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geekhack Projects => Making Stuff Together! => DIY Discussions ARCHIVE => Topic started by: didjamatic on Thu, 03 June 2010, 09:26:19

Title: 3 keys dead after switch swap
Post by: didjamatic on Thu, 03 June 2010, 09:26:19

I just did a full switch swap of Dampened ALPS from an AEKII into a Geek Hack Space Saver (SIIG Minitouch) so I could use it at work where you can hear a pin drop and they are tiring of my very loud clicks and shenanigans.  

Did the full swap and all but 3 keys work.  E, D, C are dead.  Replaced all 3 switches, still dead.  

2 share 1 common land, the other does not.

Any suggestions?

Yeah, I know I have some flux to cleanup and some soldering could be prettier.
(http://lh5.ggpht.com/_-sQ6TN93LvU/TAe5-q07s5I/AAAAAAAAAx0/rjUxU0WHB54/s800/Soldering1_markup.jpg)

Title: 3 keys dead after switch swap
Post by: Rajagra on Thu, 03 June 2010, 09:57:27

I suspect there is a bridge on the other side of the PCB where I've drawn a dotted red line here:



That would put all 3 switches in the same line, and there might be a break where I've drawn the circle.

I don't think there is static damage to the IC, or more than 3 keys would be affected.

Do you have a multimeter? Using one to check that there is an electrical connection where there should be would help isolate the problem quickly. Buy a cheap one if you have to, you don't need anything fancy, just one that measures resistance.

Title: 3 keys dead after switch swap
Post by: didjamatic on Thu, 03 June 2010, 11:31:53

I had done a full switch swap, I didn't swap any of the ALPS internals.

Raj, you were dead on, there is a bridge where you thougth there was and there was a break exactly where you thought there was.  The break was just below the circled terminal and must have happened when i was removing a switch that still had some solder on a terminal that pulled part of the trace from the edge of the hole.  At first I was going to do a very short repair so I scraped some of the trace to do that but decided to add a wire going to another terminal and it's working perfectly.  In fact, I'm typing on it now.

Thanks a ton!  Now my neighbors in silent rubber dome land can work in peace and quiet... for now. :)

(http://lh5.ggpht.com/_-sQ6TN93LvU/TAfXy-tOCEI/AAAAAAAAAx4/TDHth5UX4sE/s800/Soldering2_markup2.jpg)

Title: 3 keys dead after switch swap
Post by: didjamatic on Thu, 03 June 2010, 14:59:02

Total about 2.5 hours.  I'll post photos later.

Title: 3 keys dead after switch swap
Post by: Harry_Y on Wed, 09 June 2010, 16:40:18

How I fix a trace:

1. Scrape the coating off the trace to get to bare copper

2. Use a short piece of wire to bridge the gap and solder in place.

3. Coat the area with Nail polish (I usually use clear)

Title: 3 keys dead after switch swap
Post by: chimera15 on Wed, 09 June 2010, 18:41:05

Yeah that can happen with minitouches cause the pcb's aren't very robust, so careful with that. Glad you got it solved.