Question about crts in a RCA Projection TV ppr475t (Chassies model-Hitachi VP6X)
 

Hi, I have this projection tv im cleaning up and well I was looking at each crt inside it (blue,green,red) and I noticed that there is a dirty rectangle stained in the middle of each individual crt. Well I thought that maybe it was the growth in the coolant so i cracked one open, drained the coolant out, wiped down the crt and its still there. Im thinking this is image burn-in but why would it be shaped and colored like that?

Any info would be nice

Thanks, Wes

Wes -

That's just burn-in from the raster displayed on the CRT. The tubes in a projection set get driven harder than a direct-view set in order to get an image through the optics. That tube looks like it's got a few hours on it.

Somewhere there is a web page that shows burn-in patterns of projection CRTs at various levels of use. If the set showed a decent picture before, it shouldn't be too hard to get the same performance again, especially with fresh coolant.

-Jim

Thanks for the info Jim, that was exactly what I was looking for. It had a pretty descent picture before... a tad of greenish tint to it but overall pretty good for 20 some years old and free =P .

Hopefully some new coolant should make it look a little better.

1 more question though, that coolant that mcm still sells http://www.mcmelectronics.com/produc...LAID=220229728 , is that ok to use?

So, is it fairly common that the long axis of the raster is placed on the short axis of the tube in these sets? The burn pattern is rotated 90 degrees from what I would expect. :scratch2:

jr