Some drives have a rubber or soft plastic bump stop for the head actuator. If stored for a long period of time with the heads parked, the part of the actuator that touches the stop can get stuck to it - or the material the stop is made of can deteriorate and get sticky. Freezing the drive may harden the stop and if it causes enough differential shrinkage between the stop and what's stuck to it, it can pop loose. Some drives use a small magnet to hold the actuator parked, and if left there for a long time the steel piece on the actuator can become overly magnetized to where the attraction is too strong for the actuator to overcome to be able to move. This also happens a lot in CD and DVD drives left unused without a disc inserted for a very long time. They use a magnet on one side and a piece of steel on the other side of the disc clamp. Usually the magnet is on the spindle motor. Without a disc in, the clamp parts fit closer together and can develop an attraction too strong for the eject mechanism to separate unless there's a disc inserted to hold the clamp farther apart. For that problem in a hard drive, a small piece of aluminum foil flue tape stuck onto the non-moving side of the stop could keep it far enough apart to weaken the magnetic attraction. For optical drives I've super glued layers of thin cardboard onto the clamp hub so that when a disc is in the center of clamp and hub have a very tiny gap. Without a disc the clamp is kept far enough from the magnet that it can break the attraction. Even then, some clamps get too strongly magnetized. (A tape eraser might work to cure this. Take the cover off the drive and zap the clamp from both sides. I don't have a tape eraser.)
Hard drives and optical drives with the ability to develop this problem happened because the people who designed them either never envisioned them being left unused for years, or if they did consider this problem didn't figure it would/could ever happen. Who would never use a hard drive for a decade or never put a disk in a drive for years? Making the actuators and eject mechanisms strong enough to overcome the force of over-magnetized park and disc clamps would cost more - why bother doing that for a situation that would 'never happen'? Same thing with hard drives that don't hold the heads in park with a magnet. If they considered the performance of the bump stop material when something is pressed against it for years, they likely figured getting sticky was a non-issue because nobody would ever leave a drive parked and unused for a long time. -- -- ----- You received this message because you are a member of the Vintage Macs group. The list FAQ is at http://lowendmac.com/lists/vintagemacs.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To leave this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/vintage-macs Support for older Macs: http://lowendmac.com/services/ --- You received this message because you are subscribed to the Google Groups "Vintage Macs" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
