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Old 11-25-2020, 08:14 PM   #1
3Phase615V
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Default Cambridge Audio Azur 550A Power Supply Cap Replacement

Hi,

I isolated a power supply failure in my Cambridge Audio Azur 550A to a shorted filter cap (C42, page 37 - see service manual attached) on the +45V supply of the right-hand channel PCB. The faulty cap is a Cambridge Audio branded "Audio Grade" 2200uF, 63V, 105C 18mmx35.5mm (see attached photo), for which CA have refused datasheet information and the supply of a replacement(s) as they advise they do not supply these items to "end users".

Since audio grade caps rarely appear available at more than 50V (105C) it has me wondering whether or not a couple of decent quality non-audio grade Nichicon or Rubycon caps will suffice in the C41 and C42 positions (my intention is to replace both +45V side filter caps to reduce any untoward imbalances between original and non-original caps).

Given that audio grade 2200uF, 63V, 105C capacitors appear to be a rare item, I am looking for suggestions for potential replacements (brand and series) that I can use in place of the original CA caps. I would think that low ESR, high ripple would the guiding parameters, but the latter can be quite a range. In other words, what is considered too low, high enough or even excessively high ripple current for a cap for this particular purpose?

So far I have been looking at the caps below, with the last two (Rubycon and Vishay) having quite substantially higher ripple current figures than the other three. Are these suitable/compatible? I am also wondering if leakage is a particularly important parameter to pay attention to for this usage:

Nichicon UVZ1J222MHD

Nichicon UVY1J222MHD

Panasonic ECA1JHG222

Vishay MAL214258222E3

Rubycon 63ZLJ2200M18X35.5

Thanks in advance for any advice and suggestions.

Tony
Attached Images
File Type: jpg CA 2200uF 63V 105C.jpg (79.5 KB, 17 views)
Attached Files
File Type: pdf azur-550a-650a-service-manual-1358510856.pdf (3.09 MB, 4 views)

Last edited by 3Phase615V; 11-25-2020 at 08:20 PM..
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Old 11-25-2020, 08:59 PM   #2
stj
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Default Re: Cambridge Audio Azur 550A Power Supply Cap Replacement

scumbags.
you dont use "audio grade" caps on power rails.
look for low impedence caps with the highest ripple current you can find - preferably with a decent lifespan not some 1000hour shit
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Old 11-25-2020, 11:51 PM   #3
redwire
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Default Re: Cambridge Audio Azur 550A Power Supply Cap Replacement

I would say the custom capacitors are for marketing wank and wooing reviewers, and for having a poor lifetime... strange it shorted.
Sonically, low ESR and high capacitance are audibly better. I think Cambridge Audio saved money by keeping them relatively small value.
Note the capacitors experience audio-frequency ripple currents (as well as mains) - so look at the 10kHz ESR spec as well for a figure of merit.
So I think an SMPS-grade capacitor is more what these are.

If it was my amplifier I would upsize the caps as 2x2,200uF per rail per channel is a bit lean, not the greatest. If you have the height see what might work.
pic from Azur 651a

edit: the problem is the small height.
Nichicon UFW1J222MHD "Audio grade" 2,200F 63V 2,000Hrs @85C but more of a placebo.
Taller, like 37.5 to 41mm MUCH BETTER:
Nichicon UHW1J222MHD 20mohm 3.86A @ 100kHz ripple. But 18x40mm high.
United Chemi-Con EKYB630ELL222MM40S 10,000 Hrs @ 105C, very low ESR 16mohm 3.67A @ 100kHz ripple. Nice. But 18x40mm. I would stuff them in lol.
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File Type: jpg Cambridge Audio Azur 651a cap pic.jpg (180.9 KB, 13 views)

Last edited by redwire; 11-26-2020 at 12:10 AM..
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Old 11-26-2020, 11:45 AM   #4
3Phase615V
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Default Re: Cambridge Audio Azur 550A Power Supply Cap Replacement

Hi stj and redwire,

Thanks for your replies and advice.

It looks like didn't miss out much with the most sensitive parameters for my particular cap requirements. I was thinking I might be better focussing on longer life caps than the ones I found first off and you have confirmed that is worth doing- thanks.

I want to try to stick with the original cap sizes (18x33.5), so I will continue looking for similar caps to the ones you have suggested, but the parameter figures are useful to me in that search, so thank you again.

By the way, I meant to type I had the Azur 650A not the Azur 550A (hence requiring the larger voltage caps).

The cause of the fault, I suspect, was a power surge or outage that caused the ring main fuse to trip while the amp was on standby. I cannot be sure though as I did not immediately use the amp in the days after the trip event.

Thanks!

Tony
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Old 11-26-2020, 06:21 PM   #5
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Default Re: Cambridge Audio Azur 550A Power Supply Cap Replacement

Quote:
Originally Posted by stj View Post
1000hour shit
Sounds like 1920s' incandescent light bulbs, LOL.
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Old 11-26-2020, 06:54 PM   #6
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Default Re: Cambridge Audio Azur 550A Power Supply Cap Replacement

just put long life ones in and call it an upgrade .
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Old 11-26-2020, 08:12 PM   #7
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Default Re: Cambridge Audio Azur 550A Power Supply Cap Replacement

how wide and tall can you actually fit?
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