Re: OT: Integral PC Floppy Drive Message #4 Posted by Tony Duell on 13 Mar 2006, 1:07 p.m., in response to message #3 by Howard Owen
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.
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