Rifa capacitors at it again - Thomson TX92 TV set

[ben]

Had a bit of an unpleasant experience this evening. We went out mid-morning and returned about 7pm. The moment we got to our landing we could smell burnt electronics, it was unmistakable to me at least!

Opened the flat with trepidation and was greeted by a stronger smell. A hurried check of the rooms, however, gave no obvious indication of a source. The living room seemed to be the strongest so I went for the devices that were connected up and powered - the VCR and and set top box. Whipped open the VCR PSU and found a worryingly familiar sight - an X2 cap burnt open. This was labelled PME but in all other respects was identical to the newer type RIFA.

The VCR is, just like the TV in the previous post, a Thomson construction from the early-mid 1990s. This one was a SABA but they were sold as Ferguson and Telefunken too. In this case the only consequences were some smoke damage to the cabinet the stuff was sitting on, but this could so easily have been more serious - the fumes were so strong they filled half a building and had it occurred when we were asleep last night, who knows what could have happened. If you have any of this kit in use please give it the once-over.

[MrBungle]

Oh that's interesting. Not seen one of those ones explode yet. Added to "replace now" list.

[Refugee]

I get the impression that all X 2 capacitors are replace of over 10 years old with ones that are date coded in human readable form.
I use flyback caps normally used in CRT screens from old computers.

[McMurdo]

a quick look at the datasheet shows the white PME range to be metallised paper..just like the gold ones.

[turretslug]

Amongst the accepted abbreviations for capacitor dielectrics, could it be that "PME" is that for metallised paper?

[Lloyd 1985]

I’ve got loads of stuff of this vintage, and with that style of cap in

Regards
Lloyd

[Argus25]

Originally Posted by Refugee

I use flyback caps normally used in CRT screens from old computers.

This is a good idea because these are usually a type of poly cap where they have a low ESR with the incoming wires bonded to the foils and many are rated at 1500v to withstand the often near 1.2kv flyback peak in the color monitor. So likely using this sort of cap as a replacement for an X2, you would never have any trouble with it after that.

[Refugee]

I have got a good supply of NOS 1600V 6n2 ones.
They get rid of the hash on MW and LW from my vacuum cleaner.
I have no need to buy any X 2 caps right now.

[Maarten]

Originally Posted by turretslug

Amongst the accepted abbreviations for capacitor dielectrics, could it be that "PME" is that for metallised paper?

MP is for metallised paper, PME is probably the name of this particular series.

[factory]

This one must have given someone a stinky surprise.

I'm not to worried about removing it at the moment, as the HP signal generator it's in has the infamous cracked plastic gear problem, while it works at the moment it can't be long before they fall to bits too.

David

[Ted Kendall]

And another one - my trusty Studer A810 workhorse, used regularly and well-kept. No warning, usual smoke, stink and general fireworks. I'm beginning to feel like Arnie in that silly FCA advert - "Do It NOW!"

[chriswood1900]

It seems to be an all too familiar smell nowadays, one I have had several times recently in both test equipment and consumer items such as my wife's sewing machine. Even more worrying is the fact that I keep some spares bought from proper sources such as RS or CPC and they had split in their packaging without even being powered and must be less than 5 years old!
Chris

[Refugee]

Those caps do split open even if laying NOS in a drawer.