OT: Integral PC Floppy Drive



#12

I have finally gotten home from an extended business trip, and found the Integral PC I bought on eBay three weeks ago waiting for me. I'm having a blast putting together a system from the disk images at http://www.coho.org/~pete/IPC/ and http://hpmuseum.net/exhibit.php?swc=9 . Although I lack an HP-IB hard drive (which I haven't missed, up to now, with my 80 series and 9816 machines,) I do have two 9122/Ds that give me about 2.4 MB of storage to play with. I would have close to 3MB, but unfortunately, the internal floppy drive appears hosed. Either that, or I'm not operating it correctly. It appears to me that the "up" side of the floppy (with reference to modern PC floppy drives) faces toward the screen. I cannot insert the floppy either way, but if I press the release button at the top-right, I can see the shuttle moving from right to left. When it lines up with the opening, I can insert the disk. The drive access light comes on, and the drive spins away for a bit, but then stops, and HP-UX shows an error to the effect that /dev/A could not be accessed. Things don't work nearly as well if I put the disk in the other way. 8) It sounds to me like a mechanical problem that might yield to some adjustment. I can read up on floppy drive maintanence in my copy of "Upgrading and Repairing PCs" but I thought I'd ask here regarding this specific drive. Does anyone have advice or documentation for the IPC? I'm using modern quad density disks with tape over the hole opposite the write-protect tab.

Thanks,

Howard


#13

It's a long shot, but you might want to try getting some real double-density floppies. From what I remember from my Macintosh II days, using high-density media in double-density drives was supposedly unreliable -- at least that's what everybody said; I must admit I never tried it myself (and what you're reporting sounds a lot worse than merely "unreliable")...

- Thomas


#14

I don't have any real DS/DD disks, unfortunately. I do think it's a serious mechanical problem.

I'm in good shape because of the external drives. But I may have a whack at the internal drive, merely as an excuse to open up the machine. 8)

Regards,
Howard


#15

I have an Integral (wonderful machine), I have, as ever, taken it to bits...

There are schematics on the Australian site, but I know there to be errors in them (particularly around the address decoder on the Logic A board). An updated version (including the diagrams for the internal modem) is on the latest version of HPCC CD-ROM.

OK, back to the problem. I can't remember which way the disk goes in an Integral, but the drive mechanism is the same as the one in your 9122 (or 9133, or...), without the front panel and eject button. So the eject button on the front of the Integral should give you the orientation of the drive.

You do have to use DD disks. HD ones will go in, but won't activate the disk inserted sensor (and they're the wrong coercivity). So that's not the problem -- yet -- but it will be a problem later.

Now, there's a well-known problem with these drives. The grease on the eject mechanism goes hard and sticky with age, the levers don't latch up properly. If you're unlucky, the upper head will catch in the slot in the disk when you eject it, and will be ripped from the gimbal spring. At which point you need a new head carriage. Finding one is difficult, fitting it (which involves doing the head alignment) is marginally easier.

But whether that's happened or not, you need to remove the drive to investigate. The Integral is not hard to work on, but you need a set of Torx drivers. Start by removing any expansion cards, then undo the 2 Torx screws on the back. Remove the back cover. Under it is a sheild plate held down by 6 Torx screws. Take that out next and you're looking at the component side of the Logic A board (CPU, memory mapper, ROMs, RAM, HP-HIL).

Disconnect the 2 cables from the back of the floppy drive, then undo the 2 screws in the bottom of the cable well next to the built-in printer, and the single screw on the bottom of the floppy bracket. Slide the bracket and drive out rearwards, remove the eject button and spring before they get lost.

If you want to go further on the main machine, undo the screws holding the vertical chassis plate in place (this has the Logic A board on it). Ease it up, reach under it and unplug the cable from the back of the display. Unplug the cables from the bottom edge of the 2 boards (HP-HIL, Power (one on each board), HPIB, etc), Move the chassis plate so you can unscrew the shield from the logic B board. Unplug the cables going to the Thinkjet mechanism (carriage flexiprint, the 2 motors, home sensor, paper sensor, control panel) and remove the chassis entirely. The logic B board contains I/O circuitry -- the HPIL link to the Thinkjet, the Thinkjet controller, sound, real time clock, disk controller, video controller, HPIB, etc.

The metal box at the bottom contains the PSU and expansion backplane. To get that out (with the chassis out of the way), undo the grounding nut visible through a hole in the expansion backplane. Then remove the 4 Torx screws on the side flanges and slide the whole lot out. To get inside, remove the nuts and torx screws holding it together and ease up the cover. I find it best to unbolt the HPIB connector from the back of this module at this point.

Back to the drive. Undo the 4 screws holding it to the bracket. Take off the cover by removing the single screw at the back. You can now see how the disk holder works. Examine the upper head. If it looks undamaged, or you want to go further, then you can dismantle the drive in the following order :

Remove the 3 screws on the bottom, lift off the foil shield, ease up the PCB and unplug all the cables going to it.

Remove the eject damper (rear left, 1 screw)

Remove the head load solenoid (2 screws, one holds an earth tag. Feed the wires through the chassis). Put clean paper between the heads to prevent them from touching.

The disk holder is held down by 4 screws from underneath.

To remove the spindle motor, remove the E-circlips on the sensor arm posts, lift off the arms and the compression springs. The motor itself is held in by 2 screws.

