I had the similar problem. It was caused by a bad solder joint for the power connector on the motherboard.
If you have the technical skills, some time, a pen soldering iron and some solder:
Power the unit off via the little switch in the back.
Remove the 4 corner screws, don't remove the screw on the antenna hinge if you don't have to, I don't think it was necessary, and was difficult to get back together correctly.
There is a rubber plug in a hole in the antenna niche, there is an adjustment screw underneath. Do not turn this potentiometer, or you may screw up the calibration of the GPS.
Carefully pop open the case to the navman. You may have to squeeze the bottom of the case at the sides to do this, I don't suggest prying with a screw driver as this will mess up the case.
Look at the power connector and you will probably see a solder joint, which is broken. Just re-solder the joint, and put back together.
Try to solder it as quickly as possible as heat can screw up the plastic connector, or the wire traces on the board very quickly. Also, you do not need to glob the solder on, look at all the other joints and try and copy that same look. Probably 2mm worth of rosin core solder wire will do the trick.
Also, just a disclaimer. If you haven't soldered before. I suggest you practice playing with a soldering iron, and some old circuit boards before attempting this, use google for tips on soldering. OR take it to a certified electronics repair center and ask them to fix it.
Some guy, December 2007
