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Posted to sci.electronics.repair
JamesQB
 
Posts: n/a
Default 1cm lighter vertical band on right edge of screen

Hi everyone

I have a problem with my television set. It's a Daewoo 2594ST model
using the CP775 chassis. Service manual can be downloaded for free
from he http://www.eserviceinfo.com by entering the
model or chassis number in the datasheet search field, or I can email
the whole manual or just the schematics in PDF format upon request.

There's a 1cm vertical band which is lighter than the rest of the
screen at the right-hand edge. It tapers slightly as it gets toward
the bottom. Also the top-right corner has a couple of columns of
pixels not lighting as though corner adjustment is off, and the same
towards the middle of this right-hand edge, as though pincushion
needs adjusting, although this goes when the overall screen
brightness increases and the picture 'breathes'.

I thought maybe the corner and pincushion might need adjusting, or
since it tapers slightly, maybe even the trapezium adjustment, but I
can't do geometry adjustments without a "Remocon" service
remote according to the service manual, and I've never seen this
lighter band effect when geometry is out before. I have seen
something like it when horizontal linearity was over-adjusted on a
set, as though the picture was folding over at the edge or horizontal
centering was adjusted too far over to one side causing that side to
have a siilar effect to this, but all that seems ok - channel logos
are in the correct positions.

Only one thing in the sci.electronics.repair FAQ sounds slightly
similar but the cause (electrolytic decoupling the 205V supply to CRT
base amps) isn't the case in this set as substitution today of the
10uF, 250V one with a known good replacement made no difference. Two
more caps on the same feed on the CRT base itself are also good.

Anyone got any ideas please?

Regards,
James