Thread: Garmin User. "Can't unlock maps "

Until i read that you've already opened it to check, my reply was going to be just that, i.e. to look for corrosion. So, the power switch and media card slot both becoming inoperative must be just coincidental.

It may be that the SD slot has some internal corrosion or dirt so give it a good spray with dedicated Electrical Contact Cleaner. You can use Isopropyl Alcohol instead but it's not as good. DO NOT use a product like WD40 or RP7 though. While the cleaner is in the slot don't power the device on. Get and old SD Card and work it in and out multiple times then when the slot's completely dry (blowing air into it helps) see if the card is recognised.

To help you further, i need some more information because i've never worked on a 556s chartplotter. Is this a Mass Storage device (i.e. the internal memory shows in Windows Explorer) or is it a "region-only"device?

Mass Storage or Region-only terms are only referencing how the device operates. Modern Garmin automotive/handheld/offroad navigators are quite different in their basic operation to that of all classes of earlier devices. Many marine devices operate on that original principle of having specific regions (like little separate partitions) in their memory, used for dedicated storage i.e. they are Region-only. For example, in region-only devices, the basemap file is in region 3, on-board primary detail map usually in region 49, voices in region 17, etc. The other type (Mass Storage) has a visible file system where all such essential basic files including map *.img files are contained in one large region, usually 48 or 83, and then other small multiple regions have particular purposes. That main region is browsable by computer, as is the media card when it's inserted too. However, 'region-only' devices treat the card as just another region, usually it's 10. That's quite certainly the case with your chartplotter seeing it doesn't even have a USB socket.

Now that you understand how your chartplotter works, you'll realise that if there's a problem with its flash memory that it's not possible to re-format it like a Mass Storage Mode (MSM) device to overcome file corruption, bad blocks etc.. So even if in fact there is only some very simple corruption within the memory there's no easy way to correct it. In your case maybe it's a hardware failure though, it might be the flash chip has a physical fault rather than a soft corruption.

The "can't unlock maps" message means that the on-board primary map/chart itself is being seen by the device but the associated *.UNL file (containing the unlock code) for the *.IMG map file, is either corrupt, unreadable or missing entirely from region 49 (or wherever it's stored in your plotter).

It simply isn't possible to dump (i.e. copy) regions to check contents and then re-upload clean files when the device lacks a way to connect directly to a PC and there's no functioning media card slot.

I just had a look around to see IF there was a USB attachment that you could export files "fish spots and the like" but there isn't, and that means one can't even see IF you could see a mass storage.
Unless it has a Wi-Fi setting? can't even find a downloadable manual.

Might be time to update M8

AI Overview
The Garmin GPSMAP 556s is a discontinued model. The most direct current replacements, offering similar 5-7 inch, sunlight-readable touchscreen functionality, are the
Garmin ECHOMAP UHD2 7″ or 9″ series (e.g., ECHOMAP UHD2 75sv/75cv) or the GPSMAP 753xsv.
Here are the best current available options for upgrading or replacing the 556s:
Direct Upgrades (Same Size/Better Features)

Garmin ECHOMAP UHD2 7" Series (72cv/75cv/75sv): These are the most modern, direct replacement, featuring faster processors, built-in Wi-Fi for ActiveCaptain, and advanced sonar options (ClearVü/SideVü).
Garmin GPSMAP 753xsv: A more premium 7-inch option within the GPSMAP line, offering high-resolution mapping and networking capabilities.

Key Considerations for Replacement

Transducer Compatibility: The 556s uses a 6-pin connector. While older transducers might work with an adapter, new ECHOMAP/GPSMAP units generally use 8-pin, 12-pin, or UHD transducers. Replacing the unit may require upgrading the transducer for best performance.
Mounting & Power: The new 7-inch units are larger than the original 5-inch 556s. A new flush-mount installation or a modified bail mount may be required.
Mapping: The 556s uses BlueChart g2. Modern units come with built-in Garmin Navionics+ mapping.

For the closest feature set, the Garmin ECHOMAP UHD2 7" is the recommended, current-generation alternative.

Sell more fish to buy a new one.

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Originally Posted by Magnetron

......
Unless it has a Wi-Fi setting? ......

Nope, no wifi capability. All updates for charts, firmware and other software are done via SD transfer. Being he has a 556s ("s" is for Sounder) it is NMEA-0183/2000 compatible but that's only a CAN-Bus type backbone connectivity for Marine devices which connects them to multiple sensors, autopilots, engine instruments, sounder transducers etc., unfortunately it's not capable of interfacing with a computer for MSM like USB can.

can't even find a downloadable manual.

Here:

Code:

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