Sony CR-45 4.7uF cap replacement for real?

DevyDevly said:

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?

Click to expand...

You are right to not be trusting. I dislike the modern tiny caps that replace the old huge one's because the ESR is often lower on the old caps. But the biggest issue is cooling, for boards that get hot. The bigger the cap, the more surface area, and the easier it is to keep them cool.

So why I try to do is go up in voltage when selecting replacements so as to get a physically larger capacitor. And that often helps solve the Lead Spacing issue too, but not always. As you pointed out in your last post, there are reasons why you may need to do a little drilling to make a replacement fit.

When choosing replacements keep your on on ESR when you review those hi-temp and hi-Hour caps because what I often discover is those caps have a bit higher ESR than the ones with lower 85°C ratings and lower hours. So its a balance between the Temp/Hour/ESR ratings.

Thank you for your kind words and for the added info.

Normally, it's best to retain the stock capacitance value when possible, unless you have a schematic and know the operation of the circuit in question. But capacitors normally have a 20% tolerance, so if your replacement measures right at 5.6uF or below, your replacement is still within the tolerance spec of the original 4.7uF capacitor. It may not matter much at all because it very well could be that they chose 4.7uF back then only because a 5.6 or higher capacitance cap wouldn't have physically fit in the space available. Very possible.

The UTi260B thermal camera I have is very nice, but it takes a while to get used to it. There's a setting in the menus which tells the camera how far it is from the device being measured. When I first got my camera, I didn't pay strict attention to that, and I think that contributed to my getting some questionable results. I've refined my usage of it over time, and the measurements are better and more repeatable.

Thermal cameras are like good desoldering guns (e.g., FR-301 from Hakko), they are very nice to have, but they set you back a lot of money. I'm a real penny pincher, and it took me YEARS to get the FR-301, but it really changed my desoldering work for the better. Fantastic tool. I get less use from my 260B thermal camera, but when I need to measure heat from multiple components at once, it's the right tool for the job. And then of course when you want to measure the output of power supplies before and after a recap, having a good oscilloscope like a Rigol DHO804 is invaluable.

All of this is why the hobby can get rather expensive. It's not worth getting all those fancy tools for only one or two vintage Macs in one's collection, but when you have multiple Macs, you tend to do a lot of work on them, and then the tools start to make more sense.