Sony GDM-FW900 power supply MCZ3001D info needed

[Andy Cuffe]

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

[email protected]

 

[Bob Parker]

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

[email protected]

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

 

[Electric dabbler]

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.asp?page=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

 

[Andy Cuffe]

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.asp?page=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

[email protected]

 

[Electric dabbler]

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.


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