The head carriage can be removed by undoing the screw on the cover plate under the chassis and freeing the cable there. Undo the screws holding the clamps for the carriage rails, slide out the rails and the carriage. You should be able to refit the same carriage without affecting the alignment, if you fit a replacement, you need to check the radial alignment.

The disk holder comes apart by removing the obvious screw and the E-circlips. Watch out for small, loose spacers on some of the rods.


#16

Thank you for that detailed description, Tony!

Regarding media, the quad density disks work fine in both my 9122s. (Also in my 9121s and 9114s) I'm willing to believe there may be a problem with particular drives, or particuar drive models, though. But the mechanical problem is the first order of business.

Thanks again!
Howard


#17

Odd that you have no problems with HD disks. In the older full-height drives (used in the Integral, 9114A, etc), the disk-inserted sensor lines up with the HD-detect hole, so that the drive doesn't detect that a disk has been inserted if you use an HD type. I am told this was deliberate, the HD disks are the wrong coercivity and will not be reliable.

If you have any more questions on the Integral hardware, feel free to ask.


#18

I cover the HD detect hole with tape, so the drives accept the disks. As far as the coercivity goes, the HD disks can't be out of spec by a huge amount, since they actually do work. I'm sure they are less reliable than the proper media would be, but so far, they have been "good enough." It's probably a testament to conservative engineering in the HP drives. (Perhaps coupled with my not-so-stringent requirements.)

Regards,

Howard

#19

It was the media. Hats off to Thomas and Tony.

Thanks for offering to send me a couple to test, Dave, but I decided I needed more than a couple, so I bought 40 DS/DD disks off of eBay. I still have to perform the trick of pressing the eject button until I can insert the disk, but once that's done, I can format, read and write the DS/DD disks just fine in the internal drive. The wrong media still works in the external 9122s, so I figure I'll use them for "scratch" disks, and use the right media for stuff I want to last a while.

Thanks for all your help!

Regards,
Howard

Edited: 18 Mar 2006, 3:40 p.m.


#20

Howard Owen wrote:
> I still have to perform the trick of pressing the eject button
> until I can insert the disk, but once that's done,

This should NOT be necessary. If the diskette does not slip into the slot easily, the mechanism that lowers the printheads on the medium may need cleaning and lubrication.

This is NOT optional. You have to do it ASAP, before you destroy one of the heads. Follow Tony's suggestions to remove the floppy and lubricate the mechanism. Use your own judgement on how far you want to disassemble the floppy drive (I admit I was scared to go too far and simply removed the drive from the IPC and cleaned and lubed the parts that were accessible from the outside of the drive mechanism, i.e. I did not disassemble the floppy drive itself).

Do not use the floppy drive until you fix it.

Also take care to save the eject button as you remove the drive. It will prob. fall inside the case because it is not attached to the drive itself or the case. Before removing the floppy drive, you may want to add some sticky tape on the outside of the machine across the button to keep it attached to the case.

**vp

Edited: 18 Mar 2006, 7:52 p.m.


#21

Quote:
Howard Owen wrote:
> I still have to perform the trick of pressing the eject button
> until I can insert the disk, but once that's done,

This should NOT be necessary. If the diskette does not slip into the slot easily, the mechanism that lowers the printheads on the medium may need cleaning and lubrication.

This is NOT optional. You have to do it ASAP, before you destroy


I will second that. You _WILL_ damage the head if you catch it in the disk shutter because the disk holder doesn't latch up properly. I had to replace the head carriage in the floppy drive of a 9133H because of this. It was not fun. Doing the radial alignment is not easy without the special tool, even if you have the alignment disk and exerciser (I have those).

Quote:

one of the heads. Follow Tony's suggestions to remove the floppy and lubricate the mechanism. Use your own judgement on how far you want to disassemble the floppy drive (I admit I was scared to go too far and simply removed the drive from the IPC and cleaned and lubed the parts that were accessible from the outside of the drive mechanism, i.e. I did not disassemble the floppy drive itself).


Sometimes I forget that not everyone had a mis-spent childhood dismantling clocks, cameras, computers, etc AND getting them back together again :-)

More seriously, these drives are not hard to work on. Don't touch the screws holding the stepper motor or track 0 sensor PCB, or you will have to do a re-alignment. But everything else can come off and go back without problems. Yes, you do end up with a lot of little parts, but provided you keep them in order, it'll all go back. There are no springs to fly out, or anything like that.

I don't have a digital camera (and won't be buying one until they exceed the quality from my large-format film cameras...) so I can't do what would probably be very useful, namely producing a sequence of pictures showing what to remove in what order.

Quote:

Do not use the floppy drive until you fix it.

Also take care to save the eject button as you remove the drive. It will prob. fall inside the case because it is not attached to the drive itself or the case. Before removing the floppy drive, you may want to add some sticky tape on the outside of the machine across the button to keep it attached to the case.


I found it best to take out the 3 screws holding the drive bracket in place, then to put the machine screen-side down on my workbench. Lift the drive up (towards the actual back of the machine). Then reach inside and remove the eject button and spring. I don't like putting sticky tape on things, I am worried the adhesive will get somewhere it shouldn't

#22

Howard,

A quick check in my graveyard of old floppies reveals several DS/DD disks.

If you'd like a couple, let me know by e-mail.


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