hp-9121 floppy disk repair help needed


I have one hp-9121 hp-ib floppy disk unit and one of the floppies does not work: when I insert a floppy it does not stay inside (no lock). I guess it would need some cleaning inside, can anyone give me some guidance for that ?

First of all how can I open the case without damaging the system, are there any precautions to take ?

What method should I use for cleaning the mechanism ?

Thanks in advance for your help.



This sounds like dried and hardened grease on the eject mechanism. It's a very common problem with the full-height Sony 3.5" drives. At least yours is a single-sided drive, so there's no risk of head damage from this -- in the double sided models it's possible for the upper head to get caught in the disk when you eject it, and for the head then to be ripped off the gimbal spring.

Anyway, I wrote an article in Datafile (HPCC journal) last year about how to take the (double-head) drive apart and clean it, with a follow-up article a couple of months later on a newer type of eject mechanism that I'd seen. I suspect that, being a single-head drive, you'll have the older type. It's not hard to take it all apart and clean it, but there are a lot of little parts and if you've not done it before you might find the articles of use.

I would think HPCC could sell you back issues of the appropriate issue(s) of Datafile.



Thanks Tony for your input. Can you tell me if it's possible to do some basic cleaning without taking everything apart ? How can I safely open the case and where should I first look for ?

I would like to try this first before and it doesn't work I will investigate further with the Datafile article.

Thanks in advance,



I've never tried to clean one without fully dismantling it. I guess I had a misspend childhood (:-)), I rebuilt my first ASR33 while still at school without the manuals (and that thing has over 1000 parts), so taking a disk drive apart doesn't bother me. If you follow the article you'll not upset the head alignment (don't remove the stepper motor or track 0 sensor), so you don't need the alignment stuff.

As regards getting inside a 9121. Unplug all the cables from the back, then either push the power switch in (as if to turn it on), or pull the button off. Then remove the 2 screws from the back, and lift the back edge of the plastic cover up. It'll 'hinge' on the bottom front of the bezel and will then come off. Note how the tabs hook over the front of the metal chassis.

There's a plastic cable guide post in the middle of the chassis, held on by one screw. Take that out next. Then remove the 3 screws holding each drive in place, lift the drives out and unplug the cables.


Hi Tony,
Thanks for your advice, I'm more on the software side of life, so totally dismantling a disk drive seems a little scary to me... I will open it and see if I can easily unblock the mechanism.
best regards,


Hello Tony,

Following your instruction, I was able to clean the external mechanism and this was enough to make it work again !

Thanks for your support !


Possibly Related Threads...
Thread Author Replies Views Last Post
  [OT?]Orthography corrector needed. Diego Diaz 8 2,033 06-22-2013, 04:31 PM
Last Post: Andrew Nikitin
  HP 9885M disk drive David Ramsey 0 814 05-12-2013, 09:38 PM
Last Post: David Ramsey
  Alignment disk and procedure for 9114A aj04062 1 941 03-28-2013, 04:54 AM
Last Post: Tony Duell
  No luck getting flash disk to work in 95lx Harald 7 2,479 03-18-2013, 08:11 AM
Last Post: Harald
  HP-50g How to store many equations - help needed Timo Labrenz 5 1,672 03-03-2013, 12:22 PM
Last Post: Timo Labrenz
  Updated PPC DVD Disk w/HHC2012 Materials Jake Schwartz 1 1,014 01-26-2013, 02:45 AM
Last Post: Walter B
  Disaster: help for a couple of HP97 needed! Jose Gonzalez Divasson 10 2,361 01-21-2013, 04:45 PM
Last Post: aurelio
  HP41 emulator for HP48sx - keyboard overlay needed Doug (NYC) 3 1,241 12-31-2012, 03:11 PM
Last Post: Allen
  restoring HP29C - help needed Alberto Fenini 9 1,927 11-25-2012, 07:56 AM
Last Post: Alberto Fenini
  HP 34 and HP 41 Repairs Needed matthewx 4 1,460 07-16-2012, 09:12 PM
Last Post: matthewx

Forum Jump: