MacBook Pro: Buzz or whining with DVI devices (including projectors) -- fixes; Battery swelling; more
MacBook Pro: Buzz or whining with DVI devices (including projectors) -- fixes; Battery swelling; more
Buzz or whining with DVI devices (including projectors) -- fixes We continue to report on an issue where the MacBook Pro exhibits an irritating buzzing or whining noise that is transferred through connected speakers when a DVI device, such as an external display or an LCD projector, is connected.
The noise can generally be eliminated by disconnecting the DVI cable. It can also be worked around by using a professional audio capture/output device that attaches via FireWire or USB.
It also appears that increasing processor load (by running processor intensive applications) will increase the noise's volume.
The problem is most likely to occur when connecting the MacBook Pro to equipment with balanced inputs -- unbalanced input equipment will not usually exhibit the issue.
MacFixIt reader Mauricio Ardila reports that separating the audio signal ground from chassis ground will eliminate the whine for balanced equipment.
"The output of your MacBook Pro has three conductors... (stereo line-out) one carries the Left audio signal, one carries the Right audio signal, and one carries the audio signal ground. Usually you will connect a cable that splits into two, the Left and Right. That's the cable that you plug in your MacBook Pro and you plug on the other side to the left and right of your audio equipment, say an amplifier or amplified speakers, etc. The Left signal usually comes from the tip of the connector you introduce into the MacBook Pro, the Right signal comes from the "ring" in the middle, and the audio signal ground comes from the sleeve of the connector. On the other side, where it splits into two cables, the conductor with the left and right signal is wired appropriately (usually the tip) depending on the type of connector used (RCA, 1/4", 1/8"). The shield and/or audio signal ground is split in two.
"So you go from S(L - R - G) to S(L-G) on one cable and S(R-G) on another cable. S is the shield around (hence the parenthesis) the actual wires inside L, R, and G."
"If you connect your MacBook Pro to an unbalanced equipment, and the cable does not have the shield (S) connected to the audio signal ground conductor(G), you will probably have no problems, no noise. But if you connect your computer to a balanced equipment such as a professional pair of speakers with balanced inputs, then it matters how the cable is wired. Most standard cables, as I mentioned before, wire the shield to the audio signal ground(S-G), and usually this means you are connecting audio signal ground to chassis ground. What Apple suggests, is to disconnect the chassis ground from the audio signal ground.
"I am connecting my MacBook Pro to professional balanced inputs with XLR connectors or 1/4" TRS. This means I will have to "lift" (disconnect) the shield from audio signal ground . Because most cables available commercially tie the shield to the audio signal ground wire, I unsoldered pin 1 in the XLR connectors, completely removing the audio signal ground connection between my MacBook Pro and my speakers. The cable is now connecting my MacBook Pro to my speakers only through the L and R wires. The connection via the audio signal ground G and the shield S has been disconnected."
Battery swelling Meanwhile, we continue to receive reports of batteries swelling then becoming non-functional. Our own in-house MacBook Pro 1.83 GHz is awaiting a battery replacement, as its battery has swollen significantly, resulting in the system sporadically shutting down or failing to operate without AC power.
As previously noted, in most cases, Apple is replacing these defective batteries on an individual basis. The company has yet to disclose a manufacturing defect affecting any range of serial numbers or date-based production runs.
Anecdotal evidence (including our own in-house experience) suggests that the problem primarily affects MacBook Pros that were shipped early on in the production cycle -- our MacBook Pro was shipped in February.
MacFixIt reader Frank Bry is the first to report this issue with a 17" MacBook Pro:
"My 17" MacBook Pro (2.16 GHz) has a battery that has begun to swell noticeably. In the center front. The MacBook does get hot but the fans have never come on."
MacFixIt reader Tim adds:
"My battery is swelling, it last less then one hr and turns off the computer i need to plug in the AC to get it to start again. I ordered my MacBook Pro as soon as it was announced. Looking forward to a solution."
Finally, one reader writes:
"My machine runs on AC power 85% of the time, but last week I disconnected the power to move the computer and within 10 steps it shut off. That afternoon it got so bad I couldn't even start the machine on battery.
"The next day after I attempted troubleshooting myself I called Apple again. After I told them I had already reset the PRAM, reset the power manager and conditioned the battery just last week, they asked me to remove the battery and look at the edges. My edges were fine, but I read the post at MacFixIt and evidently Apple has too or this isn't the first time they have this problem. But my batter showed no outward signs of problems. I specifically asked and I was told both my computer and my battery serial numbers were in the "special" range and they sent me a new battery, which fixed the problem.
Now if they'd only fix the heat issue. I'd be satisfied with 162 degrees F. I've attached a screencap of my computer running at 81C (172F), and I've seen 84C (183F). Granted I'm cranking a iMovie at the time but come on. The FDA says that's a temperature high enough to cook ground beef and poultry to be safe."
Static from speakers: Using a USB mic We previously noted an issue where a slight static noise is audible from audio-out-connected headphones on some MacBook Pros.
For a temporary solution, some users have resorted to using USB-based audio output devices.
MacFixIt reader Perry Peterson writes:
"I have used a Griffin iMic for headphone use instead. The iMic is right in front of me on my desk, thus very handy, and the audio is crystal clear through my headphones. This may not be the ideal solution for a MacBook Pro, but it might help users 'get by' with headphones until a better fix comes along."
Feedback? Late-breakers@macfixit.com.
For further coverage, see our MacBook Pro special report.
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