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Author Topic: repair broken siig minitouch pcb  (Read 1710 times)

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Offline chimera15

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  • Posts: 1441
repair broken siig minitouch pcb
« on: Mon, 14 February 2011, 01:44:00 »
So a while ago I bought a minitouch that was non functional from a fellow geekhacker.  He only sent me the board and plate and switches, but I thought I'd try to repair it nonetheless if at all possible.

It's completely non functional.  I've tried every possible way to get it to function and tried to physically examine the board to find evidence of damage somewhere to no avail.  

I started probing the board with a multimeter and trying to compare my results to a functioning siig.  I found that there was voltage between switch terminals and most places on the board where there shouldn't be any.  Voltage between switch terminals is 1.5v where on a functioning minitouch it's barely noticeable if any.


There's only one diode on the board.  My thoughts is that it failed, other than that there's 2 large caps and 2 small caps and a lot of resistors, and of course the chip.

Anyone know anything about electronics that can help me diagnose this better.  Anyone think the chip is destroyed, or a way to test it?
Logged
Alps boards:
white real complicated: 1x modified siiig minitouch kb1903,  hhkb light2 english steampunk hack, wireless siig minitouch hack
white with rubber damper(cream)+clicky springs: 2x modified siig minitouch kb1903 1x modified siig minitouch kb1948
white fake simplified:   1x white smk-85, 1x Steampunk compact board hack
white real simplified: 1x unitek k-258
low profile: 1x mint m1242 in box
black: ultra mini wrist keyboard hack
blue: Japanese hhk2 lite hack, 1x siig minitouch pcb/doubleshot dc-2014 caps. kb1903, 1x modified kb1948 Siig minitouch
rainbow test boards:  mck-84sx

Offline chimera15

  • Thread Starter
  • Posts: 1441
repair broken siig minitouch pcb
« Reply #1 on: Mon, 14 February 2011, 02:51:53 »




Anyone know how to tell the rating on the diode?
Logged
Alps boards:
white real complicated: 1x modified siiig minitouch kb1903,  hhkb light2 english steampunk hack, wireless siig minitouch hack
white with rubber damper(cream)+clicky springs: 2x modified siig minitouch kb1903 1x modified siig minitouch kb1948
white fake simplified:   1x white smk-85, 1x Steampunk compact board hack
white real simplified: 1x unitek k-258
low profile: 1x mint m1242 in box
black: ultra mini wrist keyboard hack
blue: Japanese hhk2 lite hack, 1x siig minitouch pcb/doubleshot dc-2014 caps. kb1903, 1x modified kb1948 Siig minitouch
rainbow test boards:  mck-84sx

Offline chimera15

  • Thread Starter
  • Posts: 1441
repair broken siig minitouch pcb
« Reply #2 on: Mon, 14 February 2011, 03:30:16 »
I desoldered the diode and tested it.  It looks like it's alright.  .5 volts one way, overloard the other.  So that leaves the resisters and caps to test.   Is there a way to test caps?
Logged
Alps boards:
white real complicated: 1x modified siiig minitouch kb1903,  hhkb light2 english steampunk hack, wireless siig minitouch hack
white with rubber damper(cream)+clicky springs: 2x modified siig minitouch kb1903 1x modified siig minitouch kb1948
white fake simplified:   1x white smk-85, 1x Steampunk compact board hack
white real simplified: 1x unitek k-258
low profile: 1x mint m1242 in box
black: ultra mini wrist keyboard hack
blue: Japanese hhk2 lite hack, 1x siig minitouch pcb/doubleshot dc-2014 caps. kb1903, 1x modified kb1948 Siig minitouch
rainbow test boards:  mck-84sx

Offline chimera15

  • Thread Starter
  • Posts: 1441
repair broken siig minitouch pcb
« Reply #3 on: Mon, 14 February 2011, 03:45:44 »
I checked all the resistors.  They all seem to be resisting.  The green one is suspicious.  It's only 1 ohm.  It's gold, black, brown, red.  Anyone know what that's supposed to be?

In fact I think it may be really suspicious, because if I just put the leads of the multimeter together it's .4 ohms.
« Last Edit: Mon, 14 February 2011, 03:47:57 by chimera15 »
Logged
Alps boards:
white real complicated: 1x modified siiig minitouch kb1903,  hhkb light2 english steampunk hack, wireless siig minitouch hack
white with rubber damper(cream)+clicky springs: 2x modified siig minitouch kb1903 1x modified siig minitouch kb1948
white fake simplified:   1x white smk-85, 1x Steampunk compact board hack
white real simplified: 1x unitek k-258
low profile: 1x mint m1242 in box
black: ultra mini wrist keyboard hack
blue: Japanese hhk2 lite hack, 1x siig minitouch pcb/doubleshot dc-2014 caps. kb1903, 1x modified kb1948 Siig minitouch
rainbow test boards:  mck-84sx

