RCA projection TV repair question - PFR 100

[jay]

Hi All,

I was able to isolate a fault in the RCA PFR 100 projection TV thanks
to a suggestion by James Sweet, The Drive transistor on the Red CRT
neck board was shorted out. After replacing it I see the image but
looks like the image is horribly out of convergence, but before I
attack that problem I need some advice on what I am seeing with the
service switch on.

There is a switch on one of the control boards to switch the TV to
service mode, I figured that in service mode I would see a single
horizontal line but what I see is

http://www.geocities.com/shroffja/rca_service_mode2.jpg

The contrast shows up better without the flash here

http://www.geocities.com/shroffja/rca_service_mode1.jpg


Can someone help clarify what could cause this behavior, also can
someone help me with the convergence tuning sequence. There is a row of
16 pots and maybe there is a way to quickly narrow down the
combinations.

Thanks
Jay

 

[Andy Cuffe]

On 14 Feb 2005 05:25:04 -0800, "jay" <jshroff@hotmail.com> wrote:

Hi All,

I was able to isolate a fault in the RCA PFR 100 projection TV thanks
to a suggestion by James Sweet, The Drive transistor on the Red CRT
neck board was shorted out. After replacing it I see the image but
looks like the image is horribly out of convergence, but before I
attack that problem I need some advice on what I am seeing with the
service switch on.

There is a switch on one of the control boards to switch the TV to
service mode, I figured that in service mode I would see a single
horizontal line but what I see is

http://www.geocities.com/shroffja/rca_service_mode2.jpg

The contrast shows up better without the flash here

http://www.geocities.com/shroffja/rca_service_mode1.jpg


Can someone help clarify what could cause this behavior, also can
someone help me with the convergence tuning sequence. There is a row of
16 pots and maybe there is a way to quickly narrow down the
combinations.

Thanks
Jay

That line looks pretty normal to me. Sometimes you will see a little
retrace above or below the main line. It looks like the CRTs are set
too bright there. You should adjust the screen controls so the line
for each color is just slightly visible when looking in the lenses.

Convergence takes a lot of patience and practice. First, cover up the
red and blue lenses and adjust the green so the cross hatch has good
geometry. Also, adjust the vertical and horizontal size so the
picture just fills the screen. Then converge either the red, or blue
to the green with only the color your adjusting and the green visible.

Are the pots labeled? If not you'll have to figure out what they do.
Most of them should be for the red and blue and will adjust size,
linearity, pincushion, keystone, bow and skew plus maybe a few other
fine adjustments.

Mark everything before you start in case you make it worse.
Andy Cuffe

baltimora@psu.edu <-- Use this email address first

acuffe@gmail.com

 

[jay]

Andy Cuffe wrote:

That line looks pretty normal to me. Sometimes you will see a little
retrace above or below the main line. It looks like the CRTs are set
too bright there. You should adjust the screen controls so the line
for each color is just slightly visible when looking in the lenses.

Convergence takes a lot of patience and practice. First, cover up
the
red and blue lenses and adjust the green so the cross hatch has good
geometry. Also, adjust the vertical and horizontal size so the
picture just fills the screen. Then converge either the red, or blue
to the green with only the color your adjusting and the green
visible.

Are the pots labeled? If not you'll have to figure out what they do.
Most of them should be for the red and blue and will adjust size,
linearity, pincushion, keystone, bow and skew plus maybe a few other
fine adjustments.

Mark everything before you start in case you make it worse.
Andy Cuffe

baltimora@psu.edu <-- Use this email address first

acuffe@gmail.com

Hi Andy,

Thanks for the hints.

As you can see from the pictures I see a squished oval ( two curved
lines intersecting at the two ends of the projection screen) rather
than a single horizontal line, are you saying that's the way it works
on projection TV's?

Sorry this might be a very basic question but I do not have a service
manual to refer to on what the output should look like with the Service
switch on.

Thanks
Jay

 

[Andy Cuffe]

On 14 Feb 2005 11:20:28 -0800, "jay" <jshroff@hotmail.com> wrote:

Hi Andy,

Thanks for the hints.

As you can see from the pictures I see a squished oval ( two curved
lines intersecting at the two ends of the projection screen) rather
than a single horizontal line, are you saying that's the way it works
on projection TV's?

Sorry this might be a very basic question but I do not have a service
manual to refer to on what the output should look like with the Service
switch on.

Thanks
Jay

It looks to me like one line is much brighter than the other. I think
if you turn them down, the extra line will either disappear, or be
much less noticeable. Either way, it's not a sign of a problem.
Andy Cuffe

baltimora@psu.edu <-- Use this email address first

acuffe@gmail.com