Sony CR-45 4.7uF cap replacement for real?

[DevyDevly]

Hi All,

I really don't trust the physical size difference between these old orange caps and the new, hopefully, replacement caps (sitting on top).
Is this physical size difference ok - it seems huge?
Old 4.7uF 250V ChemiCon KX Series (40mm tall) vs new 5.6uF 400V ChemiCon KXE Series (17mm tall)
(I know the new cap is 5.6uF and 4.7uF but I got better specs on the 5.6uF cap (250 mA @ 100 kHz ripple) and figured the small difference wouldn't matter here (20%).)

I'm recapping my Macintosh II PSU Sony CR-45. These orange caps sit inbetween the 780uF 400V big mother caps AC side of the PSU.
All the new replacement caps are the same size or 10% smaller or so, but not this huge difference. I do have a 4.7uF 400V cap replacement if needed but it's even smaller (phsically) and has worse ripple specs.

Hopefully there's wise capacitor nerds out there who can help me please.

 

[GerrySch]

The change in size is simply materials improvements in the foil and electrolytic fluid. What I'm concerned about is the QUALITY of the capacitor. If it has worse ripple specs then it doesn't work as well at its rated value as your original cap. Remember, your replacement caps should be the same or a higher voltage value rating and you can go no farther that +/-20% above/below the original's Farad rated value. Voltage puts a physical stress on the plates (foil) of a capacitor and Farads is a measure of how much charge it can hold in a circuit.

When I recapped my SE/30, I used Tantalum caps as they are not prone to leaking like electrolytics but that might not always be possible. For power rail filtering (+5v, +12v, -5v and -12v), use electrolytics and use the Tants in signal processing circuits.

Good Luck,
Gerry

 

[DevyDevly]

Thanks Gerry.
I’ve purchased the best specced caps I can find (12000 Hrs @ 105°C; 100 mA @ 120 Hz; 250 mA @ 100 kHz).
I can’t find the ripple specs for the original but can’t imagine they would be better than the best available today - unless there was a different subclass of cap that use to exist and doesn’t today?

I’ll let you know if there’s success and the house doesn’t detonate… otherwise…