The schematic shows them as 1µF 50V, there is not much point upgrading these to film capacitors as they are not in the signal path, being as they are, part of the protection circuitry.
AU-D907 LIMITED vs 919
- Thread starter ghamilton
- Start date
ghamilton
Super Member
My SM on board 2839 does not list these caps. Are you sure?
C51 C52
GrisPato
Super Member
They are in the schematic not in the parts list of the board. These lists are never complete the schematic most often is.
PS
Nice exception to that rule is in this SM. C45-46 are in the boards list but not in the schematic.
ghamilton
Super Member
Thanks but what value should I put in there? The factory put .47uf in those places and I want a low esr cap there.
GrisPato
Super Member
As Hyperion said, they are just there in the protection circuit part that resides on the driver board. If they are still the original electrolytic capacitor then you could change them with a 1 uF-50V electrolytic or a 1uF film capacitor. Just for longlivety, no sound improvements.
ghamilton
Super Member
Are non-polar ok?
JoseHH
Super Member
Probably not.
Non polar (or bipolar) electrolytic capacitors will most likely have higher ESR than an equivalent capacity polarized capacitor like the nichicon UPA or even the UPW. If you want you could put 0.47uF films there, but I see no real need for this.
ghamilton
Super Member
Ok thanks, Now for C19 20 45 46.
I noticed that Leestereo went from 3.3 to 47.uf. That's a big jump! How about 4.7uf?
ghamilton
Super Member
Then what exactly would you put in there?
ghamilton
Super Member
They will stay then.
Now what about C19 20 45 46?
I am looking for a low esr for this. Can't find it. What would you put in those places?
To avoid all these '200 Capacitor Questions or Bust' - why don't you follow Leestereo's choices to the letter? - he gives the value/voltage and exact type (often giving the 'why' as well), of each component in his excellently documented restores.
kevzep
Its all about the Music
What do you mean "seems a bit high", what is your theory based on?
Absolutely not, why? because that represents a value reduction from 3.3µF = Sansui's standard to 0.47µF Your standard. I see now that 0.47µF might be a typo for 4.7µF, a value increase by that much is hardly worth the effort. I have used Leestereo's recommendation for these capacitors, i.e 47µF 63V on my own AU-919, and one other AU-919 restore without any problems. They are there for (very) local filtering of the supply lines to the power amp, so the value increase - which is actually quite modest, is perfectly fine.
GrisPato
Super Member
Ok, didn't think about that. Would that matter a lot in this functionality?
A 0.47uF electrolytic will have an esr around 2-3 ohm already, a bi-polar 1 uF? maybe 3-4 ohm? Of course you're right that there is no benefit using a bi-polar.
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GrisPato
Super Member
This is something I still am not sure about, there function. On the schematic of the AU-819 they are placed between positive and negative rail. So if they filter, where to does it go? ( the filtered frequencies)
