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Old 2nd September 2010, 07:27 PM   #1
liquias is offline liquias  Israel
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Default Cyrus two - non polar cap

Hi,
Last night i horridly found out that c43 (470uF 6v DC feedback filter cap ?) has gone bad. (Swollen and cracked on both channels). I need to replace them both of course.
However, i do not have such easy access to non polar caps where i live.
I am wondering if it would be too horrible to replace it with a polarized capacitor (the neg pole being connected to the 1k resistor).
Can it harm anything or Deteriorate the sound quality?
Will it effect the life span of the cap ?

P.S.
There are quite a few sources for the service manual on the net, some of them specify that this cap is polar, some don't (meaning its non polar).

Thanks -
Liquias
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Old 3rd September 2010, 12:11 AM   #2
lohk is offline lohk  Europe
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These are the infamous red roederstein caps - good sound but not for eternity.
I am pretty sure that you can replace them with polar elcaps, like it is done in so many other amps. Panasonic FC with 470yF/6.3V are available at rs-components, Vishays at farnell Israel.
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Old 3rd September 2010, 12:15 AM   #3
lohk is offline lohk  Europe
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You amp seems to be quite old now. I would suggest that you also change the c53 and c55 (100yf) on both channels with Panasonic FC.
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Old 3rd September 2010, 01:25 AM   #4
Pocoyo is offline Pocoyo  Indonesia
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try Black Gate N 470uf 16v in Michael Percy Audio Ordering Information or
try Black Gate N or NX 470uf 6.3v in Parts ConneXion - The authority on hi-fi DIY parts and components
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Old 3rd September 2010, 04:03 AM   #5
liquias is offline liquias  Israel
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Default I agree

It does, seem that my amp is suffering from old age symptoms. I guess all Cyrus two models will suffer the same symptoms soon, none of them are very new these days...

I will look for the panasonic or vishay caps ASAP, I work allot with Farnell Israel.

I wasn't sure why a non-polar cap was chosen in the first place, as far as i know non-polar caps usually play an important role when polarity changes allot and regular polar caps would boil and burst for half of the time... I must say, i can't see how this is the case in this example.
Is it a DC feedback filter cap ? Why were the originals non-polar ?

Dear lohk and pokoyo:
Thank you guys (lohk, I seem to be thanking you allot these days ).
I will replace the other two caps mentioned above.
I do prefer not to use black-gates, I don't mind the price but I read they are out of business and any stocks anyone carries of BG is an old stock. I'm sure I will be able to find some other good quality caps, Please let me know if you think this is a mistake...
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Old 3rd September 2010, 08:15 AM   #6
Pocoyo is offline Pocoyo  Indonesia
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Hi

you can change the caps with panasonic FC, it is ok
but if you had more budget try them both
BGN didnt have depreciation cause of age
but they got big influance by computer caps
(they order too small until Rubycon didnt produce anymore)
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Old 3rd September 2010, 05:16 PM   #7
lohk is offline lohk  Europe
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I experienced that not only the value of a cap is important but somentimes also the voltage. In several big studio consoles it makes a significant difference to use the right value: Low voltage elcaps in non-biased circuits sound much better.
Thats why Henry Azima did "voice" the Cyrus amps deliberatly with these low voltage bipolar elcaps. So maybe the low voltage is more important for the sound than if it is polar or not. I should start a thread about this sometimes.
The Cyrus amp also uses 2y2F bipolar elcaps as input capacities. A good quality foil cap should be better here. But maybe this was also a deliberate decision.
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Old 3rd September 2010, 05:26 PM   #8
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Hi, if they are cracked I suppose they were chosen too low in voltage. Normally only the caps that are directly at the power supply lines crack or fail. In other words: the big filter caps. It won't hurt to use non polar 16V electrolytic caps and they won't crack because of overvoltage.

BG does not deteriorate as standard caps do. If you can get hold of them you probably have the best caps you can use at that spot. However, I think they will be way too large physically. Another very good technical and musical choice is Nichicon MUSE ES non polar caps. They won't break the bank with $ 0.72 each !

http://www.hndme.com/productcart/pc/...&idcategory=40

I also would like to suggest to replace all electrolytic caps as they are quite old now. There is nothing worse than a good repair followed by the same error of another cap. The total costs are low anyway and it will eventually cost less time. And if you don't replace all caps regret will follow if a bad caps takes some semiconductors with it to the electronic nirvana. I would replace C31 and C57 for Wima MKS2 5 mm pitch polyester film caps. As always BG N series 2.2 or 4.7 uF is a good but expensive choice here. You can replace all polar caps by Pana FC or the likes. You really can't go wrong with Pana FC/FM. You can use somewhat larger values for C53 and C55 if they fit physically.

Even if Azima did "voice" the amps please bear in mind that this was in 1988. Caps have changed and you won't find the same ones. Even if you do they will also be too old to use.
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Last edited by jean-paul; 3rd September 2010 at 05:46 PM.
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Old 3rd September 2010, 05:39 PM   #9
lohk is offline lohk  Europe
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I agree on BGs and also on the Nichicon MUSE non polar elcaps - I have very good experiences with both.
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Old 23rd October 2010, 01:33 PM   #10
jamal is offline jamal  Singapore
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hi, according to the Cyrus 2 service manual that I checked, the 470uF 6v DC feedback filter cap is not install. it is missing in the circuit diagram.
this 470uF 6v DC feedback filter cap is presence in the Cyrus 1 only.


Quote:
Originally Posted by liquias View Post
Hi,
Last night i horridly found out that c43 (470uF 6v DC feedback filter cap ?) has gone bad. (Swollen and cracked on both channels). I need to replace them both of course.
However, i do not have such easy access to non polar caps where i live.
I am wondering if it would be too horrible to replace it with a polarized capacitor (the neg pole being connected to the 1k resistor).
Can it harm anything or Deteriorate the sound quality?
Will it effect the life span of the cap ?

P.S.
There are quite a few sources for the service manual on the net, some of them specify that this cap is polar, some don't (meaning its non polar).

Thanks -
Liquias
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