digital equipment corporation · maynard, massachusetts
Q2040 Disk Drive Repair

Quantum Q20x0 drive have a rubber bumper on the stop used to limit the head movement. The rubber in these drives has deteriorated and frequently prevents the heads from moving when the drive is powered on. Normally after the drive is up to speed the drive goes through a seek pattern to calibrate the drive servo. The heads can be freed by pulling up the yellow sticker near the heads and then pulling them to free them from the sticky rubber. This does not fix the deteriorated rubber so it will likely cause more problems. The data on the drive was recovered using my MFM reader/emulator. Another drive had unreadable tracks. I tried recovering the data by pulling the head servo but the data was erased so was unable to recover.

I was loaned two drives to work with. They had bearings that were too bad to try to run the drive. I quickly shut the drive down when the noise got to uncomfortable level. I opened up the motor and lubricated them. The spindle bearings were also very bad so I tried to lubricate them. See the pictures below. Removing the drive pulley with the drive upside down will cause damage. Also with the deteriorated rubber stop if too much offset voltage is applied to the servo loop the servo will go unstable and hit the stop. With the bad stop the heads will go too far towards the outside of the disk and cause damage. Hopefully I can use this drive to practice techniques to replace the bad bearings and head rubber bumper to repair the second drive. Just need to get the illusive free time. Spindle bearings are 6202 and motor bearings are 608Z

The following picture links also have descriptions of what is shown in the pictures.

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Gooey bumper ( 49K)  How to unstick ( 51K)  smeared ( 65K)  Another bumper ( 60K)
Spindle upper bearing ( 93K)  Spindle lower bearing (117K)  Platters ( 69K)

Feel free to contact me, David Gesswein djg@pdp8online.com with any questions, comments on the web site, or if you have related equipment, documentation, software etc. you are willing to part with.  I am interested in anything PDP-8 related, computers, peripherals used with them, DEC or third party, or documentation. 

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