Philips PM-3323 DSO Blowing Fuses

[Jim Attfield]

Hoping for a schematic of the PSU section (which is a switcher) so I
can start troubleshooting. Blows mains fuse the instant it is switched
on, something has shorted out in the PSU.

Jim

 

[Jean-Yves]

Hoping for a schematic of the PSU section (which is a switcher) so I
can start troubleshooting. Blows mains fuse the instant it is switched
on, something has shorted out in the PSU.

Jim

you may have a resistor or some diodes shorted, surely one or more
diode..
easy to check with a multimeter...
verify all big resistors ans all diodes as you can have more than one
shorted...
also check the main transistor which is probably shorted too.

 

[Jim Attfield]

you may have a resistor or some diodes shorted, surely one or more
diode..
easy to check with a multimeter...
verify all big resistors ans all diodes as you can have more than one
shorted...
also check the main transistor which is probably shorted too.

Thanks, that's what I plan to do but thought I'd start a trawl for
info/schematics anyhow. It's a bit more complex than normal as the EHT
supply seems linked to the main switcher as well.

Jim

 

[Jean-Yves]

Thanks, that's what I plan to do but thought I'd start a trawl for
info/schematics anyhow. It's a bit more complex than normal as the EHT
supply seems linked to the main switcher as well.

Jim

what is the integrated circuit assuring the oscilator function in your
supply ?

 

[Jim Attfield]

what is the integrated circuit assuring the oscilator function in your
supply ?

I don't know yet, I have still to work out how to disconnect the
on/off mechanism - the rod to the front panel goes through the PCB.

Jim

 

[Fred Bartoli]

Thanks, that's what I plan to do but thought I'd start a trawl for
info/schematics anyhow. It's a bit more complex than normal as the EHT
supply seems linked to the main switcher as well.

Jim

A few years ago I reversed the PM3320A PSU. I still have the schematics, but
looking at it I didn't completly finished the work.
AFAIR it finally was the EHT transistor that was fried and made the main PSU
have vapors.

The 3320 and 3323 share a lot and almost surely have identical supplies.
Even if the schematics isn't completly finished (maybe up to 95%), it'll be
useful.
I send you a copy.

 

[Joe Soap]

In response to what Fred Bartoli

A few years ago I reversed the PM3320A PSU. I still have the
schematics, but looking at it I didn't completly finished the work.
AFAIR it finally was the EHT transistor that was fried and made the
main PSU have vapors.

The 3320 and 3323 share a lot and almost surely have identical
supplies. Even if the schematics isn't completly finished (maybe up to
95%), it'll be useful.
I send you a copy.

PM3335 manual and circuits here:

ftp://bama.edebris.com/bama/philips/pm3335/PHILIPS%20PM3335-37-SM.djvu

 

[Jim Attfield]

I send you a copy.

Fred, that's brilliant - can't thank you enough.

Jim

 

[Jim Attfield]

PM3335 manual and circuits here:

ftp://bama.edebris.com/bama/philips/pm3335/PHILIPS%20PM3335-37-SM.djvu

Thanks anyway, but I was after PM3323 and nothing there is close
enough I'm afraid.

Jim