Focus on KDS AV-195TF

P

paul

Guest
Hi all,
KDS AV-195TF Trinitron tube
I've not worked on one of these before but I have 2 with exactly the same
symptoms.
Perfect picture, nice 'snap' (arc), picture collapses but comes back perfect
except for center area now out of focus.
Asked a friend at another shop and he said that the KDS units have trouble
with marginal FBT's.
Opened her up to get the number off the FBT (HFL1127RD) and noticed it had 2
FOCUS pots.
Saw on Sam Goldwasser's faq that some new sets have a Horiz. and Vert.
focus. New to me.
But before I go off half-cocked I wanted to know if anyone has worked with
one of these units and what they thought.
What ARE exactly the 2 FOCUS controls and can an internally arc'ed FBT cause
this asymetric. The dynamic focus circuit?
Thanks for any help,
Keith
 
Thank you for the dynamic focus trans. tip. I have been trying to get a
schematic but no luck. I don't know if it is part of the KDS flyback or not
but will look closer and investigate more for a dynamic component.
Thank you,
Keith

"John Gill" <jdgill@juno.com> wrote in message
news:71016e83.0309150705.58270357@posting.google.com...
Keith:
Most 17" and larger monitors have both a vertical and horizontal focus
adjustments on the flyback. Put a cross-hatch on the screen and try
adjusting one of the pots to see how it changes the focus on the
screen. Adjust for sharpest picture.

I did have a few Dell/Sony 17" monitors where you could adjust the center
for sharp focus and the outsides would be off. Adjust the outsides for
sharpness and the center would be off. It seems that Sony had used a
dynamic focus transformer in these sets. These small transformers would
develop small cracks in the core surrounding the windings which caused
the focus problems.

Hope this helps...
John
Click to expand...
 
?test
"paul" <kp1@mail.com> wrote in message
news:scb9b.4033$BS5.1370@newsread4.news.pas.earthlink.net...
Hi all,
KDS AV-195TF Trinitron tube
I've not worked on one of these before but I have 2 with exactly the same
symptoms.
Perfect picture, nice 'snap' (arc), picture collapses but comes back
perfect
except for center area now out of focus.
Asked a friend at another shop and he said that the KDS units have trouble
with marginal FBT's.
Opened her up to get the number off the FBT (HFL1127RD) and noticed it had
2
FOCUS pots.
Saw on Sam Goldwasser's faq that some new sets have a Horiz. and Vert.
focus. New to me.
But before I go off half-cocked I wanted to know if anyone has worked with
one of these units and what they thought.
What ARE exactly the 2 FOCUS controls and can an internally arc'ed FBT
cause
this asymetric. The dynamic focus circuit?
Thanks for any help,
Keith
Click to expand...
 
Hello: I had the same problem on this monitor. Had to change 2 transistors
at the rear of the board centered. Cant remember the number C4??? but they
are to-220 mounted on a heatsink. You can follow the circuit from the
flyback pin labeled DF. Hope this helps.
"paul" <kp1@mail.com> wrote in message
news:scb9b.4033$BS5.1370@newsread4.news.pas.earthlink.net...
Hi all,
KDS AV-195TF Trinitron tube
I've not worked on one of these before but I have 2 with exactly the same
symptoms.
Perfect picture, nice 'snap' (arc), picture collapses but comes back
perfect
except for center area now out of focus.
Asked a friend at another shop and he said that the KDS units have trouble
with marginal FBT's.
Opened her up to get the number off the FBT (HFL1127RD) and noticed it had
2
FOCUS pots.
Saw on Sam Goldwasser's faq that some new sets have a Horiz. and Vert.
focus. New to me.
But before I go off half-cocked I wanted to know if anyone has worked with
one of these units and what they thought.
What ARE exactly the 2 FOCUS controls and can an internally arc'ed FBT
cause
this asymetric. The dynamic focus circuit?
Thanks for any help,
Keith
Click to expand...
 
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