Re: Sansui TU-9900 Resistors upgrade


Radu Bogdan Dicher
 

John,
I second your choice of Vishay CMF/RN resistors. Have not tried the Beyschlags, though from a quick glance over at Mouser, they seem extremely inexpensive, even in high precision flavor. 

Technically, it seems the RN/RL is the mil-spec version of the CMF (which is "global/industrial" type), though I agree - they're likely the exact same resistor inside with different scribbles on them. When "mil-spec'd," they seem to derate them to lower handled power at a given temperature (though not on the same sheet, so I'm not very sure what that's about). 

I did notice though, at least at Mouser, I tend to find the RN cheaper than the CMF for a given value. They have the added nuisance of the weird value markings, but once you get used to the aspect, no biggie. The CMFs typically have very normal, spelled out values with no coding whatsoever, so that's just a bit easier on the eyes. 

I personally prefer any alphanumeric markings to color coding any day of the week. 

Radu.  

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On Mon, May 3, 2021 at 5:57 PM John Carpanini <jacarp@...> wrote:
Hi NounoursX2,

 The salient point of the observation was that IMO & based on having done 3 9900s the OEM resistors were all to often out of spec.  The power supply was particularly problematic, heat maybe??.  The KOA SPR series work very well in that application, are very quiet and were designed to be used in a power circuit.  The fact that they are also pretty good in the signal path was just the cherry on top.

When using metal films, & given my druthers i try to use the Vishay/Dale CMF series in the signal path. These are literally MilSpec parts without the MilSpec markings.  Lately I've been playing with the Vishay Beyschlag  MBA/SMA 0204, MBB/SMA 0207, MBE/SMA 0414 - Professional series which seem quite nice. I feel that there is a slight difference in SQ between the CF & MF resistors.

If you want to see some pictures, Look here:

https://groups.io/g/FMtuners/photosearch?p=created%2C%2C%2C20%2C2%2C0%2C0&q=tu+9900

There's some good shots of the PS and the rest of the boards.  Have Fun,

Regards
JohnC

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