Replacement 'green cap' 392J 1200V

[tiff_lee]

Hi all,

I had a logitech Z506 psu go bad due some glue corroding the legs of several components and the one i'm struggling to find a replacement for is a green polyester capacitor markings 392J 1200V.

The problem is I can't find any 3.9nF caps with a voltage rating of 1200V from any reputable retailers (plenty of 100V) , this particular cap only seems to be available from Chinese sellers which leads me to believe the rating is garbage or the cap is.

There is a thread on this particular PSU here
https://www.badcaps.net/forum/showthread.php?t=32783
but no mention regarding a replacement 'greencap'.

Any help is appreciated.
cheers, Lee

[eccerr0r]

Re: Replacement 'green cap' 392J 1200V

photo would be nice, of the original and where in the circuit it belongs.

1200V is unusual, are they using that instead of a proper Y-cap?

[PeteS in CA]

Re: Replacement 'green cap' 392J 1200V

Sounds like a PFC output cap, a film cap that parallels the big lytic, or maybe a primary side snubber cap.

Maybe look into Panasonic ECWH series parts, page 80 of this catalog, https://cdn.badcaps-static.com/pdfs/...c9731e0d95.pdf .

[tiff_lee]

Re: Replacement 'green cap' 392J 1200V

Ok some pictures attached.

yeah according to that linked thread it is part of the snubber circuit .

Thanks for the catalogue link, so ECW-H8393RJV is the same capacitance, lead spacing (7.5mm) but only rated to 800VDC. Honestly I don't know how critical that is and whether the greencap rating is even genuine. The Panasonic caps rated to 1.25kV have a 20mm lead spacing.

[PeteS in CA]

Re: Replacement 'green cap' 392J 1200V

Another possibility, https://bz.airlibro.jp/book/view_html5.php?id=466&p=19

Rubycon MPE Series

[redwire]

Re: Replacement 'green cap' 392J 1200V

Ok some pictures attached.
... ECW-H8393RJV is the same capacitance, lead spacing (7.5mm) but only rated to 800VDC....

No, that is 39nF not 3.9nF or 3,900pF which is why it is so big. But ECW-H8392 is obsolete and big too.

The voltage rating is a bit ridiculous, as if the power MOSFET is rated for that, and the pcb footprint so small. Sometimes a disk cap will be usable.

[R_J]

Re: Replacement 'green cap' 392J 1200V

The cap was likely ok, but he cut the leads off so now it is nfg. You can get .0039µf 1200v mylar or polyester caps from many suppliers.

[tiff_lee]

Re: Replacement 'green cap' 392J 1200V

Another possibility, https://bz.airlibro.jp/book/view_html5.php?id=466&p=19

Rubycon MPE Series

I'll take a look thanks

No, that is 39nF not 3.9nF or 3,900pF which is why it is so big. But ECW-H8392 is obsolete and big too.

The voltage rating is a bit ridiculous, as if the power MOSFET is rated for that, and the pcb footprint so small. Sometimes a disk cap will be usable.

Yeah my bad it was pretty late

The cap was likely ok, but he cut the leads off so now it is nfg. You can get .0039µf 1200v mylar or polyester caps from many suppliers.

You always so passive aggressive? no 'he' didn't cut the leads off why would I of done that when I had all the tools in front of me to remove it. The leads had been completely corroded by the glue and pretty much disintegrated.

I don't have an actual picture of mine but it looked similar to this but only much worse as the entire cap base was covered in the glue which had changed state into the corrosive brown stuff.

Would you care to share which suppliers you are referring to? like I said all I could find of that capacitance, with that lead spacing and voltage rating were dodgy chinese suppliers.

[stj]

Re: Replacement 'green cap' 392J 1200V

what does it do?
is it in series with the big resistor?
if it is, are the pair across a diode or mosfet?

[redwire]

Re: Replacement 'green cap' 392J 1200V

It is the primary RCD snubber network on the Logitech Z506 power supply.

D5 FR207 1kV 2A 500nsec
C3 3,900pF 1200V LS=7.5mm
R2 10R 1W
R1 51k 3W

TOP258MN datasheet they use a 3.9nF 1,000V cap plus a 200V TVS though fig39. The IC max. is 675V. It's just a cheap Logitech design and then even cheaper parts went in.

Nothing is rated 1,200V in that small 7.5mm leads, and it runs next to hot resistors, is covered in conductive glue. I would stuff in a quality film cap 1kV or ceramic disk cap 2kV there.

[stj]

Re: Replacement 'green cap' 392J 1200V

i was just thinking 2kv ceramic

[momaka]

Re: Replacement 'green cap' 392J 1200V

i was just thinking 2kv ceramic

Same here.

2 kV Ceramic should be fine... unless the design is so bad that this somehow causes oscillations on the primary (I've seen it happen on cheap 2-transistor flyback designs on the 5VSB of an ATX PSU... but those are a more special case, I think.)

If not, I think the rating could also be dropped to 630V on the film cap. As others said, nothing in the circuit is rated for that high of a voltage, so it probably isn't needed... unless the ripple current on that snubber circuit is so high that it causes lower-voltage (smaller case size) film caps to overheat.

In any case, I suggest going with a 630V quality polypropylene cap in there, and that should be fine. Polyester might work too, but PP has better high-frequency stability. If not, go with a 2kV ceramic.

[R_J]

Re: Replacement 'green cap' 392J 1200V

I'll take a look thanks


Yeah my bad it was pretty late

You always so passive aggressive? no 'he' didn't cut the leads off why would I of done that when I had all the tools in front of me to remove it. The leads had been completely corroded by the glue and pretty much disintegrated.

I don't have an actual picture of mine but it looked similar to this but only much worse as the entire cap base was covered in the glue which had changed state into the corrosive brown stuff.

Would you care to share which suppliers you are referring to? like I said all I could find of that capacitance, with that lead spacing and voltage rating were dodgy chinese suppliers.

You post someone else's picture then get pissed off at me for stating the obvious.

[tiff_lee]

Re: Replacement 'green cap' 392J 1200V

It is the primary RCD snubber network on the Logitech Z506 power supply.

D5 FR207 1kV 2A 500nsec
C3 3,900pF 1200V LS=7.5mm
R2 10R 1W
R1 51k 3W

TOP258MN datasheet they use a 3.9nF 1,000V cap plus a 200V TVS though fig39. The IC max. is 675V. It's just a cheap Logitech design and then even cheaper parts went in.

Nothing is rated 1,200V in that small 7.5mm leads, and it runs next to hot resistors, is covered in conductive glue. I would stuff in a quality film cap 1kV or ceramic disk cap 2kV there.

Thanks for jumping in and the link.

Thanks to the others for the recommendations.

You post someone else's picture then get pissed off at me for stating the obvious.

Are you ok mate? not sure what your problem is but I posted my own pictures (the glue one was for reference as I had already cleaned my board off), you took a shitty attitude before I posted the glue picture up. Thanks for contributing zero to the thread apart from the chip on your shoulder, I guess you must be the resident troll.