I have an EM-406A GPS that won’t seem to turn on. It has 5v power going to it, but the little LED glows almost imperceptibly and there is no serial output. The unit only draws some 12ma now, not the normal 50-ish. What is wrong?
I had successfully interfaced the GPS to my Kenwood TH-D7 Ham tranceiver, tapping into the Kenwood’s battery (a 6xAA-cell 3rd party pack) for power. The power to the GPS was regulated by a 78L05 regulator to 5V. All was well.
I thought I’d see how well the batteries would hold up under the combined load. Using freshly charged 2700 mAh batteries, I let the radio and GPS sit on my desk all day, running. The GPS was out of lock most of the time.
About 20 hours later it shut down. I wasn’t watching at the time, but both the radio and GPS had turned off (no glowing LEDs, no display). I recharged the batteries and turned them both on. The tranceiver is fine. The GPS is not.
Did something happen to the GPS during the power down? It appears to be in some kind of sleep mode, but I gave it no commands. In fact, the receive serial line is disconnected; I only used the NMEA Tx and power/ground wires.
What am I missing?
Thanks,
Greg.