Offline chimera15

  • Thread Starter
  • Posts: 1441
repair broken siig minitouch pcb
« Reply #4 on: Mon, 14 February 2011, 03:53:02 »
Alright, looks like it should be 21 ohms according to the resistor calculator here. http://www.hobby-hour.com/electronics/resistor_color_code.php
Logged
Alps boards:
white real complicated: 1x modified siiig minitouch kb1903,  hhkb light2 english steampunk hack, wireless siig minitouch hack
white with rubber damper(cream)+clicky springs: 2x modified siig minitouch kb1903 1x modified siig minitouch kb1948
white fake simplified:   1x white smk-85, 1x Steampunk compact board hack
white real simplified: 1x unitek k-258
low profile: 1x mint m1242 in box
black: ultra mini wrist keyboard hack
blue: Japanese hhk2 lite hack, 1x siig minitouch pcb/doubleshot dc-2014 caps. kb1903, 1x modified kb1948 Siig minitouch
rainbow test boards:  mck-84sx

Offline chimera15

  • Thread Starter
  • Posts: 1441
repair broken siig minitouch pcb
« Reply #5 on: Mon, 14 February 2011, 04:06:07 »
Strange, couldn't find any 21 ohm resistors on ebay.  I found some 27 ohm ones though.  My feelings are that the second band could be either brown or purple/violet...

Yup, looked at it under a magnifying glass, definitely purple, so 27 ohms.  Now I wonder how many watts.   Going to go with .5w and hope that's alright.
« Last Edit: Mon, 14 February 2011, 04:10:48 by chimera15 »
Logged
Alps boards:
white real complicated: 1x modified siiig minitouch kb1903,  hhkb light2 english steampunk hack, wireless siig minitouch hack
white with rubber damper(cream)+clicky springs: 2x modified siig minitouch kb1903 1x modified siig minitouch kb1948
white fake simplified:   1x white smk-85, 1x Steampunk compact board hack
white real simplified: 1x unitek k-258
low profile: 1x mint m1242 in box
black: ultra mini wrist keyboard hack
blue: Japanese hhk2 lite hack, 1x siig minitouch pcb/doubleshot dc-2014 caps. kb1903, 1x modified kb1948 Siig minitouch
rainbow test boards:  mck-84sx

Offline chimera15

  • Thread Starter
  • Posts: 1441
repair broken siig minitouch pcb
« Reply #6 on: Mon, 14 February 2011, 04:54:28 »
Based on the test of the resistor I had high hopes, and desoldered the chip from one of my working boards and soldered in the chip from the bad board in hopes that I could prove that that chip was good as well.   Ended up that it wouldn't recognize, so unfortunately that's the end.  It's a bad chip.  Anyone have any spare minitouch chips? lol


I suppose I could reprogram a teensy to work with the pcb...lots of trouble though...
Logged
Alps boards:
white real complicated: 1x modified siiig minitouch kb1903,  hhkb light2 english steampunk hack, wireless siig minitouch hack
white with rubber damper(cream)+clicky springs: 2x modified siig minitouch kb1903 1x modified siig minitouch kb1948
white fake simplified:   1x white smk-85, 1x Steampunk compact board hack
white real simplified: 1x unitek k-258
low profile: 1x mint m1242 in box
black: ultra mini wrist keyboard hack
blue: Japanese hhk2 lite hack, 1x siig minitouch pcb/doubleshot dc-2014 caps. kb1903, 1x modified kb1948 Siig minitouch
rainbow test boards:  mck-84sx

Offline chimera15

  • Thread Starter
  • Posts: 1441
repair broken siig minitouch pcb
« Reply #7 on: Mon, 14 February 2011, 06:51:09 »
So I've got a lot of boards with similar sized chips.  Anyone know how important the resistor and capacitor layout is?  Anyone know if it would be possible to reprogram these chips somehow?  What do the resistors and capacitors do on an older board like this?  I'm used to seeing modern boards with only chips on them, why would they need so many resistors?

I'm kind of curious if I soldered in a chip from another keyboard what would happen. lol
Logged
Alps boards:
white real complicated: 1x modified siiig minitouch kb1903,  hhkb light2 english steampunk hack, wireless siig minitouch hack
white with rubber damper(cream)+clicky springs: 2x modified siig minitouch kb1903 1x modified siig minitouch kb1948
white fake simplified:   1x white smk-85, 1x Steampunk compact board hack
white real simplified: 1x unitek k-258
low profile: 1x mint m1242 in box
black: ultra mini wrist keyboard hack
blue: Japanese hhk2 lite hack, 1x siig minitouch pcb/doubleshot dc-2014 caps. kb1903, 1x modified kb1948 Siig minitouch
rainbow test boards:  mck-84sx

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