I've got a dead Garmin GPS 12map. It doesn't switch on, no display and welcome screen. I opened the case and tested the memory battery voltage, 0.5v. So, I desoldered the memory battery. After that I tested some voltages. When I push the power on button, Vcc of 80386 and AM29LV160BT are about 3.0V. Vcc of LP324 is about 25v. Frequency CLK2 of 80386 is 33MHz, CLKOUT is 16.5MHz. RESET pin is 3v, and no high-to-low transition. That's all I have tested.
Is there some service manual or knowledge to repair this GPS? I like the GARMIN GPS 12 series very much, quality PCB and components, solid case, simple and clear display. Hope it can works again.
Thank you.