Hi....Anyone suggest approaches to repairing a couple of malfunctioning
video
sounders? I have 2 that have now failed on me for no apparent reason - a
Koden 101 and a Furuno 266. Both relatively modern units and regarded as
high
quality devices used by professionals.
The Koden is presenting full colour display with other functions and modes
like range
shifting, VRM etc all appearing to work OK, but no useful seabed image. I've
tried replacing the transducer, but no improvement. Could the output pulse
be dead and how can this be checked and repaired?
The Furuno was working well until I switched it on recently and the screen
display appeared compressed into a 4cm wide band, rather than in the full
screen width of 12cm. It was still displaying good colour and seabed detail
despite the dramatic image distortion
and all other range and mode functionality was working fine. I tried to trim
the display back into line with the edge potentiometer on the video pcb for
the horizontal gain, but it then wobbled and now presents with a totally
blank screen! Nothing, zip, no relay click when switched on - now stone
dead.
Any suggestions, apart from spending another £500 on a replacement?

Regards.....Keith