I have two Disk ][ drives, three disk controller cards, and around thirty bootable disks (I have run them successfully before). But whatever combination of drive, controller, and disk I try, my Apple //e will not boot. What could I do to rectify the problem?
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Due to the fact that they all together have been working before,
this sounds to me to be rather more a problem of the board or the slot.
Do you have chance to check out the devices at other mainboard or computer ?
If they work there then it´s not a problem located in the devices
but instead a problem in the computer...
It would be usefull to add more info´s:
Does the computer complete bootup to prompt without controller and drives connected ?
Do the drives spin/recalibrate or not while bootup ? (i.e. are the +12 Volt present from the power supply or
is the powersupply failing to supply with +12 Volt - or is that Voltage to low ) ?
Does the LED in the drive turn on while bootup ? ( i.e. is the drive selected or
is the drive not selected ? )
Do the disks boot at other computer ? Or did the current setup erase/destroy that disks?
Are any of the driveinterface cards work in another computer ? Or did the current setup
destroy something in the interfacecards ?
Depending to such answers the location of the trouble can be located at the powersupply, the mainboard,
or the drives themselves... so it´s realy important to give more and more precise information....
I would add, are you familiar with the procedures for handling the boards and computer innards in an antistatic way? If not, it is easy to damage the DD][ cards and the motherboard of the Apple IIe with a static jolt from your body.
When I turn on my Apple with a disk controller in slot 6 and no disk in the drive, the drive chugs just like it should. But when I insert a disk and restart, the drive just ignores it. I've tried about twenty disks with the same result. This happens if I remove all my other cards, if I switch between controllers, if I switch between drives, and if I switch between slots.
EDIT: I unfortunately do not have another Apple to test with. But I do know that if I remove the disk controller, I get "Apple ][" and an Applesoft prompt on the next line, just like I should. The cassette ports, video out, keyboard &c. work perfectly, whether there is a disk controller or not.
Also, I tested my drives' seeking capabilities outside the computer, and they seek back and forth perfectly.
Is there any chance that the drives were plugged into the controller incorrectly at any point and turned on for any length of time?
Supposing that I did --- what would be the effects, when I corrected my mistake and attempted to run a disk?
If the cables have been connected wrong side around there is a big chance
to kill the electronic circuits at the analog board of the disk drive and
later when connectig damaged drive with cables correct installed to the interface
the damaged circuits on the analog board start killing the interface card and
then in next step next drive connected to the next controller the game repeats again .....
tommorow i will take time for extended reply....
I have decided to make a complete page related to the mistakes mentioned here in the threads
and making pictures and advice list on dignostics and repair......
the result will be a kind of repair guide to most common damages of DISK II drives, list up
in the ranking how often they happen, what causes the damage - and how to solve the repair....
this requires a bit more "homework" .... i guess the page will be finished tommorow evening
including pictures and explanations and closeup´s from the circuitplans...
and listing of some current sources for IC´s and approximate amount requested to spend for that parts....
therefor please take a bit more time waiting - it´s worth waiting one or two days more till Friday or Saturday evening.
I will place here direct link to that repair page when finished as soon as possible.
One of the most prevalent problems that can occur is the 74LS125 chip on the Disk II analog card (the circuit board inside the Disk II) gets fried. If this happens, any disks you put in it can all get their boot track erased.
The 74LS125 is a cheap and easy to find part. See if you can source one (or 2) at a local electronics store and replace it in one of your drives, then see if you can INIT a disk successfully with that drive.
Like explained in previous posting this page is not complete yet
- but it allready contains information related to this thread:
page will be completed during next few days - so its recommended revisiting
i will publish statement after page has been completed....
I replaced the LS125s as BillO suggested, and my disk drives now work fine! But now begins the project of restoring the disks that were damaged by the defective drives...
Thanks all for your help!
Yes, track 0 will be toast on any disk you inserted while the drive was energized.
@BillO, any idea why this particular IC is prone to getting damaged? Was it a run of slightly flakey chips, or is a just a matter of this is the component with the shortest lifespan in the circuit?
I'm no BillO, but I'll chime in anyway.
They are damaged when you don't align the ribbon cable to the header on the Disk II card correctly. If you're off by one row (not sure if it's vertical or horizontal that matters, or fore/aft) and turn the machine on, you get +12v applied to the wrong place and *poof* out comes the magic smoke.
Like David said.