9114 disc drive issues

[John Garza (3665)]

I don't see much around here for the 9114. But I have one (not an A or B, just 9114) and I've tried it with a 41 and 71 and both report medium errors during the initialize/formatting process. At first I thought bad diskettes as these were salvaged from my old stock from in the 90's. But.. they all pass FORMAT and CHKDSK on a PS/2. 720Ks as HD diskettes don't seem to work at all in the 9114.

What I've done so far - from the ground up....
* replaced the battery and charged it
* fixed a mechanical issue with the diskette seating/ejecting
* cleaned the heads with alcohol
* lubed the rail and worm gear
* run the initialize with the top off - I can see the heads move across the surface of the disk.

Any ideas? Or is there a repair guide for these things?

Thanks!

-John

[35/45/55/80/70/65/67/67T/97/97S/91/92/21/22/27/25C/29C/19C/10/
31E/32E/33C/34C/37E/38C/41CX/71B/28S/19B/12C/15C/33S/35S/32S/
48GX/50G/Prime/DM42]

[BobVA]

- Do you have a good battery installed? (just the AC adapter won't work and a weak battery will cause all kinds of issues).

- As you note, you need to use 720k (non HD) media.

- If the eject wasn't working properly there may be damage to the head (as I recall the head could get hung up on the disk shutter?)

- There is a small repair guide

Bob

[John Garza (3665)]

New battery, charged overnight with a spare Topcat charger. Not running with the unit plugged in. Battery power only.

Most of the things in the repair guide I've already done. They just seemed obvious. A little penetrating oil cleared up the gummy old lubricant.

The heads look good. They don't look bent or loose. The top one is on a springy 'floating' platform, but I think that's normal. Watching the mechanism as I insert a diskette, the head seems to land gently on the surface of the disk.

The error message I get is towards the end of the process - the head goes back and forth a few times then back to the outer rim and starts stepping in a track at a time. It does that until the head is at or very nearly at the end - then the error message. If the head was dead I'd think it would error before that. But I could be wrong.

-John

[Martin Hepperle]

You might also want to check the track 0 sensor.
Sometimes dust and fluff collects in the gap, blocking the light beam.
Cleaning with some tissue soaked in alcohol should do it.

Martin

[John Garza (3665)]

The track 0 sensor looked clean.
But nevertheless, I cleaned it with a flattened Q-tip wetted with alcohol, then compressed air.

It seems to have made it worse. It errors after only the first 2 tracks or so.
It likely was not the culprit originally since this sensor detects if the head is on the outer edge of the diskette and I never had any problems there. But it may be evidence there was some dust in there and I just pushed it in a little deeper!
Time for some magnification work...

-J

[cruff]

You might try a bench power supply in place of the battery. I had a two year old battery that would no longer turn the disk spindle.

[John Garza (3665)]

Brand new battery ordered from Amazon. Disk spins fine and head moves back and forth.

I'm thinking I may have made it worse by cleaning the sensor.
Before, the head stepped across all tracks before it gave an error.
Now, it errors on the first one.

Not sure if the sensor is completely sealed or not.
Maybe a drop of alcohol seeped in.
I'll leave it with the top off for few days to allow it to evaporate.

-J

[Dave Frederickson]

(03-31-2023 01:26 AM)John Garza (3665) Wrote:  Any ideas? Or is there a repair guide for these things?

There's the CE Handbook. http://www.hpmuseum.net/document.php?hwfile=2716

Refer to Section V for running the built-in diagnostic self tests.

(03-31-2023 02:18 AM)BobVA Wrote:  - There is a small repair guide

Also, PeterP's repair manual. https://www.hpmuseum.org/guest/peterp/9114repm.pdf

[Hiwi]

Hi,
i like to share my hardware repair experience. I had 2 issues:

1. The print fuse in the battery case was blown. The drive was completly dead. Connecting a current limiting power supply showed, that there must be a short an the main board.
The 9114 powersupply generates the 12 V for the floppydisk using a pwm. The output drives a Mostfet. It had a short between drain and source. Replacing it (BUZ71) and the disk was working again.

2. Last week, the drive lids up all leds including test, but no spinning of the floppy. The 12V is there VC (5V) and 5V as well. But no 12V on the connector of the floppy. I tested the powerswitiching transistor, everything ok. No activity of the drive controller. The eprom was a bit hot, that was suspect. Signals oK, I tried to read it with epromburner, no error, but no content everything zero. It is an Intel 27128 Eprom. I had only 27C512 on hand, so with a minor change i should work. I burned the Code into the 27C512 and took pin 1 and 17 out of the socket and connected them to ground, pin 14. They are A14 & A15 and not needed.

To my suprise the drive came back to life.

I never had a faulty eprom before.

May be there is a design issue, the VPP line of the 27128 is connected to VCC. Should this not be ground? Actually reprogramming is not possible.



Ralf

   
I have attached the rom file, in case anyone else has the same issue.


  hp9114b.TXT (Size: 16 KB / Downloads: 10)

[brouhaha]

"Just a 9114" is a 9114A.

If you have it apart, I'm inter3sted in what HP part number is on the EPROM. Thanks!

[toml_12953]

Silly question here but what bit do I need to unscrew the screws holding the 9114 drive together?
Are they Torx (star) screws? If so, are they security screws? What size? I've tried T3, 4, 5, 6, 10 with no luck but maybe my bits aren't reaching the bottom of the recess.
This is driving me crazy!
Also, I have a replacement drive ready for when I can open the drive but it doesn't hold a disk in it. The disk just springs right back out. Is power required for the disk mechanism? I've only dealt with mechanical systems before.

[Dave Frederickson]

(05-24-2024 06:25 PM)toml_12953 Wrote:  Silly question here but what bit do I need to unscrew the screws holding the 9114 drive together?
Are they Torx (star) screws? If so, are they security screws? What size? I've tried T3, 4, 5, 6, 10 with no luck but maybe my bits aren't reaching the bottom of the recess.

They're T9 without security.

See the other service manual.
http://www.hpmuseum.net/document.php?hwfile=5063

[rprosperi]

Tom,

The drive in your 9114 probably is actually OK. The mechanisms on the drive for retaining and ejecting the media get "gunked-up" and the old grease & dust dry out to form stiff, sticky junk that prevents the mechanism from working properly. Once the case is open, carefully remove the drive and then clean the mechanism arms, slots and pivots using alcohol and Q-tips and it will probably be OK. Once clean and things move freely, add a tiny bit of lubrication (I use sewing machine oil) to the places where arms/pivots meet and using a sacrificial (bad) diskette, simply work it in/out many times and the action will become smooth and reliable. I've 'revived' 4-5 drives at this point, all seemingly broken (disk will not stay inserted) at the start.

That said, it's also possible that someone manually forced a stuck diskette out by grabbing with pliers and yanking, and this almost always damages the magnetic read/write head, which of course is in contact with the media when fully inserted. You just wont know until you get to the drive.

And note that HD media (2MB but commonly called 1.4MB) will NOT work.

Holler with issues or questions.

[Hiwi]

(05-24-2024 05:31 PM)brouhaha Wrote:  "Just a 9114" is a 9114A.

If you have it apart, I'm inter3sted in what HP part number is on the EPROM. Thanks!

Sorry, there was no label on my Eprom it is not a special HP part just an Intel 27128 Eprom.
I did not find any details in the service manual. There are no serviceable parts on the pcb.
They exchange the whole pcb and the drive I think

I have 2 9114B and both have no problem to read / write / initialize HD disks!

That is only true for the 9114/A

Ralf