Author Topic: Magellan GPS 315 teardown/repair  (Read 1905 times)

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Offline tk175672

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Magellan GPS 315 teardown/repair
« on: November 06, 2015, 10:39:17 pm »
Sorry for any grammer/spelling mistakes as I am only a teenager and I am rushing to write this in between school.

I recently purchased a GPS 315 from a ham radio festival for about 1USB. The man said it worked as he used it for APRS for years. I got it home, powered it up and all i got was a screen with a single black line on each side. My first test was to see if it worked at all. It responds to all menu inputs correctly (as judged by beeps) and the lcd back-light settings work fine. I updated the firmware as well as downloaded GPS locations (none to download as power had been gone for a year or so) but it at least worked. So i knew it wasn't software it had to be hardware.

So i opened up the case and found that it is decently simple inside. A mixture of off the shelf components (a simple max boost converter and a few OP AMPS) and custom rolled chips (magellan CPU and another smaller chip) and higher end stuff (volatile memory for storage and another chip for firmware) Even had fun probing parts of it with my custom scope. (input impedance is only 5k ohm or so. I need to be careful i don't overload circuits with it.)

So I took a look at the screen. Bare silicon die controller and the funky flat ribbon connector (like they use on calculators. just held down by glue.) and i thought "A Ha that must be it.". So i started probing and one pin wasn't connected properly. When i pressed it down the screen would "scan" as long as i pressed it down but when i let go it would freeze. I heated the connector and pressed it back down and now the screen mostly works. I get the "Alert" word at the top telling me it lost power and a few horizontal lines near the bottom but nothing else. Most of the messages/text near the top work fine but nothing near the bottom displays. but yet they aren't dead either as when i turn it on they display the "garmen" logo REALLY dim. If i push on the screen and then remove pressure it displays exactly what it should display (that weird thing with LCD's where if you press on them they invert colors) but it isn't mechanical as i have tested all the connections yet it isn't electrical as it will work when i press on the screen so i am afraid it is the LCD controller.

Any advice as i don't really want to chuck it as it would be nice to learn to interface with a micro-controller. (as well as have a GPS :) always wanted one)
 

Offline Rasz

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Re: Magellan GPS 315 teardown/repair
« Reply #1 on: November 07, 2015, 11:49:43 am »
Who logs in to gdm? Not I, said the duck.
My fireplace is on fire, but in all the wrong places.
 

Offline tk175672

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Re: Magellan GPS 315 teardown/repair
« Reply #2 on: November 07, 2015, 12:43:36 pm »
Wow for a 720p webcam it takes terrible pictures... I will have to upload better ones later but I don't have time now.
 


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