VOGONS


First post, by FFXIhealer

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Ok, so new project time.

While I was working a few years back for an IT company (me and a boss...not exactly a company, really more of a tag-team), he was gonna throw out a couple of old Pentium 4 Windows XP machines that really didn't work worth a shit anymore. Well, the insides were gutted, but I kept the mid-tower Micro-ATX cases, one power supply, the optical drives, fans, etc. Later on, we had to replace someone's motherboard/CPU from a Dell Vostro 220 and I kept the MB and the RAM, as the CPU itself was the problem. He also had an old Pentium Dual-Core E2220 (2.4GHz Core-2 class Pentium processor) for socket 775, so I dropped it in and the system woke to life.

So this case has been sitting on my floor for a few years now and it has a valid Windows XP license key sticker on the side and I'm thinking hey...maybe this could be used for a cool XP retro gaming system if I ever manage to get a graphics card for it. The MB has a built-in graphics chip so I can set it up and everything. So I did. I pulled a used 80GB SATA hard drive and used the DVD-RW drive from one of the cases, hooked everything up and got it running. I did this only a few days ago.

Audio chip: Realtek ALC662

So the case is not the original DELL OEM case, so the front panel audio connectors use what APPEARS to be a standard '97AC audio connector, but when hooked up to the MB, there's something the MB has a problem with and I have to press F1 EVERY BOOT to continue. After installing the proper audio drivers in Windows XP, I tried some connection testing with the software window up (so I can see which "ports" are connected in real-time). I used a 3.5mm stereo audio cable and my digital multi-meter to trace the lines on the front panel jack. I also looked up the HD-AUDIO and AC'97 audio standard pinouts. Here's what I found:

AC'97
1- MIC: Front panel microphone input signal (biased when supporting stereo microphone)
2- AUD_GND: Ground used by analog audio circuits
3- MIC_BIAS: Microphone power / extra MIC input for stereo microphone support
4- AUD_GND: Ground used by analog audio circuits
5- FP_OUT_R: Right channel audio signal to front panel (headphone drive capable)
6- FP_RETURN_R: Right channel audio signal return from front panel (when headphones unplugged)
7- AUD_5V: Filtered +5V used by analog audio circuits
9- FP_OUT_L: Left channel audio signal to front panel (headphone drive capable)
10- FP_RETURN_L: Left channel audio signal return from front panel (when headphones unplugged)

So what I learned (and most of you probably already know), is that the old AC'97 standard had a pass-through for the front panel that when NOTHING was connected, the audio was sent BACK through into the header and that's how the rear audio was cut off when headphones were plugged into the front of the case. This is currently how the front panel is wired and works on the Compaq case. However, this is NOT how the Dell MB works. Let me show you...

HD-AUDIO
1- PORT 1L: Analog Port 1—left channel (Microphone)
2- GND: Ground
3- PORT 1R: Analog Port 1—right channel (Microphone)
4- PRESENCE#: Active low signal that signals BIOS that an Intel® HD Audio dongle is connected to the analog header.
5- PORT 2R: Analog Port 2—right channel (Headphone)
6- SENSE1_RETURN: Jack detection return for front panel (JACK1 - Pink)
7- SENSE_SEND: Jack detection sense line from the Intel® HD Audio CODEC jack detection resistor network
9- PORT 2L: Analog Port 2—left channel (Headphone)
10- SENSE2_RETURN: Jack detection return for front panel (JACK2 - Green)

When I short out pins 5-6, the software tells me a Microphone is connected. When I short out pins 9-10, it tells me headphones are connected. When I actually hook up headphones, I can hear audio from BOTH the back panel (on my TV monitor) and the headphones simultaneously. So I KNOW it's not wired up for AC'97 at the audio jack. But it's SUPPOSED to be able to do both - that's why there's pin 7, the HD Sensor line. I've read posts on the internet and I'm supposed to just be able to plug AC'97 directly into the port and it just work, but when I do, the software goes nuts and I see the headphones and microphone jacks constantly lighting up and down. And I STILL get the "Front Audio Cable Error - press F1 to Continue or F2 for Setup" shit during boot.

CABLE WIRES
So my cable from the front audio panel jacks has the following cable pins
1 - Microphone Tip: First microphone line from the stereo pin jack
2 - Common Ground: All grounds are wired together to this one pin
3 - Microphone Collar: Second microphone line from the stereo pin jack
4 - Microphone Collar Return: When nothing plugged in, pins 3 and 4 are connected and have continuity between them
5 - Headphones Collar: This is audio out on the Right channel.
6 - Line-Out Return: When nothing plugged in, pins 5 and 6 are connected and have continuity between them.
9 - Headphones Tip: This is audio out on the Left channel.
10 - Line-Out Return: When nothing plugged in, pins 9 and 10 are connected and have continuity between them.

If this is AC'97, why is there a microphone return lead? What does it do? If nothing's plugged into the microphone jack, what is pin 3 supposed to be doing? Right now, I have it set to Pin 4 on the MB, but since the port is HD-AUDIO, I don't know what to do here. Should I move the pin to 7 instead? You see my problem here.

So either I figure out how to make the shit work so the error goes away with some clever wiring...or I DISABLE the on-board audio chip and use an actual sound card. I DO have 2 PCI slots available. I'm just having trouble finding a good PCI sound card that also has front-panel audio connectors on it. It would also be nice if it supported EAX, like the Sound Blaster cards did. I GUESS I could use the PCI-Express 1x slot and use a more modern card. In fact, I have an X-Fi Titanium Fatality card lying around in a box somewhere I could use...

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Reply 1 of 7, by gdjacobs

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I use this pattern for HDA capable boards in AC'97 cases. Essentially, you lose the sense return lines and disable jack sensing in software.

All hail the Great Capacitor Brand Finder

Reply 2 of 7, by FFXIhealer

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The way I have it wired now, I moved that Mic return line to the black (8) pin, the one that is blocked off, so it's not currently being used. I still get that F1 to continue message at POST, though.

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Reply 3 of 7, by gdjacobs

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Do you get the message when no audio header is plugged in at all? Maybe some of the sense pins need to be strapped by a resistor to satisfy the Dell firmware?

All hail the Great Capacitor Brand Finder

Reply 4 of 7, by FFXIhealer

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Yeah, I get the message with nothing installed. I wonder if it really wants HD audio before it’s satisfied.

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Reply 7 of 7, by FFXIhealer

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Researched more, it expects a 1,000 ohm resistor to ground. But then the jack sense lines are also wired totally differently. in HD Audio, Pin 7 is the SEND for the jack sense lines. The two jacks have different resistors before going to their respective pins (6 and 10). So no, I can't re-wire it.

But what I did do was hook up an HD Audio cable from a totally different case (two computers sitting next to each other like a baby with an umbilical cord) and the F1 error went away.

Ok, so new plan. This is what I pulled out of the case:

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And this is what I found on-line:
http://www.caselabs-store.com/bullet-usb-3-0- … ront-panel-i-o/

I'm thinking, that Caselabs item looks like I can take it apart as well and use the two audio jacks separately from the USB 3.0 jack. Plus, I might be able to fit that USB 3.0 jack into a different case to replace its USB 2.0 front panel ports. I also think I can carefully cut the pink and green rings around the audio jacks on the old computer and glue them onto the HD Audio ports around the jacks there, keeping the color scheme going.

So yeah, I think this thread just turned into CASE MODDING. So exciting...

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