Hi all,

I have a 15 year old Sony KV-27EXR15 TV. Been a super TV for me for
15 years.

For the past couple years, when I first power it up (cold), the video
flashes on and off about 5 times before it stabilizes and stays on.
Its not much of a wait .. probably 15 seconds or less, but could be an
indication that the tube is starting to fail ???

The main problem which has just surface in the past few days, is that
after having the TV on for a long time (say 5 to 15 hours), the
picture and sound will suddenly drop out. From the sounds coming from
the set, it sounds as though the set has been turn off, but pressing
the power button does activate the relay, and it clunks in and out
fine. For now, I push the power button so that I hear it go to the
OFF position, and wait 2 or 3 minutes. When I power it up again, the
set works fine, for hours ... maybe even the rest of the day.
However, the problem has resurfaced many times, so I know its not
going away by itself. I'm speculating that their could be a micro
fracture in either a solder joint or the PCB around the main power,
which is opening and causing the set to act like the power's been
turned off. After a short "rest period", the set cools and continuity
is restored ... for some random period of time.

I've not been into the back of this TV in the 15 years I've owned it.
My only other experience in fixing TVs was to replace a cap in the
start up circuit of my 25 year old Sony 19"TV (still working great,
but over-scanning), and removing and re-doing every solder joint in
the tuner of my Sony 13" portable TV (it now is working fine and is 14
years old).

I did a Google search for this problem on the KV-27EXR15 and didn't
come up with an answer. A couple people mentioned the blinking video
at cold start up, and on person suggested the Pic Tube was weakening,
whilst another thought it might be a bad solder joint.

I've been extremely happy and fortunate to have 3 Sony's, all of which
have given me good service, particularly the 25 year old 19" model.

Any thoughtful insites would be appreciated ...

Bill

cooncat at gmail dot com

The flashing is a weak picture tube. You may be able to adjust
the G2 (black potentiometer), on the CRT board. You may likely
have bad solder connections at the horizontal drive transformer.
Also replace the polarized capacitor in the horizontal drive. The
last two items will cause the problem you are posting, & it will
soon "blow up" the power supply. Rono.

On Mon, 30 May 2005 09:40:30 -0230, "Rono" wrote:

The flashing is a weak picture tube. You may be able to adjust
the G2 (black potentiometer), on the CRT board. You may likely
have bad solder connections at the horizontal drive transformer.
Also replace the polarized capacitor in the horizontal drive. The
last two items will cause the problem you are posting, & it will
soon "blow up" the power supply. Rono.


Thanks for the tips ... I'll give it a look. Its too bad they don't
include schematics with TVs ... my 25 yr. old 19" Sony had full
schematics that came with it. The newer Sony with the problem doesn't
have any schematics. However, I suspect that it will look similar to
the 13" model that I have been into, i.e., a mainboard and a few
daughter boards. We'll give it a look and see what we can see.

BTW, is there any way to correct the over-scanning on the 25 yr old
Sony 19" model? There are no Horizontal/Vertical size pots on the
front of the set. Perhaps there are some inside .. I do have the
schematics for this one, so perhaps I'll find my answer there.

Thanks again,

Bill