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Recapping guidelines

belgianbrain

belgianbrain

AK Subscriber
Subscriber
I opened up my Yamaha A-700 for a second general cleaning and ESR testing on the weekend.

Generally, any of the capacitors except for the smallest ones (physically) measured about 0 ohms. Even the giant 22,000 uF power smoothing caps measured 0 ohms.

The smaller capacitors (typically 0.47 or 1uF) measured about 2-3 ohms (they were all the same), except for two (different colour - seemingly different brand) measured about 5-6.

What would one replace in this situation? They all test "good" (nothing above 10 ohms), but the 5-6 ohms is obviously borderline and I wonder if all the others testing 2-3 ohms would have tested the same when new, since they're all in the same small range...

Those of you who are experienced in refurbing this stuff - what do you do?
 
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I just replace them all, particularly if the equipment is over about 20 years old, which is everything I would usually work on at the moment.

I don't have an ESR meter, and think that for the price of one worth having, you could buy an awful lot of caps.

There are people here who do measure caps and only replace those that test bad - which is fine.

Just my 3 ha'pence worth.
 
Hyperion said:
I just replace them all, particularly if the equipment is over about 20 years old, which is everything I would usually work on at the moment.

I don't have an ESR meter, and think that for the price of one worth having, you could buy an awful lot of caps.

There are people here who do measure caps and only replace those that test bad - which is fine.

Just my 3 ha'pence worth.
Click to expand...

Good point, but what about the larger more expensive caps that are testing 0 ohms. Is there any point to changing them?
 
Something you can only know with experience, I am a rank amateur at this, and tend to go by age of the cap more than anything else. However, I know large smoothing electrolytics can last longer than their PC mounted counterparts.

There are plenty of professionals here, and highly experienced amateurs who have their own take on capacitor replacement - perhaps they will chime in.

As for me, I replace all my caps with Panasonic FC wherever possible, seldom change value except sometimes for main smoothing caps. And only if forced (by availability?) I increase the voltage rating of the replacement cap - and then by no more than 25% or so. And I do replace some electrolytics with film caps where feasible. I sometimes replace 2 series electrolytics with a single better quality non-polar electrolytic. I have never used a non-polar electrolytic to replace a single polar electrolytic.

That's me - anybody else ?
 
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Most of the caps are either 36V or 50V. I was planning on changing everything with 50V caps just to make it easier.
 
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