Matrox, a liar? [NOT my comment, but the site's]

[conanian]

http://www.darkcorw.co.kr

The low-pass filter on the P prototype:


The low-pass filter appeared on P-cards sold to Korea:


It seemed that capacitors are used in place of inductors...

[CaineTanathos]

and what difference does it make ?

[Inray]

Cheap alternative solution

[CaineTanathos]

so no real difference in quality

[GT98]

Prototype Thats the key word...so is Matrox a liar for putting on a smaller heatsink on Retail models vs the Prototype photos we saw before the P came out?

[dZeus]

if the retail version doesn't contain the filters as according to the docs (which seems to be the question?), then I can't blame the site linked for claiming Matrox lies in those docs.

Question of course is wether those filters are really different from the specifications in the docs, as different to the prototype doesn't mean much (as pointed out already).

[R.Carter]

Well, I fail to see how they jump to conclusion that since the components are not visually identical between the prototype and the retail that they have changed anything.

Typically surface mount capacitors are shades of brown. The components in question appear to be white and look identical to the other inductors that appear on the prototype board.

I somehow doubt that they are capacitors.

Did the author of this article go through the effort of actually remove these components and measuring their values? If not I have to say that simply going by visual appearance doesn't tell you a whole lot in most cases.

[conanian]

Originally posted by dZeus
if the retail version doesn't contain the filters as according to the docs (which seems to be the question?), then I can't blame the site linked for claiming Matrox lies in those docs.

FYI: The filter as on the docs (Still hosted on that site.)

The components where most of the question is is the change of some of the inductors (The three vertical ones on the right) were definitively changed into capicitors...

However, according the comments on a Chinese site: the white caps used are actually very high-graded for this use..

[CaineTanathos]

so no quality loss

[afterburn]

Look at the pictures: mid, left side you see this black thingie, designated R851 a resistor
Below that, is a brownish thingie, designated C809, a capacitor.
Below that, are the rows of white components. There is no space for designations there, but if you look at the row below those, which are 90 degrees rotated to the first, you see they go with the first with designation L616, which is an inductor.
Now if that is not enough, filters using capacitors are wired fundamentally different than filters using inductors. You cannot just simply exchange the two, and expect it to work: a capacitor gets a higher impedance as frequency drops, whereas an inductor gets a higher impedance when frequency rises. To put it simple, they behave as electrical opposites.

This whole thing is stupidity of the site and basically showing they have no clue as to what they are talkign about.

EDIT: the only real difference between the two is the absence of capacitors C808, C801 and C795.
The inductors that mistaken for caps are: L613, L615 and L617.

[R.Carter]

conanian,

Well, as far as I can tell, the three vertical inductors on the right (L610, L611 and L612) were not changed into capacitors on the retail board. The components on the retail board are white which appear to be inductors.

Capacitors are brown.


afterburn,

Yeah, I just noticed the three missing capacitors C808, C801, C795 on the retail board. Strange, it looks almost as if someone removed them based on the solder on the pads.

[Marshmallowman]

whats the problem?

equivalent filter circuits can made with either components, a fifth order filter is a fifth order filter whether you use inductors,capictors or a combination of both..

Is there any diference in the filtered ouput?...or is the final board better than the orig?

[SteveC]

afterburn - exactly what I was thinking - an inductor and capacitor can;t simply be swapped over!

[GNEP]

Am I being silly here or could the ones on the alpha boards be the same components (well, packaging at least), with some extra copper wound round for fine adjustments during the testing process? Then the real ones used in the production boards have the correct (adjusted) inductance to start with therefore need no extra copper wrapped around?

gnep

[afterburn]

Could very well be.