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Handbox getting old?


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#1 akhnaton

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Posted 24 March 2007 - 05:34 AM

My handbox is not responding promptly as it used to do. The ENTER button needs to be pressed dangerously till it works. This is even worse on cold nights. Warming up the handbox helps a bit but still the ENTER button is giving me a lot of trouble.

Should I open the handbox and clean the kaypad contacts ?
Ishak Benbanaste
Tekirdag - Turkey
LX200GPS - 14"

#2 LukeB

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Posted 24 March 2007 - 07:02 PM

Hi,
If you feel that you are competant in technical matters and there are no warranty issues then you should open the handbox and check the state of the contacts.
Although I have not personally looked inside my handbox I have been told by several friends that have had similar problems (the ENTER and ARROW keys being the main culprits since they are the most used) that Meade have not gold plated the push button contacts and so they are prone to oxidisation which can cause these types problems. Carefully cleaning the contacts will probably resolve your problem for now but it will probably reoccur. The only real solution is for Meade to gold plate the key contacts in all future handboxes.
Cheers,
Luke.

#3 Guest_rtanton_*

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Posted 26 March 2007 - 08:09 AM

               
The conductive pads on the keypad are silicone rubber with a high content of a specific carbon black (Shawingan) to make them conductive.  Unfortunately all carbon blacks contain sulfur which causes the cure (crosslinking) of the silicone polymer to be inhibited.  The uncrosslinked polymer will eventually bleed to the surface causing the pad to become non conductive.  This a problem for all silicone keypads rexcept where silver is used in place of carbon black (military, aerospace, etc)...in these applications part cost is not critical.

Repair of the handox is an easy DYI.  Remove the phillips screws and pull out the silicone keypad.  Clean the carbon black pads (and the trace contacts on the pcb) with isopropyl alcohol.  If the pcb contacts have oxidized use a pencil eraser to clean them and follow up with the ipa.  You can improve keypad reponse by coating the carbon pads with a layer of silicone containing silver.  A kit is available from Chemtronics (p/n CW2605 about $12).  It works very well and one kit can do several keypads.  It has a very short working time after mixing...so gather all your controls (tv, radio, Autostars, etc) and do them at the same time. The red lens is loose and can easily be lost (or forgotten on reassembly).

Russ

#4 akhnaton

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Posted 28 March 2007 - 05:24 AM

Hi Russ,

I've followed your advice...  and the result is amazing. The handbox started to respond to the slightest touch. I can say that it is good as it was on the first day.

Thanks a lot...

Ishak B.
Ishak Benbanaste
Tekirdag - Turkey
LX200GPS - 14"




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