"Andy Cuffe" wrote in message
...
On Wed, 16 Aug 2006 23:57:58 +0100, "Electric dabbler"
wrote:

Hi Andy,
All I was able to find was a schematic of a Sony
KV-27FV300/29FV300/32FV300/36FV300 power supply with this chip in the
middle, and an internal block diagram of the chip.
If either will help (probably not), I'll send 'em to you.

Bob

Thanks for the tip. I found some information a Sony training manual
for a TV using the same power supply IC. It gave some good pointers,
but nothing that helped in this case.


Hi Andy,

The manufacturer is Shindengen
http://www.shindengen.co.uk/index.as...semiconductors

Sadly no data sheet, it is very commonly used in Sony CRT TV's and I've
even
seen it used in a couple of LCD models.

As far as I remember it has three protection mechanisms:

Pin 1 is used for under voltage lockout (ac line voltage)
Pin 8 (VCC) is monitored for excessive voltage. 18V rings a bell but I
wouldn't swear to it
Pin 9 (OCP) monitors current accross the sense resistor(s) on the primary
side.I've never had much luck moitoring Pin 9 as the voltage waveform here
is tiny.


Good luck fixing it.

Philip

All those voltages were fine right up to and even shortly after shut
down. I ties the OCP pin to ground, so that should have completely
disabled OCP.

Next I replaced the two 1kV 330pF caps going from D to S on the output
FETs (C641,643). So far the power supply has been running fine, but
only time will tell. The same caps worked fine in the other power
supply, but the stress of de-soldering could have temporarily fixed an
intermittent short, or open in one of the caps.

I'm almost out of parts to replace in this thing! I'm just glad I had
a working supply to swap parts with.

Interestingly, the bad supply was manufactured using lead free solder
and the good one uses regular. The first thing I did was to re-solder
pretty much everything in the power supply (including the caps in
question).
Andy Cuffe


Hope you found it with the caps. I've had that thing happen to me, very
annoying when the faulty component fixes itself.


Philip