PATA/IDE Jumper configuration

Question

PATA/IDE Jumper configuration

I recently bought an iMac G4 Flat Panel ("Snowball") 1.25 GHz, Model M9168LL/A, with 756 MB RAM, a 160 GB HDD and a non-working optical drive.

the previous owner did intend to replace the optical drive and had already gotten a replacement, but didn't get around to installing that before he decided to sell the machine, which came in nicely for me since I figured the upgrade should be fairly doable and I could directly upgrade the RAM while I had it open.

as I always do I did give it a test-run before working on it, and the machine worked as expected (that is everything but the optical drive worked).

I'm now working on it, and I have ran into one little issue, everything I can find about replacing the optical drive in these machines tells you to configure the jumpers the same as the drive you are replacing.

sounds sensible, but I don't think it will work this time, because that original drive is working just fine on a USB/ATAPI adapter.

the iMac didn't see the drive at all, but I was able to install an Microsoft Windows 10 Tech Preview into a virtual Machine on my PC using that drive and the USB adapter.

(VM Config: CD/DVD -> Connection -> Use Physical drive "G:")

so, if it didn't find it, the current settings are probably not right, I know the USB adapter is flexible about it, but from what I can find these iMac's are not.

the drive is on Cable Select now, but does anyone know what it should be?

a second issue I have because of this, is cleaning the old thermal paste off the heat-sink, as I have to apply new paste, and I have some (Arctic MX4), but I can't get the old stuff off, so far I can only come up with scraping it off, but I'm somewhat worried about possibly scratching the metal itself, which could affect the system's cooling performance.

Posted on Jun 18, 2015 12:13 PM

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Answer 1

Jeff

Level 6

12,058 points

Jun 18, 2015 8:18 PM in response to foxofinfinety

Since the hard drive and optical drive share the same ribbon cable, you can always take your cue from the hard drive's configuration jumper setting. If it's set to CS, set the optical drive to CS. If it's set to "Master," set the optical drive to "Slave." For systems that support it, Cable Select is a system builder's shortcut, enabling all drives to be configured the same, regardless of where the drive will ultimately be connected to the ribbon cable. You can still use a Master-Slave configuration on systems supporting CS, but it's just easier to use the latter. Apple didn't recommend using a liquid cleaner to remove the old thermal paste, but indicated using a plastic stylus or spatula - for removing the old and spreading the new compound. If you have an old credit card or similar stiff plastic item, you could trim it to an appropriate width and use it to scrape off the old residue. I never had a problem carefully using a Q-Tip dipped in alcohol, to remove old thermal paste residue from CPUs or aluminum heatsinks. I blotted the excess alcohol from the swab before cleaning, so that downward pressure didn't squeeze it all over the place.

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Answer 2

Jun 20, 2015 5:15 AM in response to Jeff

they don't share the cable, the drives both have their own cable, the earlier models, like the 700 MHz used a single cable, but the 1.24 GHz models use a short cable for the hard drive and a longer cable for the optical drive.

the cable for the hard drive just goes down from the drive to an IDE port labeled "hard drive", the cable for the optical drive initially folds under the drive to the front of the machine, and then at around halfway under the drive folds over to the right hand side to plug into the second, unlabeled, IDE port.

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Answer 3

Jeff

Level 6

12,058 points

Jun 20, 2015 8:38 AM in response to foxofinfinety

Even with the second revision motherboard having dual IDE buses, follow the same configuration setting that was applied to the hard drive (since it's the only device on that bus). You shouldn't have a problem with that setup. Also, check for adequate clearance for the optical drive tray's front trim piece and remove if necessary.

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