tube dirty sony kpr-4110

[[email protected]]

I have one of these rear-projection tvs. It seems the antifreeze coolant has
left some grime on the inner lens, murking up the display horribly on at least
two tubes.

The lens appears to be glue-sealed to the tube, with screws to add small
quantities of coolant. It needs to somehow be removed so I can clean off the
grime and reseal it... I don't want to try to pry it off and risk damaging the
lens.

Can someone suggest a solution? Is this something I can do myself with limited
tools or should I just send off to a service bureau?

FeSS

 

[Leonard Caillouet]

A KPR 4110 is a pretty old set. The tubes are probably all near the end of
their useful life anyway. You may be seeing the typical phosphor browning
that occurs on all tubes as they age. I have never seen contaminated
coolant on a Sony CRT. Likely you will need to replace all three tubes
anyway if you replace one. It is hardly likely that you will be able to
white balance a set of this age with a new tube and two old ones.

If you can find a good servicer that will give you a free estimate, get it.
Otherwise, I'd start looking for a new set.

Leonard Caillouet

 

[Arthur Jernberg]

A lot of Sony and Phillips products do suffer from bacterial growth in the
coolant fluids and discolouration of the fluid, most severly in the blue but
also in the green and red. They both have numerous bulletins regarding that
fact. I do agree that this set is fairly old and probably will not be cost
effective to put all 3 tubes into it.

 

[[email protected]]

The blue and red tubes are gone. It indeed does look like bacterial growth.
Can someone suggest a dealer for used Sony parts? Any idea how much I should
expect to pay used?

Leonard, if you service Sony can you cut me a deal? I'm a starving college grad
looking for a job... Just bought my first tv.

Thanks!

 

[Andy Cuffe]

I have one of these rear-projection tvs. It seems the antifreeze coolant has
left some grime on the inner lens, murking up the display horribly on at least
two tubes.

The lens appears to be glue-sealed to the tube, with screws to add small
quantities of coolant. It needs to somehow be removed so I can clean off the
grime and reseal it... I don't want to try to pry it off and risk damaging the
lens.

Can someone suggest a solution? Is this something I can do myself with limited
tools or should I just send off to a service bureau?

FeSS

It is possible to disassemble these, but it's a lot of work. You have
to cut as much of the silicone RTV as possible with a sharp blade, then
pry it apart. Once it's apart, there's a glass plate that's glued in
that will have to be removed for cleaning. It's easy to break, so work
carefully. If you do break it, it's not a big deal, just reassemble it
without it. You will have to clean out all the old silicone and seal
any pits in the metal with silicone. I think the sony fluid reacted
with the metal and caused it to go cloudy. Once all this is done, just
reassemble it with silicone, let it dry and refill with fresh fluid.
MCM electronics has it for about $10 a bottle. 2 of the big bottles
should do all 3 CRTs. Of course, remove the lens before you start all
this. If you need more information, there are a few posts that you
should be able to find on google groups. These look pretty good if the
CRTs are good. You have nothing to lose as it's probably not usable as
it is.

 

[Alan Harriman]

It is possible to disassemble these, but it's a lot of work. You have
to cut as much of the silicone RTV as possible with a sharp blade, then
pry it apart.

I've done a couple of these myself. I found I could cut the RTV around the lens
assembly with a sharp utility blade fully extended. The deposits can be cleaned
by soaking with denatured alcohol and gently wiping with a soft cotton cloth. As
mentioned, be sure to clean and seal the small pits within the coolant chamber.

To reassemble, apply a bead of RTV around the mating surfaces and carefully
place the lens over the opening. There are small stand-offs as I recall, which
properly space the gap between the two surfaces. Allow to cure for at least 2 or
3 days before filling with coolant. , I used a large hypodermic syringe to fill
thru the small screw openings. To allow for heat expansion, do not fill to the
very top, but just enough so you won't see an air bubble when the CRT is tilted
in it's mounting position.

Also, I recommend obtaining the coolant from Clarke Electronics, see
http://www.picturetubes.net/ . He sells it for $5.95 a pint which I find to be
much more optically clear than the MCM brand. Do all three CRT's, otherwise you
may find the optical characteristics of the replacement fluid slightly different
from the original, resulting in minor geometry and convergence issues. Finally,
be sure to check for any leakage after a day or two of running

Alan Harriman



Once it's apart, there's a glass plate that's glued in

 

[JURB6006]

RE: KPR4110 coolant problem

I've done about 7 of those type of sets. Green and blue, as expected. These are
totally sealed with no bellows or expansion chamber, well there is but it is
within the aluminum housing. There is enough of an air pocket to keep it from
blowing apart, or blowing in the face of the CRT.

You don't need to "match" the coolant, especially in these sets, the
super-concave lens is made of plastic, so the refractive index of the coolant
is not critical. HOWEVER, if you assemble an SD174 without the inner glass you
will get an error in optical focus overall, and when you go to correct it, you
will find that you can't get it right in the center and the edges at the same
time. This might be correctable, and if that cooling system worked and kept the
phosphor from burning, I think you might be quite pleased with the picture once
you're done.

That particular piece of glass is not rquired for the optical system, it is a
cooling system component. The convection of the coolant effectively cooled the
screen, quite a bit more effectively than modern sets. If you really look at it
before you clean it you can see the patterns.

That piece of glass does change the <u>effective</u> distance from the screen
to the lens system, and glass being denser than ethylene glycol, I would assume
it lengthens it. As such, it should be correctable by shims between the CRT
assembly and the projection lens.

JURB