AU-D907 LIMITED vs 919

[ghamilton]

Can some of the electrolytics on the amp board be replaced with non-polar caps?

 

[Hyperion]

Can some of the electrolytics on the amp board be replaced with non-polar caps?

If by 'non-polar' you mean Film Capacitors, the answer is yes. I am speaking only of C07,C19,C33 and C08,C14,C34. And if you don't want to do them all, C33 & C34 changed to PET or Polypropylene type will almost certainly make the biggest difference.

 

[ghamilton]

If by 'non-polar' you mean Film Capacitors, the answer is yes. I am speaking only of C07,C19,C33 and C08,C14,C34. And if you don't want to do them all, C33 & C34 changed to Polypropylene type will almost certainly make the biggest difference.

Thank you sir. And can you tell me exactly the series of wima?

 

[Hyperion]

Thank you sir. And can you tell me exactly the series of wima?

I updated my post to add PET dielectric, as Polypropylene are out of stock (at Mouser) or far too big for the 2 locations C33 & C34.

This one is just about perfect (for C33 & C34 only), having a 5mm lead spacing, and being small overall.
https://www.mouser.co.uk/ProductDetail/WIMA/MKS2C041001F00KC00?qs=sJjjjplDs9tjpiSDkqFHRg==

 

[ghamilton]

 

[ghamilton]

I updated my post to add PET dielectric, as Polypropylene are out of stock (at Mouser) or far too big for the 2 locations C33 & C34.

This one is just about perfect (for C33 & C34 only), having a 5mm lead spacing, and being small overall.
https://www.mouser.co.uk/ProductDetail/WIMA/MKS2C041001F00KC00?qs=sJjjjplDs9tjpiSDkqFHRg==

Thank you sir.

 

[Hyperion]

Another point of view...
https://audiokarma.org/forums/index...of-a-sansui-au-919.698011/page-2#post-9414298

 

[ghamilton]

Well I got it open and the amp module heatsink out. It's very intimidating! It's been a few years.

 

[ghamilton]

Is C33 34 the only places I can put bipolar because I may use some of those green electronics?

 

[JoseHH]

If I were you I would not change that since what you have is perfectly ok. If you want to change them, then skip electrolytic capacitors for C33 and 34 which are only 1uF. If you want to use better capacitors there, then follow what Leestereo suggests which is use film capacitors like wima or kemet or panasonic with 5mm lead spacing. You could go with PET because the polypropylene film capacitors are more likely be too big to fit there.
Just be careful not to lift the pads on the PCB.

 

[ghamilton]

All those caps that I put in there still look new.
If I were to change those caps then how can I be sure how much difference in sound is caused by the driver transistors change? It may be wise to just put those transistors in and leave the caps in there. I for one want to know if the transistors make a difference.
What do you guys think?

 

[kevzep]

All those caps that I put in there still look new.
If I were to change those caps then how can I be sure how much difference in sound is caused by the driver transistors change? It may be wise to just put those transistors in and leave the caps in there. I for one want to know if the transistors make a difference.
What do you guys think?

Only change one thing at a time is my philosophy.
But then again, you might not want to spend that much time, fitting one thing, trying it, pulling apart and swapping more things.......I feel the combination of the two may give you some nice results, enjoy it, and don't worry about what might be the contributing factors.

 

[ghamilton]

I noticed that C05 & 06 are those clear plastic caps (different looking) are 100pf. At least that's what the service manual say they are. I am thinking about replacing them with 100pf silver mica.
What kind of caps are these strange looking things?

 

[Hyperion]

Only change one thing at a time is my philosophy.

And a very good philosophy it is.

What kind of caps are these strange looking things?

Polystyrene - the best dielectric there is - putting Silver Mica in there would be a significant downgrade.

 

[ghamilton]

And a very good philosophy it is.
Polystyrene - the best dielectric there is - putting Silver Mica in there would be a significant downgrade.

So what would be a good replacement?

 

[Hyperion]

So what would be a good replacement?

There is no better replacement - simply put 'Polystyrene' - The Best Dielectric There Is

 

[ghamilton]

There is no better replacement - simply put 'Polystyrene' - The Best Dielectric There Is

So you are saying to leave them in there?
And you think I should replace just those transistors and try it before replacing the caps? That's a lot of trouble!

 

[Hyperion]

So you are saying to leave them in there?

Yes.

And you think I should replace just those transistors and try it before replacing the caps? That's a lot of trouble!

Entirely up to you, and how you want to play it.

 

[ghamilton]

Yes.
Entirely up to you, and how you want to play it.

Ok brother. Thank you so much for answering my stupid questions.

 

[ghamilton]

C51 52 has .47 50v caps in those places. These are not listed in the SM.
Could I put non-polar caps in there?