"burned" spot Raymarine radar screen

[Steve]

Yesterday I was checking on the boat at her slip. I turned on the electronics to be sure they were ok.Tthe lower helm has a monochrome Raymarine RL 70 radar/gps/chartplotter, in the center of the screen there appeared to be a "burned" spot. The radar image came on and was normal on the outer edges but showed a reversed (like a film negative) image in the burned area. It was ok a couple of weeks ago when I tried it last. I didn't have a chance to check the flybridge unit also Raymarine 70 but color display. This is old stuff, probably 2003 original supply with the boat and I have been thinking of changing it out before too long but it has all worked fine. I am curious what could have caused it? Any ideas, I am quite sure there have been no close lightning strikes, I didn't try the VHF but the stereo works fine, same for fridge, lights, etc.
Thanks for any ideas!

 

[RT Firefly]

Greetings,
Mr. S. Not a radar expert by any means but if the display is a CRT unit, as the tubes age, the phosphor coating eventually burns/degrades due to bombardment with electrons and the area of most frequent and constant bombardment is the center of the screen of course.

 

[Steve]

Thanks, that does make sense but it is curious that a couple of weeks ago it was fine, turn it off next time on it is "burned".

 

[Xsbank]

Have you got the gain turned way up? Almost all of the adjustments on those old monochromes are manual, might just need a bit of fiddling?

 

[C lectric]

RTF is right I think.

The same can happen to an analogue or crt based oscilloscope when some one jacks up the brightness and it gets left that way for too long.

The brightness should be kept at the minimum needed to see properly.

If it is only at the centre does it matter? If the target is at the centre you have another problem.
The phospors may simply have reached their saturation level at the centre yet the rest of the screen should continue to do its job well.

On our older crt equipped machines the data box divider lines burned in over the years yet the part of the screen that displayed the changing data worked well.

 

[mike66]

The RL 70 is a LCD display with grayscale screen. You could try the reboot procedure that is in the manual... it involves holding the on button for a certain amount of time if I remember correctly. There's also a Raymarine support site that might help.