"Bob Parker" wrote in message
...
On Fri, 11 Aug 2006 13:40:28 -0700, Andy Cuffe
wrote:

I have a Sony 24" GCM-FW900 monitor with a power supply that keeps
shutting down. It will run for anywhere from 10 seconds to 20 or 30
minutes before shutting down.

All the voltages in the power supply look fine with no ripple. The
power simply shuts off with no change in the output voltages before
shutdown. I've confirmed that the power supply is at fault by
swapping it with a known good power supply.

I've swapped all the major power supply components between the good
and bad one with no change (including the MCZ3001 control IC,
transformer, +220v rectifier, +12v regulator, +220v feedback
reference, optoisolator, output FETs and the timing cap for the
MCZ3001). All the caps test fine for ESR. All resistors measure
fine. Nothing is running hot. It's not at all sensitive to
vibration, or flexing of the board. I've even tried disabling the
over current and over voltage protection with no change.

Does anyone know where I can find a data sheet for the MCZ3001D power
supply control IC? I need to find out exactly what conditions can
make it shut down.
Andy Cuffe



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


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