Kathy K has an elderly Furuno radar (1750 I think). The scanner is a 1.5 KW
open array. The radar has worked fine until this summer. Now every once in
a while the display goes dim. Only the edges of object are bright with
dimmer interiors. Then after awhile its all bright again.

Does anybody have an idea what's happening?

--
Phil Keys
Kathy K, Willard 36

wrote in news:-
:

Then after awhile its all bright again.


Probably a bad high voltage capacitor in the anode power supply of the
CRT....or....the salt corrosion has caused a leakage path for the anode
voltage the power supply can no longer overrun....or....the picture tube
has a shorted element in the gun.

How'm I doin'?

This poor thing has been to sea a lot of years, eating away at its guts in
the salt air. Even old sailors get to retire some day....



--
There's amazing intelligence in the Universe.
You can tell because none of them ever called Earth.

wrote in message
.. .
Kathy K has an elderly Furuno radar (1750 I think). The scanner is a 1.5
KW
open array. The radar has worked fine until this summer. Now every once
in
a while the display goes dim. Only the edges of object are bright with
dimmer interiors. Then after awhile its all bright again.

Does anybody have an idea what's happening?

--
Phil Keys
Kathy K, Willard 36

Sounds like the STC control circuit is unstable. Seems like there was a
screwdriver adjustment pot under a little clip on cover (front panel) as
well as the knob control. (whew, it's been a long time) Pots (both
screwdriver and knob operated) are not forever, but often temporary (real
temporary) cures can be achieved by turning them from one end of travel to
the other 35 or 40 times..... sort of cleaning up the card and/or wiper.
The screwdriver one is pretty fragile, and is easily damaged with a clumsy
screwdriver, and broken pcb traces right at the pot can cause interesting
display problems.
Again, it's been more than 10 years since I was a Furuno fixer, 1st
class, so I could be all wet. Again.

Old Chief Lynn