I'm going to go off in another direction and say that it is probably a polyswitch. Nominal resistance 3.9 ohms. used to limit the inrush current to the rectifier and capacitors on switch on. If this has failed, which is what it looks like and your fuse is blowing, then there is short circuit in the rectifier or capacitors of the SMPS.
Replace the polyswitch with a 240V incandescent bulb (say 40-60W) and if the bulb glows you know you have a short circuit, Track it down from there.
Element14 or RS should be able to supply a replacement polyswitch

 

I'm going to go off in another direction and say that it is probably a polyswitch. Nominal resistance 3.9 ohms. used to limit the inrush current to the rectifier and capacitors on switch on. If this has failed, which is what it looks like and your fuse is blowing, then there is short circuit in the rectifier or capacitors of the SMPS.
Replace the polyswitch with a 240V incandescent bulb (say 40-60W) and if the bulb glows you know you have a short circuit, Track it down from there.
Element14 or RS should be able to supply a replacement polyswitch

Thanks! I'll give that a shot indeed!

 

Have a look at this : https://www.murata.com/en-global/products/productdetail.aspx?partno=PTGL18AR6R0H8B72B0
It's on the Murata website but there are lots of similar items. It is an "electronic fuse, self re-settable" PTC device. Rated at 265V so should be OK for your mains supply. The only thing you need to find is the trip current.

 

Have a look at this : https://www.murata.com/en-global/products/productdetail.aspx?partno=PTGL18AR6R0H8B72B0
It's on the Murata website but there are lots of similar items. It is an "electronic fuse, self re-settable" PTC device. Rated at 265V so should be OK for your mains supply. The only thing you need to find is the trip current.

Thanks very much! many potential solutions! I'm starting to think I may be out of my depth here. I may need to try harder at tracking down the correct schematic and put it to rest once and for all!

 

Here is a match for the "3R9" of the part number. The "53E" could be a date code.
https://www.murata.com/en-us/products/productdetail.aspx?partno=PTGL10AR3R9M3P51B0

 

Here is a match for the "3R9" of the part number. The "53E" could be a date code.
https://www.murata.com/en-us/products/productdetail.aspx?partno=PTGL10AR3R9M3P51B0

That one has a max voltage of 53v, whatever it is I'm looking for appears to be dealing with mains voltage of 230v. We do appear to be getting close though I think!

 

That one has a max voltage of 53v, whatever it is I'm looking for appears to be dealing with mains voltage of 230v. We do appear to be getting close though I think!

56v sorry

 

That one has a max voltage of 53v, whatever it is I'm looking for appears to be dealing with mains voltage of 230v. We do appear to be getting close though I think!

and the lead configuration is different. Reversing and searching "PTGL10AR3R9M3P51B0" and looking at images shows a marking of "R3R9". So, not so sure. You have a mystery.

 

Hello,

I also noticed that the parts with 3R9 in the code are for 30 or 56 Volts.

Bertus

 

You could also try this company in Oz : https://a1tv.com.au/Panasonic_Parts_list.html
They have 2 replacement PCBs in stock (shown near bottom of page) but, as they also sell spare parts, you could see if they have a replacement CF7104 or CF7105 as marked on the PCB.

 

And this company have a service manual : https://www.schematicsunlimited.com/p/panasonic/
and I forgot to mention the manuals are a FREE pdf download !

 

Quick ebay search found 6 replacement Panasonic TNPA6072 boards from 34 Euros (but supplied from the UK).

 

https://www.allelectronics.com/item/tnr-3.9/inrush-current-suppressor-3.9-ohm/1.html

 

Quick ebay search found 6 replacement Panasonic TNPA6072 boards from 34 Euros (but supplied from the UK).

Thanks for all your help! I've actually decided to take this route as well as still try and repair the dead one just for my own interest. So there's a replacement board already on it's way.

 

Notice that the part in question appears in parallel with relay RL7101 contacts. This is common for an inrush current limiter, for which a 3.9 Ohm NTC thermistor seems quite reasonable. As the supply output approaches regulation the relay contacts close, shorting out the NTC and giving full power.