Sony KV-2730, problems with bright picture
 

Hello all,

My recently acquired Sony KV-2730 EC (a 28" Trinitron set, about 15
years old?) came to me with a broken chopper transistor in the power
supply. I replaced that, and now the set has problems with bright
pictures. I'm told the problem has existed for quite a while.

When using the scart input (AV) or channel 0 (which comes through the
tuner), and viewing a bright pic, the top 5 cm of the screen starts to
flicker, that is, it jumps around a bit sideways. When this happens, a
clicking sound can be heard from somewhere around the chopper. When
the pic darkens again, the flicker goes away. Turning contrast and
brightness up makes the problem worse. Note that channels 1 and up
don't seem to have this problem, only the scart input and channel 0!

Possibly related: Once, while I was testing the scart input, the
program I was watching had a brief all white picture. The PSU shrieked
and shut down. I had to cycle the power to get it working again.

I watch tv through my VCR, and have one of the TV's channels tuned to
the VCR's modulator. When I change channels, the set emits a short
chirp that sounds a bit like the ticking sound. And if I turn the VCR
off before the TV, I get the same shriek and the PSU shuts down.

Any ideas? A shorted chopper is something I can easily fix, but this
is a bit out of my league. And it's a nice television otherwise.

BR, Ilkka

Ilkka Huikari wrote:
Any ideas? A shorted chopper is something I can easily fix, but this
is a bit out of my league. And it's a nice television otherwise.

Weak electrolytics in the power supply.

---
Met vriendelijke groet,

Maarten Bakker.

Sounds like the AKB can no longer adjust to the lack of beam current from
the cathodes within the CRT. When a very bright area of the raster is
required the cathodes no longer can supply enough electron flow to properly
illuminate the phosphors, then the AKB attempts to equalize the current
through the three cathodes and causes the flicker.
wrote in message
l...
Ilkka Huikari wrote:
Any ideas? A shorted chopper is something I can easily fix, but this
is a bit out of my league. And it's a nice television otherwise.

Weak electrolytics in the power supply.

---
Met vriendelijke groet,

Maarten Bakker.