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Old 10th August 2010, 03:11 AM   #1
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Default Which caps to replace in Pioneer SA-7300

I want to improve the sound of my Pioneer SA-7300.
I already replaced all the in and out terminals to gold plated and im going to
replace the two power caps to new ones.

I was wondering if someone can help and tell me which caps are
in the signal path and can be replaced for better sound.

Here is a link to the schematics of the SA-7300:
http://www.milkbands.co.il/Pioneer-SA-7300-int-sch.pdf
and here is a high resoluion top view of the open amp:
www.milkbands.co.il/P8080006.JPG

Regards,
Roi.
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Old 11th August 2010, 01:34 PM   #2
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C17, C25, C35 on one channel and C18, C26 and C36 on the other are all 2,2uF / 10V electrolytes which are directly in the signal path. You can change them to film capacitors.

That amp is pretty old, and as I can see from the picture, it doesn't have a lot of electrolytics. If you're already changing the power supply caps, why not change them all ? The other caps are much smaller and probably all of them together won't cost as much as one power supply cap and after that modification your amp will be as good as new.

Best regards,

Dubravko
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Old 11th August 2010, 02:14 PM   #3
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First of all thanks alot.

I thought about changing them all but i started getting confused with
the types. It's easy to find another cap with the exact same volts and uf
but there are film or electrolyts, for audio or regular, low esr, high riddle...

If you can point me to the right type (if there is one right type for all the caps together) i would be more than happy.

Btw, what about disc caps? do i need to replace them too? i know that the
treble and maybe the bass pots are connected through disc caps, what do you think? i would love to improve both of them.
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Old 11th August 2010, 03:42 PM   #4
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You'd probably do well with all of electrolytics being general purpose from some of reliable manufacturers.
If you can't find the appropriate voltage rating of the cap, you can easily substitute them with ones specified for larger voltage.
For supply caps you can use 10 000uF, 8000 will be harder to find and probably more expensive. If you are worried about the load presented to the rectifier diodes by increased capacitance, don't be, it's not such large increase that it would make a problem and electrolytics usually have wide tolerance.

Oh, I just noticed, C1 and C2 (1uF) and C11,C12 (3,3uF) could also be substituted from electrolytics to film caps, but they are on the phono preamp, so you can leave them as they are if you don't plan to use turntable in your system.

Indeed, there are some ceramic (disc) caps which could also be changed to film caps, but I'd try to first change the electrolytics, and then if everything went ok, maybe go further in modding the amp.

-Dubravko
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Old 11th August 2010, 04:55 PM   #5
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What exactly is film? is it electrolyts or am i mixing things up here?
Can i replace all ceramics with film or i need only the ones in the signal path?
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Old 11th August 2010, 06:17 PM   #6
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Film capacitors are the ones that use plastic film as dielectric between metal plates. They are not electrolytic capacitors.
It is not good idea to replace all ceramic capacitors with film because on some places in the circuit (like bypassing the terminals of transistor) you have to leave ceramic because it has very low impedance up to a very high frequency.

Please read this:
http://www.diyaudio.com/oldwiki/index.php?page=[Capacitors]
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Old 11th August 2010, 09:12 PM   #7
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Can you please help me by telling me which ceramics from this scematic should be replaced to film?

If i replace all the caps in the amp, do you recommend replacing all the ceramics too?

Thanks alot!

Last edited by rg12; 11th August 2010 at 09:15 PM.
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Old 12th August 2010, 02:51 AM   #8
Pocoyo is offline Pocoyo  Indonesia
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Hi RG12
To Improve the sound
- Please change them one by one if you not an expert
- after 1 replacement then you try ( you know which wrong )
- try to use the best solder like mundorf or WBT
- for the terminal you can make a direct solder for the cable
- change the 2X 8000uf 50v to 10.000uf or 12.000uf 63v elna for audio
- change all elect cap after years they will be dry
- you can change by BG F or elna (silmic or std) for 470, 220,100, 47
- try to find efox rifa mmk for film cap (minimum)
- ceramic is good function for bypass except in signal ground

try to trace the signal there
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Old 12th August 2010, 04:07 AM   #9
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I understand everything except which ceramics should be replaced
to film and which ceramics should be replaced to the same ones but new.

Im getting all confused by the scheme....
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Old 12th August 2010, 07:18 AM   #10
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Rg12,

Ceramics that can be replaced with film caps are:

C31,C32,C33, C34, C29, C30, C27,C28

Leave the others as they are.

But, go step by step, don't change them all at the same time.
As Pocoyo already said, you might end up with a malfunctioning amp and it can be seen from your posts that your knowledge in electronics is not good, so be careful and check everything twice as you go along.
Remember that electrolytics are polarised and when you change them be careful not to reverse the polarity because they might explode in your face and make your amp unusable.

Film capacitors that I recommended for replacement of electrolytics will not fit into the place of original capacitors because of different capacitor case style and different spacing of the pins, so you can just solder the film caps so they lie horizontally on solder side of teh board. The smallest ones you will find will be with 63V rating and you can buy all of them with 63V rating as it is enough.

-Dubravko
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