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Where should the S/PDIF cable connect?
I have a fine little Gigabyte GA-G31M-ES2L micro-ATX mb that I'll be using
for a HTPC shortly. I'm just waiting for the HDMI graphics card to arrive. I'm reading from the graphics card manual that the S/PDIF cable, which is just two wires, gets connected to the graphics card and then gets connected to the mb. The graphics card is a GIGABYTE GV-N84S-512I, and it has a two pin cable connection for the S/PDIF output. http://www.newegg.com/Product/Produc...82E16814125289 However, the S/PDIF header on the mb actually has three pins: #1 (power), #2 (SPDIFO), #3 (GND). Am I correct in assuming that I will only connect the cable to pins #2 and #3? If that's right then what is the power pin for? If I'm wrong then I'd appreciate a better understanding of how to proceed. Thanks, -- Jan Alter |
#2
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Where should the S/PDIF cable connect?
Jan Alter wrote:
I have a fine little Gigabyte GA-G31M-ES2L micro-ATX mb that I'll be using for a HTPC shortly. I'm just waiting for the HDMI graphics card to arrive. I'm reading from the graphics card manual that the S/PDIF cable, which is just two wires, gets connected to the graphics card and then gets connected to the mb. The graphics card is a GIGABYTE GV-N84S-512I, and it has a two pin cable connection for the S/PDIF output. http://www.newegg.com/Product/Produc...82E16814125289 However, the S/PDIF header on the mb actually has three pins: #1 (power), #2 (SPDIFO), #3 (GND). Am I correct in assuming that I will only connect the cable to pins #2 and #3? If that's right then what is the power pin for? If I'm wrong then I'd appreciate a better understanding of how to proceed. Thanks, The provision of +5V, is if you wanted to connect a TOSLINK electro-optical module to SPDIF_out. (My motherboard that came with an adapter plate of that type, has a 1x4 pin connector on the end, and one pin is blocked so the connector only fits one way. The three remaining pins carry power, ground, SPDIF_out.) In your case, with a copper only connection, you would use pin 2 and 3, to run across to the video card. So contrary to what your manual is claiming (which would be appropriate if a three pin cable was being connected), you just want to connect to 2 and 3. What you want to make sure of, is that GND goes to GND. In the video card manual, the connector appears to be keyed, so you can probably only connect the cable that comes with the 8400GS, one way. The other end of the cable, should have a red and black wire as depicted. You'd want the black wire to go to ground on the motherboard, and that would be pin 3. So that looks like the black wire would be closest to the bottom edge of the motherboard. ftp://download.gigabyte.ru/manual/vg...84s-512i_e.pdf (p.8) ftp://download.gigabyte.ru/manual/mb...s2c)_2.x_e.pdf (p.28) ******* The signal coming from the motherboard, could be a logic level signal (as that would make it suitable for driving a TOSLINK optical transmitter). It wouldn't make sense to have a low amplitude AC signal on the SPDIFO. So you cannot connect a coax cable directly to the motherboard header, and run it to your AV receiver at some future date. It looks like that header is mostly intended for what you're doing with it now, running it across to the video card. For example, to convert from "motherboard" SPDIF to "AV receiver" SPDIF, my SPDIF adapter plate includes the following components. (The adapter plate fits on a PCI slot cover.) motherboard_SPDIF --+- capacitor ---- 384_ohm_resistor -----+-- RCA connector | | | 100 ohm | resistor +--- (to TOSLINK TX module) | logic level signal GND The parallel combination of 384 and 100, gives a Thevenin equivalent of 79.3 ohms (it is probably supposed to be 75 ohms). The attenuation is 100/(384+100) or about 0.2 of the original signal level. In order to get the 0.5V to 1.0V level defined here, the motherboard logic level would have to be anywhere from 2.5V to 5V in amplitude. The selection of resistors, is intended to help match a 75 ohm coax cable. http://en.wikipedia.org/wiki/Spdif HTH, Paul |
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Where should the S/PDIF cable connect?
