VOGONS


SBPro1 CT1330A, lets solve the Reversed Stereo myth!

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Reply 100 of 106, by CkRtech

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Creative is known for not following the datasheets. That was basically what I meant by their “design.” 😀

Hope the caps get it restored! I’m fairly certain they will.

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Reply 101 of 106, by carlostex

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Well i checked the TEA2025 datasheet and they did follow the datasheet for the most important part.

Anyway, card is now fixed, but here's the story:

I started by desoldering the 16V 470uf caps, that didn't look too good nor were looking very nice. Rubycon capacitors, so at least Creative didn't cheap out on the caps, at least if those were original, but soon enough i saw the disaster: both caps were leaking and the acid was already corroding one trace badly. Used the multimeter to check for continuity and that confirmed the trace was eaten. Willing to bet that trace was indeed the output trace for the right channel i got some white vinegar and a cotton bud to neutralize and get all that gunk cleaned. So some elbow grease, i exposed the copper on the trace and solder a wire between it and another healthy point. Turns out i didn't have replacement 16V 470uf capacitors only 330uf ones, but i soldered them on anyway. I got the card on the system, fired a game and soon enough all channels are now playing fine. Tried a game with support for stereo OPL2 and i could confirm both channels play and there is stereo separation.

I already ordered some replacement Panasonic FC's with 470uf for piece of mind.

Moral of the story: it doesn't hurt to check your vintage cards.

Reply 102 of 106, by CkRtech

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Thumbs up.

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Reply 103 of 106, by Jepael

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CkRtech wrote:

Creative is known for not following the datasheets. That was basically what I meant by their “design.” 😀

That's not really how it works. Datasheet examples are really just examples how to do it in one example application, not the only right way, and clearly the component values can be altered within limits to make it suitable in another application.

Would you care to say which particular part of their "design" you are referring to?

Reply 104 of 106, by CkRtech

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It was a shortened phrasing as I was replying on my phone at the time. I apologize for any confusion. Creative doesn't always follow datasheet implementations verbatim, and the datasheets by design show a possible implementation & will also go into calculations depending on which components you choose.

I believe we are basically in agreement here, but I'll elaborate a bit for kicks.

Basically a datasheet will recommend a value for a support component - like a capacitor value of say - 1000uf - for an implementation of a particular IC. Creative Labs might build their soundcard and use something like 680uf. Some people might read the datasheet, see the 1000uf component listed, and figure that Creative cheaped out on what component should be used. I think there was a thread on vogons that discussed it a bit for some people that were recapping SB16s and finding what they might consider a discrepancy between datasheet and Creative's implementation. I don't have a link to the thread handy, but that might provide an example of non-verbatim implementation.

Like you said - datasheets provide example implementations. In the case of this particular sound card and the amp that it used, 470uf is mentioned in the Stereo Application schematic. I didn't have an actual card in my hand to check the output caps for the amplifier - the datasheet specified 470uf, but that wasn't necessarily what Creative used in the circuit.

So when carlostex mentioned he went to the datasheet for the capacitor values, I just wanted to point out that Creative may have used something different from the illustrated application circuit possibility. Again, I didn't know which capacitors they used in the circuit as I didn't have a card. The datasheet itself makes note of the low cutoff frequency calculation due to the output capacitor for the amp:

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"It might change the sound, but the design wasn't Creative Labs decision" - well, it was Creative's design because they made the card and chose the caps they wanted to use for the circuit. Those caps could have differed from the datasheet, but in this particular case did not - as he pointed out in the next phrase stating that Creative just used the values they recommended.

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Reply 105 of 106, by Jepael

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Well you replied exactly what I would have said if I had made a longer post 😀 So yes, we agree completely.

I also recall that the general mantra that keeps repeating is that they put smaller caps to make cheaper products and I also think it comes from the fact that they really did put smaller caps there (but for a reason) and somebody just looks at the datasheet and says the caps are smaller than what they are supposed to be, which is of course not the case.

So I think the next time this comes up, I think I might ask that person if the installed caps are good enough and if the datasheet values are overkill for the environment the card is being used 😀 I mean, most unpowered 4-ohm desktop speakers are not large enough to produce 80 Hz, and most 8 ohm bookshelf speakers are not large enough to produce 40 Hz, and with 16-ohm headphones you approach the 20 Hz limit of human hearing, so there really is a bit headroom that allows for smaller valued caps.

Reply 106 of 106, by shamino

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Jepael wrote:

Well you replied exactly what I would have said if I had made a longer post 😀 So yes, we agree completely.

I also recall that the general mantra that keeps repeating is that they put smaller caps to make cheaper products and I also think it comes from the fact that they really did put smaller caps there (but for a reason) and somebody just looks at the datasheet and says the caps are smaller than what they are supposed to be, which is of course not the case.

So I think the next time this comes up, I think I might ask that person if the installed caps are good enough and if the datasheet values are overkill for the environment the card is being used 😀 I mean, most unpowered 4-ohm desktop speakers are not large enough to produce 80 Hz, and most 8 ohm bookshelf speakers are not large enough to produce 40 Hz, and with 16-ohm headphones you approach the 20 Hz limit of human hearing, so there really is a bit headroom that allows for smaller valued caps.

Creative's choices may well have been fine. But were they ideal? That's the part I think is in question.

From our point of view, it's not really a question of whether the originals were adequate, but whether some alternate set of values might possibly be more ideal. If those alternate values add another $1-$2 to the parts cost and are just slightly preferable, we'd probably go for that option, even if Creative wouldn't have.
However, lacking certainty on this, using Creative's original values is the safe way to go.