob/master/docs/isp_flashing_guide.md

I can't give any more advice as I'm not familiar with the manufacturer. bootmapper is a bad sign as it generally doesn't support qmk.

Offline audiosl4ve

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Re: Please advise how to repair my LZ-F
« Reply #5 on: Thu, 13 February 2020, 14:35:22 »
did you tried with another cable first?

Offline dragonken

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Re: Please advise how to repair my LZ-F
« Reply #6 on: Thu, 13 February 2020, 23:22:17 »
did you spill water on it?, i have that problem when a short happen on the usb data lines or on some usb ports on my old laptop that are just worn out (making bad contact). so maybe before going to the effort of buying a programmer and/or flashing try with an other cable (and if you did sorry then but reflashing might be a good next step if you do not nee any burn marks/lifted pads on the usb connector), and if your keyboard is not recognized as a usb device you will most likely not be able to flash it on usb. you may be able to use a teensy as an isp, i never tried

Last month I was using this keyboard for my programming job in my office. I picked up a phone call and after that I returned to programming. At this moment, I got a static electricity shock from the keyboard (the metal case). After that, the keyboard starts to malfunction.

I disconnected the USB cable and reattached it again. It shows "One of the USB devices attached to this computer has malfunctioned, and windows does not reconginze it" under windows 8.

I went to buy a new mini USB cable and plug it to test again, it doesn't work. I plug it to other desktop / notebooks with the new cable / old cable, it doesn't work either.

I am going to buy a tennsy and try to get into the bootloader mode. Please kindly help which software and which version of firmware should I use for this PCB.

It is LZ-F keyboard.

Thanks in advance.
« Last Edit: Thu, 13 February 2020, 23:25:04 by dragonken »

Re: Please advise how to repair my LZ-F
« Reply #7 on: Sun, 16 February 2020, 10:27:08 »
did you spill water on it?, i have that problem when a short happen on the usb data lines or on some usb ports on my old laptop that are just worn out (making bad contact). so maybe before going to the effort of buying a programmer and/or flashing try with an other cable (and if you did sorry then but reflashing might be a good next step if you do not nee any burn marks/lifted pads on the usb connector), and if your keyboard is not recognized as a usb device you will most likely not be able to flash it on usb. you may be able to use a teensy as an isp, i never tried

Last month I was using this keyboard for my programming job in my office. I picked up a phone call and after that I returned to programming. At this moment, I got a static electricity shock from the keyboard (the metal case). After that, the keyboard starts to malfunction.

This is one of the major downsides of customs using aluminum cases :( Several people have brought it up in group buy threads for them, if you find a solution please let us know.

Offline gipetto

  • Posts: 60
Re: Please advise how to repair my LZ-F
« Reply #8 on: Sun, 16 February 2020, 17:52:30 »
Isn't the solution to connect the shield pin on the usb cable to the aluminum case? I guess then you would have to insulate gnd from shield on the pcb to avoid ground loops.

Offline tex_live_utility

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Re: Please advise how to repair my LZ-F
« Reply #9 on: Sun, 16 February 2020, 20:08:08 »
Before you try to ISP flash, can you check that none of the USB solder joints are broken? Use the continuity check feature on a multimeter.
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Offline dragonken

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Re: Please advise how to repair my LZ-F
« Reply #10 on: Fri, 21 February 2020, 07:06:56 »
I plug the USB cable to the keyboard and check the connectivity by the two ends : solder joints on the PCB board and USB-A head. The pins are well connected like this diagram.

Sigh... the next step is to buy a teensy.
« Last Edit: Fri, 21 February 2020, 07:10:10 by dragonken »

Offline MajorKoos

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Re: Please advise how to repair my LZ-F
« Reply #11 on: Fri, 21 February 2020, 07:32:06 »
I've had this happen to me before.  It turned out to be a corrupted bootloader.
I used a raspberry pi as a AVR programmer to reflash the bootloader.

As for shorting against the case, you could try putting some shelf/drawer liner in the bottom of the case so the PCB doesn't short against it.
The only kustoms I've come across which ground the case via the USB cable are norbs. 
« Last Edit: Fri, 21 February 2020, 20:48:09 by MajorKoos »