"Paul" wrote in message ... Jan Alter wrote: I have a fine little Gigabyte GA-G31M-ES2L micro-ATX mb that I'll be using for a HTPC shortly. I'm just waiting for the HDMI graphics card to arrive. I'm reading from the graphics card manual that the S/PDIF cable, which is just two wires, gets connected to the graphics card and then gets connected to the mb. The graphics card is a GIGABYTE GV-N84S-512I, and it has a two pin cable connection for the S/PDIF output. http://www.newegg.com/Product/Produc...82E16814125289 However, the S/PDIF header on the mb actually has three pins: #1 (power), #2 (SPDIFO), #3 (GND). Am I correct in assuming that I will only connect the cable to pins #2 and #3? If that's right then what is the power pin for? If I'm wrong then I'd appreciate a better understanding of how to proceed. Thanks, The provision of +5V, is if you wanted to connect a TOSLINK electro-optical module to SPDIF_out. (My motherboard that came with an adapter plate of that type, has a 1x4 pin connector on the end, and one pin is blocked so the connector only fits one way. The three remaining pins carry power, ground, SPDIF_out.) In your case, with a copper only connection, you would use pin 2 and 3, to run across to the video card. So contrary to what your manual is claiming (which would be appropriate if a three pin cable was being connected), you just want to connect to 2 and 3. What you want to make sure of, is that GND goes to GND. In the video card manual, the connector appears to be keyed, so you can probably only connect the cable that comes with the 8400GS, one way. The other end of the cable, should have a red and black wire as depicted. You'd want the black wire to go to ground on the motherboard, and that would be pin 3. So that looks like the black wire would be closest to the bottom edge of the motherboard. ftp://download.gigabyte.ru/manual/vg...84s-512i_e.pdf (p.8) ftp://download.gigabyte.ru/manual/mb...s2c)_2.x_e.pdf (p.28) ******* The signal coming from the motherboard, could be a logic level signal (as that would make it suitable for driving a TOSLINK optical transmitter). It wouldn't make sense to have a low amplitude AC signal on the SPDIFO. So you cannot connect a coax cable directly to the motherboard header, and run it to your AV receiver at some future date. It looks like that header is mostly intended for what you're doing with it now, running it across to the video card. For example, to convert from "motherboard" SPDIF to "AV receiver" SPDIF, my SPDIF adapter plate includes the following components. (The adapter plate fits on a PCI slot cover.) motherboard_SPDIF --+- capacitor ---- 384_ohm_resistor -----+-- RCA connector | | | 100 ohm | resistor +--- (to TOSLINK TX module) | logic level signal GND The parallel combination of 384 and 100, gives a Thevenin equivalent of 79.3 ohms (it is probably supposed to be 75 ohms). The attenuation is 100/(384+100) or about 0.2 of the original signal level. In order to get the 0.5V to 1.0V level defined here, the motherboard logic level would have to be anywhere from 2.5V to 5V in amplitude. The selection of resistors, is intended to help match a 75 ohm coax cable. http://en.wikipedia.org/wiki/Spdif HTH, Paul Hi Paul, Thank you very much for providing a more than adequate explanation of the pin layout on the mb and TOSLINK possiblity. Your explanation both confirms and elucidates me to how to make the connection. It was also nice of you to be thorough and rummage through both the mb and graphics manuals to solidify the information that I asked. Actually you gave me a much better understanding to the point of the S/DIF usage and its potential. The cute thing about putting the HTPC is that I'm doing it all backwards. I don't even have a flat screen TV at this point,still watching on a CRT, and still looking at and comparing the 40" LCD models among the different brands, comparing the watts used and then noticing the newer LED technology; that it uses 30 to 40 % less power to run the TV, but then costs more than twice as much to purchase. I think I'm pretty lucky to have to think about such nonsense sometimes. -- Jan Alter |
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Where should the S/PDIF cable connect?
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#5
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Where should the S/PDIF cable connect?
"Jan Alter" wrote:
.... still looking at and comparing the 40" LCD models among the different brands, comparing the watts used and then noticing the newer LED technology; that it uses 30 to 40 % less power to run the TV, but then costs more than twice as much to purchase. I think I'm pretty lucky to have to think about such nonsense sometimes. like instead of figuring out the best place to live without being bombed... yup I think about that also when going to a megastore and looking for something that I have never needed or looked for before, and knowing that it will be there. |
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