So you wanna fly out of the desert on a modified hard drive? Only in Hollywood!
Those indeed are two vendors of motor control chips, but there are many others and many variants. The newer ones may have internal current sense resistors and computer programmable current limits. I must point out that if you are crazy enough to try component level repair on an obsolete drive without schematics or code listings, you might consider coming to Silicon Valley where they pay you to do that kind of crazy, and you have access to both the schematics, PC board artwork/netlist, and controller code, and also more test equipment than you can fully understand in your life.
If you like, try visiting a great reverse engineering assistance site, http://www.plasma-online.de/index.html?content=http%3A//www.plasma-online.de/english/identify/picture/index_logochip.html
and see if you can identify the manufacturers of chips that you think could be the brushless spindle motor controller/driver and the voice coil driver from the chip logos. Then by reading the datasheet and application notes, you might get some ideas on overriding normal operation and manually ramping up the spindle rpms. On my 1993 vintage Conner 540 MB drive for example there is a row of SMT power transistors, and two nearby Silicon Systems LSI chips that are the likely suspects.
As a wild guess on non-electronic causes, I think over time the degraded lubricant along with abraded media from the head parking zone could plate out on the spindle bearing races and gradually contaminate them. It's a uncertain race between the bearings getting tighter from deposits and abrasion loosening the bearings with wear particles getting pushed to the side by the balls. The guys that know which happens first are not talking, and perhaps this is the kind of thing that varies greatly on whether the power is left on all the time, or if there are many power up/down cycles with consequent head contact in the parking zone.
Those indeed are two vendors of motor control chips, but there are many others and many variants. The newer ones may have internal current sense resistors and computer programmable current limits. I must point out that if you are crazy enough to try component level repair on an obsolete drive without schematics or code listings, you might consider coming to Silicon Valley where they pay you to do that kind of crazy, and you have access to both the schematics, PC board artwork/netlist, and controller code, and also more test equipment than you can fully understand in your life.
If you like, try visiting a great reverse engineering assistance site, http://www.plasma-online.de/index.html?content=http%3A//www.plasma-online.de/english/identify/picture/index_logochip.html
and see if you can identify the manufacturers of chips that you think could be the brushless spindle motor controller/driver and the voice coil driver from the chip logos. Then by reading the datasheet and application notes, you might get some ideas on overriding normal operation and manually ramping up the spindle rpms. On my 1993 vintage Conner 540 MB drive for example there is a row of SMT power transistors, and two nearby Silicon Systems LSI chips that are the likely suspects.
As a wild guess on non-electronic causes, I think over time the degraded lubricant along with abraded media from the head parking zone could plate out on the spindle bearing races and gradually contaminate them. It's a uncertain race between the bearings getting tighter from deposits and abrasion loosening the bearings with wear particles getting pushed to the side by the balls. The guys that know which happens first are not talking, and perhaps this is the kind of thing that varies greatly on whether the power is left on all the time, or if there are many power up/down cycles with consequent head contact in the parking zone.