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  Sticky keys on Lowrance LMS-350A

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Author Topic:   Sticky keys on Lowrance LMS-350A
Frank O posted 06-26-2006 10:40 PM ET (US)   Profile for Frank O   Send Email to Frank O  
My 1995 21' Outrage came with a roughly 10-year-old Lowrance LMS-350A unit that seems to work fine except for one detail. Two or three of the numeric keys on the keypad don't work. So although it's possible to save a current position and do a variety of other operations, it's not possible to manually enter a set of numbers.

Lowrance tells me they no longer do any work on LMS-350A's, so sending it to them isn't an option. I suppose I could upgrade to a currently available unit (the Lowrance person on the phone suggested an LMS-334C as a roughly comparable unit), or pick something from another manufacturer, but I'd hate to throw out a perfectly good device because of this nit.

So I'm wondering how feasible it would be to open up the LMS-350A to try to get any corrosion off the key contacts. Is this likely to be accessible, or is it all part of a sealed membrane? Thanks for any possible input.


Frank O posted 07-02-2006 02:07 AM ET (US)     Profile for Frank O  Send Email to Frank O     
I doubt anyone was holding their breath on this one, but in case anyone was mildly interested ...

I pulled the LMS-350A out of the boat today and brought it home. The keypad is of a type I've seen in some PC keyboards -- there's a sheet of film with a matrix of traces, over which is laid a rubberized sheet. When you press a key, the rubber sheet depresses and causes a small carbon-type button to press against the matrix, completing a signal path.

I tried cleaning the film sheet/matrix/buttons with a cleaner designed for 35mm slide film. I'm somewhat doubtful it's going to work, though -- there are actually three keys in a row that don't work (7, 8 and 9), which suggests to me that instead of being a dirty spot there might be a severed trace where the film's traces connect to a ribbon cable. Unless I can figure out which connectors on the back are +12v and ground (the manual doesn't help), I'll have to wait until I get back over to the boat next week to see if it helped.

If not, maybe it's time for an electronics upgrade. I don't mind the expense, but am not looking forward to mounting a new transducer and pulling cable.


deepwater posted 07-02-2006 10:59 AM ET (US)     Profile for deepwater  Send Email to deepwater     
did you think of a computer repair place ,, call best buy and ask someone on the geek squad

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