On 01/06/11 10:54, Adrian C wrote:
On 01/06/2011 07:40, Richard Skeen wrote:
A friend of mine has a Sony TV (model KV-28CS70U) which suddenly stopped
working the other day. Every time he tries to turn it on, it turns
itself off again, and the power/standby LED flashes red/green.

From the service manual for KV-28LS60B same chassis (AE-6B) free on
http://www.eserviceinfo.com

Thanks for the previous responses - the service manual was useful as it
contains full schematics as well as the table of fault codes. In case
anyone is interested, here's where I've got so far...

The LED fault code is 4 flashes, "No Vertical Sync". However, googling
suggests that this error can also be shown if there's a failure of
horizontal drive, and that is what appears to be the case here.

There are two 0.47 ohm 1/4W resistors (paralleled) between the 135v B+
supply and one end of the primary winding of the flyback transformer.
These are both open circuit. The other end of that winding goes to
ground via the horizontal output transistor. So, hopefully the problem
is simply that the transistor has failed shorted, blowing the resistors,
as opposed to there being a problem with the flyback.

So, next step looks like finding a replacement 2SC5696-CA transistor.

Rich.