II+ won't load any disks

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Joined: Dec 19 2003
Posts: 10

I have some known good disks that will load fine on one of my II+'s, but won't load on the other with the exact same floppy drive and card. The drive just spins endlessly.

Since the disk subsystem isn't to blame, I'm wondering if this is some kind of RAM or power issue, or perhaps something else on the motherboard. I could go about replacing ICs one by one, but before I do that, I wanted to see if anyone knew of any immediate "things to check" for this particular issue - bad ICs known to cause this, etc.

I can at least get to a prompt, and normal Applesoft functions work fine.

Thanks for any help you can provide.

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speedyG's picture
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Joined: Nov 16 2011
Posts: 1286
Re: II+ won't load any disks

Hello Link,
under this circumstances there only remain 2 possible reasons:
1. The ROM F8 on the board contains the so called "Autostart-Loader" which is used to boot from the floppy....
so it might be possible that one of the pins of this ROM isn´t correct inside the socket or the ROM itself might be
damaged inside.... a change of that ROM would proof if this suspect turns out true...
2. of course it might also be a RAM-Issue but then i would expect the drive to at least try one or two steppings before
the failure shows up.... because you are not able to boot it might be usefull to switch to the monitor make a call to
the hires pages and fill them up with bytes by programming a short loop and while looping to have a second loop to
change the bytes by one bit ahead and then watch the screen while executing of the code... of course that´s not a
perfect RAM test, but it at least checks out a part of the RAM ..... you could also do this with applesoft by basic
and some pokes...
3. last but not least there could be a exotic trouble ahead: only one slot being damaged.... try booting from another
slot... is another chance to try...
4. and very last chance : if the 12 volt branch of the supply is weak, then probably the spinning-speed of the drive
might turn out to be too slow...
speedyG

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Joined: Dec 19 2003
Posts: 10
Re: II+ won't load any disks

Thanks for the tips - I'll try replacing the Autostart ROM tonight. I'm not much of a programmer but I'll see what I can figure out about #2.

One thing I forgot to mention: a few times when I was busy swapping around Disk II drives and cards, I'd flip the power switch and there would be a rapid tik-tik-tik-tik-tik from the power supply. It went away when I removed and reinstalled the card and cable. Do you know what this would be a symptom of?

speedyG's picture
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Joined: Nov 16 2011
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Re: II+ won't load any disks

the ticking is the electronic protection-switch that indicates a shortcut at the output....
you shot-down one of the IC´s on the board or card...
did you forget to switch off power when moving the card ?

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In early days I had a lot of money but no time - now I have no money but a lot of time....
the second part includes less friends but a lot more joy on life....

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Joined: Dec 19 2003
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Re: II+ won't load any disks

After some further testing, I think the power supply is the culprit.

I was going to try your steps tonight, and then decided I'd mess around a bit more before that. With one drive connected, I was able to boot off one of the known good disks. Of course, once I got a DOS loaded, I had all I needed to regenerate ADT, DOS 3.3, Copy II Plus, etc.

THEN, I powered off, connected a second drive to the Disk II card, and powered back on. The machine behaved exactly as it had initially, refusing to boot anything, including known good disks.

Removed the second drive, powered back on. The first drive booted fine.

Reconnected the second drive, powered back on. No boot.

Repeated this a few more times. Same results.

Tried in slot 5 instead of slot 6. Same results. I also noticed that, with both drives connected, the first drive was spinning down more quickly than it should have after CTRL-RESET. Like, spinning down for one second instead of two. (Roughly.)

Swapped in another Disk II card. (And yeah, I'm very careful about powering off before swapping out any cards.) Powered back on. The power supply went tik-tik-tik-tik-tik-tik. Quickly powered off.

So what I'm thinking at this point is something like your #4, unless it's possible that I have a bad ROM *and* a bad power supply.

I have a spare power supply sitting around; tomorrow I'll swap it in and see what happens. I guess at this point I should count myself lucky that I haven't fried anything (from what I can tell). When the machine does boot, it runs rock-solid.

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Joined: Feb 2 2012
Posts: 8
Re: II+ won't load any disks

1) First thing to do is clean the drive head.
With floppy disks being around 30 years old, if they weren't properly stored they will leave a brown residue on your disk drive head, and that's when it can't read or write your disks thru all that residue.
All you need is a q-tip with some rubbing alcohol to remove it.
2) Check and adjust your disk drive speed.

These 2 things are better than replacing a bunch of parts.

speedyG's picture
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Joined: Nov 16 2011
Posts: 1286
Re: II+ won't load any disks

Hello Link,
cleaning the Read/Writehead is of course a usefull task ...

but if the Computer boots fine with one Disk we can resume that F8 and RAM is fine and that the slot is OK.
The fact that the ticking noise of the powersuppliy starts, when the second Diskdrive gets connected spots out another point:
If you swap the Diskdrives ( only one connected ! ) and the boot works fine then it might be the powertransistor on the controller in the branch for the second driveconnector or a LS-chip related to the second driveconnector.

If the swap turns out ( the formerly second ) Drive to fail in front position as Drive one the drive itself is bad ( i guess this to turn out to be true ! ) and probably causes the powersupply to fail. This is usualy caused by the common mistake that the flatribbon-drivecable has been connected once wrong way around and the 74LS125 at the analog board of the drive to be fried...

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In early days I had a lot of money but no time - now I have no money but a lot of time....
the second part includes less friends but a lot more joy on life....

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Re: II+ won't load any disks

Well, you were right and I was wrong! I swapped in a third controller and a third drive - and they worked perfectly. I took the opportunity to load a diagnostics disk and perform RAM/ROM tests on the II+. They checked out fine. And I powered on and off several times successfully, so the power supply is fine too. So some combination of the other two drives and two controllers I was using is bad.

I need to do more testing tonight to narrow down exactly what piece(s) it is. For now, I'm just glad that the computer itself is okay.