The legacy depth finder on my boat is a B&G Hecta Hornet system. It's now acting up with no depth data appearing, though it will show some info on the display LCD. After some plug and play with another unit and an oscilloscope I've now again got the proper pulses going to the transducer, but there still is no depth info ( at all) on the LCD. The 3V keep-alive battery is OK, the microprocessor seems to be working and I'm suspecting the RAM or ROM memory may be partially zapped with amnesia... the PO boat log says that a similar fault already was fixed at one time with a new ROM.
As this is equipment has already worked fine for over 20 years, I'm particularly miffed that it now would not want to continue for another 10 year or so more. What's with that? Has anyone experienced a similar fault and what was the fix? If possible, I would like to get, borrow or buy some still working or even a junked unit to fix mine. Even a circuit diagram would be fine as with that I'm sure I could fix it myself. Programming from scratch and burning a new ROM is something else again, so it would really help to have a still working ROM to burn a few spare copies. I just hate to throw out and rewire a whole system for a such a glitch, even though it may be good for the off-shore economies.
BTW: the B&G wind unit also has some issues. It all may have been caused from some EMF pulse from a near-by lightning strike, as at the same time the SSB antenna tuner, solar charge controller and the wind charger blocking diode got hit too... the battery bank actually shorted to zero volt, discharging through the wind generator armature. Surprisingly, the ancient Raytheon radar is still working.
Please let me know if you still have any of this old stuff, it would sure help. I'm in the Bay Area in CA at present, but frequently at the boat in FL as well. Of course I'll pay any reasonable costs and shipping too. My cell# is (408) 621-3558