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Increase Filter Capacitance - KR-6600

gort69

gort69

AK Subscriber
Subscriber
The original KR-6600 filter caps are 8,200uf. I have on hand a pair of 15,000uf caps that will fit the clamps. I have used these 15,000uf caps in a KR-7600 w/o issue. The 7600 originals are 12,000uf. The KR-6600 and KR-7600 have identical power switches and rectifiers (and many other parts). Are there any downsides to installing these caps in the 6600? Seems like a pretty big jump. Thanks.
 
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Big caps are always tough on power switches. That's the downside.

This is always a nice addition to a unit with a hard-to-replace power switch.
 
Just picking some typical numbers that should be in the ballpark for this receiver.

The first cycle inrush current for the factory value filter capacitors would be in the range of about 30 amps.

With the 15000 micro-farad capacitors it would be in the range of about 45 amps. The better the transformer, the the higher the numbers.

These numbers can vary some, but this gives an indication of the magnitude of the increase. Luckily it only lasts for about 0.016 seconds.

I include the circuit referenced by EchoWars in most of the gear that I update and in some cases I add soft start. It may not be needed in all cases, but it give me something to do.
 
Wirehead said:
Don't forget the rectifiers. Almost doubling capacitance, will put stress on those as well.
Click to expand...
Probably a lot less stress than they can deal with. Even a lowly 1N4004 can take a 30A+ surge.

A bad rectifier is a rarity in the SS audio repair biz. Power switches, OTOH, are another matter entirely. It's here where I'd focus my concern.
 
Thanks for the replies.

I forgot to mention that I had previously installed a relay in the 6600 for the power switch.

The reason I'm considering using the bigger caps is as I mentioned - that the 6660 uses the same power switch (and rectifier) as the bigger 7600. And the 7600 as far as I have found isn't a notorious destroyer of power switches. But I should also mention the the KR-9600 also uses the same power switch, and it is notoriously tough on them. That, plus the fact that I have them on hand, they'll physically fit nicely, and it would save the cost of another order,shipping charge, etc. (Thrifty is fine but I don't want to do something stupid.)

Speaking of rectifiers, these things use this oddball little TO-3 deal.

 
Ignore the AK rectifier stress hysteria, it is completely overblown and not even a minor concern. Put the caps in, it won't hurt anything.
 
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