power supply capacitor upgrade on Quad 405-2

sberube · 16th March 2006, 05:07 PM

Hi all,

I'm currently contemplating a replacement of my Quad 405-2's power supply capacitors (original ~20 year old electrolytic caps). Now the current values are 10k uf at 50v. I'm thinking to stick a higher voltage cap (63 or 80V) and I've just noticed that I could actually get 12k uf at 80v caps from my local retailer (SMH ELECTROLYTICs). Could replacing 10k uf caps by 12k uf ones be detrimental in any ways? Or is it just going to provide the circuit with a more stable source of current?

Any comments are very much welcome before I blow up my PA

anatech · 18th March 2006, 02:40 AM

Hi Sebastien,
The 12K caps are within tolerance, don't worry about putting them in. You start running into trouble when you take big steps up in capacitance.

-Chris

sberube · 18th March 2006, 05:09 PM

Thanks alot Anatech. I'll try it next week then

ary · 19th March 2006, 12:46 PM

Yes it's all right

jacques54 · 21st March 2006, 01:51 PM

Hello Sebastien,

If you google somewhat, you will find that the power supply capacitors have been replaced with 12000 uF up to 22000 uF values. The rectifier bridge, a 7A PM7A2Q, seems to be able to cope with them.
I have put two 22000 uF/63V (EPCOS) in a 405 because they fitted nicely in the clamps (50mm diameter, 80mm height). I still need to find some time to upgrade the modules themselves.

Cheers,

Jacques

DRC · 22nd March 2006, 10:51 AM

Be sure to get high temperature caps for long life !!

forr · 22nd March 2006, 11:10 AM

Having measured the tan-delta of a lot of electrolytic capacitors, I have been surprised that how almost all of them, even the old ones, behave correctly from this point of view. Then I wonder if it is worth to change the reservoir capacitors of an amp without knowing their real state.

AndrewT · 22nd March 2006, 11:23 AM

Hi,
mirroring Drc's post, I would go for increased temperature rating rather than increased voltage.

Although 50Vdc just works an increase to 63Vdc and 105degC may pay dividends in the long term.

Now it's finding a package that matches the foortprint.

sberube · 22nd March 2006, 11:57 AM

Thanks for all the great info... The only caps I can find around here are rated 85 celcius (LPO and SHM).

As for checking for capacitance prior to replacing the caps, I just won't bother give the price of the caps... I'll end up paying at most 10$ per cap for the replacement units (12000 uF 63 or 80V).

Now would anybody recommend one brand over the other?

anatech · 23rd March 2006, 12:14 AM

Hi Sebastien,
Fresh new are better than brand name old. Just buy a good brand that's long in the industry. What choices do you have?

BTW, I am root too, but never log in that way.

-Chris

16th March 2006, 05:07 PM	#1
sberube diyAudio Member Join Date: May 2004 Location: Charlotte, NC	power supply capacitor upgrade on Quad 405-2 Hi all, I'm currently contemplating a replacement of my Quad 405-2's power supply capacitors (original ~20 year old electrolytic caps). Now the current values are 10k uf at 50v. I'm thinking to stick a higher voltage cap (63 or 80V) and I've just noticed that I could actually get 12k uf at 80v caps from my local retailer (SMH ELECTROLYTICs). Could replacing 10k uf caps by 12k uf ones be detrimental in any ways? Or is it just going to provide the circuit with a more stable source of current? Any comments are very much welcome before I blow up my PA

19th March 2006, 12:46 PM	#4
ary diyAudio Member Join Date: Jul 2005 Location: HangZhou	OK Yes it's all right

22nd March 2006, 11:23 AM	#8
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, mirroring Drc's post, I would go for increased temperature rating rather than increased voltage. Although 50Vdc just works an increase to 63Vdc and 105degC may pay dividends in the long term. Now it's finding a package that matches the foortprint. __________________ regards Andrew T.

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18th March 2006, 02:40 AM	#2
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Sebastien, The 12K caps are within tolerance, don't worry about putting them in. You start running into trouble when you take big steps up in capacitance. -Chris

18th March 2006, 05:09 PM	#3
sberube diyAudio Member Join Date: May 2004 Location: Charlotte, NC	Thanks alot Anatech. I'll try it next week then

21st March 2006, 01:51 PM	#5
jacques54 diyAudio Member Join Date: Sep 2005	Hello Sebastien, If you google somewhat, you will find that the power supply capacitors have been replaced with 12000 uF up to 22000 uF values. The rectifier bridge, a 7A PM7A2Q, seems to be able to cope with them. I have put two 22000 uF/63V (EPCOS) in a 405 because they fitted nicely in the clamps (50mm diameter, 80mm height). I still need to find some time to upgrade the modules themselves. Cheers, Jacques

22nd March 2006, 10:51 AM	#6
DRC diyAudio Member Join Date: Jan 2003 Location: UK (south west)	Be sure to get high temperature caps for long life !!

22nd March 2006, 11:10 AM	#7
forr diyAudio Member Join Date: Dec 2004 Location: Next door	Having measured the tan-delta of a lot of electrolytic capacitors, I have been surprised that how almost all of them, even the old ones, behave correctly from this point of view. Then I wonder if it is worth to change the reservoir capacitors of an amp without knowing their real state.

22nd March 2006, 11:57 AM	#9
sberube diyAudio Member Join Date: May 2004 Location: Charlotte, NC	Thanks for all the great info... The only caps I can find around here are rated 85 celcius (LPO and SHM). As for checking for capacitance prior to replacing the caps, I just won't bother give the price of the caps... I'll end up paying at most 10$ per cap for the replacement units (12000 uF 63 or 80V). Now would anybody recommend one brand over the other?

23rd March 2006, 12:14 AM	#10
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Sebastien, Fresh new are better than brand name old. Just buy a good brand that's long in the industry. What choices do you have? BTW, I am root too, but never log in that way. -Chris

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