Power problems with Garmin Nuvi 755 GPS

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Old 12-11-15, 04:36 PM
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Power problems with Garmin Nuvi 755 GPS

While I was driving today, I got a "low battery" message from my Garmin Nuvi 755 GPS. The power light on the GMT-20 (power supply and FM traffic receiver) was illuminated, so I got out my multi-meter (which I have only passing familiarity with) and did some poking around.

The fuse passed a continuity check, and I got 12 volts on the end of the cable that plugs into the windshield mount. The problem was, I couldn't find any voltage on the row of pins in the windshield mount that fits into the socket in the bottom of the GPS itself. Those pins are tiny and it's beyond my means to test them all and guarantee I'm only checking one at a time and not also touching either of the adjacent pins, so I'm thinking there is a possibility that whatever pin(s) were hot (if any were hot), the current was finding less resistance going back into the adjacent pin instead of through the multi-meter. I did see a blink on the multi-meter, bit only once and could not get it to repeat.

In the meanwhile, I hooked up the GPS to a PC via USB and it seem to function normally.

I don't know for a fact that there are no rheostats of ICs or whatnot inside of the mount, but it seems really strange to me that it should break or go bad. Anybody every hear of the circuitry in a Garmin mount going bad? Or do you have any troubleshooting suggestions?
 
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Old 12-11-15, 04:46 PM
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I have a similar model that doesn't use the cradle system but uses a miniature USB connector.
Mine only has the one mini connector.

Does your traffic power supply fit directly into the Nuvi without using the dock ?

In checking around.... the only problem I saw mentioned several times was an issue on the side of the dock where the cord connects. It appears the weight of the cord may crack the solder on the jack.
 
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Old 12-16-15, 07:27 PM
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By yimminy, PJmax, you were right. Since the cradle obviously was useless as is, I prised it apart. That socket had come adrift, and the connections are about 10-fold too tiny for someone of my (lack of) soldering skill to repair. That gall-danged suction cup will not stay put, don't make no matter how clean the windshield is, especially when the car sits in the sun, and I didn't have sense enough to remove the GPS from the cradle when I left it parked for a spell.

I already found a replacement on eBay for $20, delivered. Without your help, I wouldn't even have known to call it a cradle, so I wouldn't have known what to look for as a replacement. Much obliged!
 
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Old 12-16-15, 08:56 PM
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You're very welcome.
 
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Old 12-24-15, 11:23 AM
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I have the GPS's power supply hard-wired into my dash and the power cord emerges from a seam on the end of the dash that's only exposed when the driver's door is open. My usual mounting place is in the lower left corner of the windshield. So when the suction cup gives way and the GPS falls, its fall is arrested by the power cable which, obviously, jerks on the socket. So when the new cradle arrived, I thought to beef it up a bit to prevent it being damaged in the same way. I took it apart and put a drop of hot glue on either side of the power socket, securing it to the PCB. Then I threw a heavy bead of glue on the inside of the back half of the plastic cradle where it faces with the top of the socket, then snapped it back together quickly before the glue cooled.

I earlier had taken a shot in the dark at repairing the old cradle in the same fashion, hoping that if I accidentally got the socket back in the correct position, all those tiny little pins might be back to making contact. It obviously didn't work, but when I too it back apart, the socket remained attached (by the hot glue) to the back half of the cradle shell. Just out of curiosity, I tried to pull the socket off. It took a pretty fair amount of effort, so I'm hopeful this mod will make it more durable.

Plus I tethered the mount to a windshield defrosting vent located just underneath my usual mounting point. Provided that holds, it should prevent the GPS falling far enough for the power cord to go taught.
 
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Old 12-24-15, 11:55 AM
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The additional glue should help and the tether.... like a leash. Name:  xmas_wink.gif
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