Is a Polyester capacitor a good replacement for a Paper Capacitor?

[gkmaia]

I got to replace a vintage cap that goes into the rectification block of a vintage computer power supply.

I can source the KEMET Paper Capacitor 470nF 275V ac ±20% Tolerance P409 Through Hole +85°C

https://au.rs-online.com/web/p/products/8788032/

Would be smarter to get something more "modern"? Like a 470nF Polyester Capacitor PET 250V ac ±10%

https://au.rs-online.com/web/p/polyester-film-capacitors/6225069/

[T3sl4co1l]

Where is it, across-the-line?  You may want an MKT or MKP style X2 rated capacitor.  If it's part of a resonant circuit, you may need better performance (polypropylene, rated for whatever current).  Otherwise, probably fine and generic, yeah.

Tim

[gkmaia]

It the C38 bellow.

Note the schematic has it as 0.1uf, while the one I removed had 0.470uf. May have been a different revision, but the wiring is similar.

[Kleinstein]

It is a filter cap directly acorss the line. So it must be X1 or X2 class rated. These can be polyester.

.470 µF would be rather large, possibly even a little unsafe (may get a slight shock touching the plug just removed from the mains). Something like .22 µF should be OK too.

[T3sl4co1l]

I'd replace it with same value.  It may not be a hazard due to the circuit (at a glance, no idea), and it's a low risk anyway (but it is indeed a thing, and can be quite surprising ).  MKT or MKP, X1/X2 rated.

Tim

[sergioag]

It is a filter cap directly acorss the line. So it must be X1 or X2 class rated. These can be polyester.

.470 µF would be rather large, possibly even a little unsafe (may get a slight shock touching the plug just removed from the mains). Something like .22 µF should be OK too.

That's correct. Also, C37 and C38 should be class Y because they connect to ground. Since you're already there, it pays to be careful and make the thing safer.