Apple ][+ will not boot from known good card and drive

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Last seen: 2 months 1 week ago
Joined: Sep 19 2019 - 11:44
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Apple ][+ will not boot from known good card and drive

Hi all,

I have a good, working Apple ][+ that I have used to verify a disk ][ drive and controller.    I got an a new-to-me ][+ from my dad's attic.  It will boot to ] prompt with no cards inside.  When I instal the controller into slot 6, and single disk ][ drive, it attempts to boot on power-up, and does the seek to track 0 clackity-clack, but never boots a known good diskette.

Any ideas what on the main logic board I can look to repair/replace?




NovellNetware's picture
Last seen: 17 hours 57 min ago
Joined: Jun 3 2019 - 21:23
Posts: 70
I had issues with an applle 2 I purchased.

When I got my apple II plus a while back. The drive was qustionable on booting. Including the old disks. After cleanling and lubing the drive via instructions online. It booted all the time and most disks. At least is the drive light showing up on the disk drive? it sounds like it is and trying to boot. Also I don't know if you tried it in another apple or not. It the drive, card and disk work fine in another apple. I cannot remember what place. But I beleive in one of the manuals I was reading while fixing my apple ii plus. One or two chips can go bad and thus non of the cards will work in the slots. That is just a guess.  Pluas I can assume you can press ctrl - reset to get out of the boot and drop into applesoft basic?





Last seen: 2 months 1 week ago
Joined: Sep 19 2019 - 11:44
Posts: 24
Card and drive both work in a different Apple ][+

I have confirmed that the disk controller card works in a different computer.

I have confirmed that the disk ][ drive works with that same disk controller on that same other computer.

I have confirmed that a diskette works (Adventure) in that disk drive on a different computer.

The problem appears to be within the Apple ][+ itself, independent of the disk controller, the disk ][ drive, and diskette, which all work on a different computer just fine.

What might be the problem within the Apple ][+?   Is it a chip, a set of chips, that impact IO to the good disk controller?   Is it one or more capacitors, or diodes?   It seems all the online research is focused on the drives or controllers, which in my case I know are both working fine.  So it's inside the computer itself.

I need the help of the fine membership of Applefritter!

macnoyd's picture
Last seen: 4 hours 11 min ago
Joined: Oct 15 2012 - 08:59
Posts: 608
My first thought ...

For starters, check the F8 ROM ... Is the F8 ROM the Autoboot ROM?  Same in both computers?

Is there a Language card in your Apple ][ that has an F8 ROM on it?  It it the same F8 ROM version?

Last seen: 21 hours 48 min ago
Joined: Jun 18 2010 - 13:54
Posts: 280
Since it attempts to boot, it

Since it attempts to boot, it's not a ROM issue. Possibly an expansion slot / bus issue; try moving the controller to a different slot. Or it might be a weak power supply; measure voltages with and without the drive spinning.

Last seen: 2 months 1 week ago
Joined: Sep 19 2019 - 11:44
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Swapped H2 and H14 with known good; still not working

Hi.  I tried swapping ROM F8 anyway; as expected, no change.  When I power on the computer it still moves the head to track zero and then just spins.

So I have a very old magazine troubleshooting guide - Apple ][+ Home Repair Guide by Richard L. Edmonds from A+ Magazine June 1984

I swapped 74LS138 in position H2 with one from working computer.  It did not change the situation.

Then I swapped 74LS251 in position H14 also with one from a working computer.  No difference.

I have a second computer that is behaving exactly the same way.   Luckily, I also have a third machine that is fully working that I can use as a source for chips, and also to continue to confirm that the drive controller and drive itself continue to work.

I have also checked the voltages of the power supply and they are good, both idle and with the drive spinning.


I am running out of ideas.  Does the additional information give anyone ideas of what I should try next?  



amauget's picture
Last seen: 3 days 23 hours ago
Joined: Jan 3 2011 - 11:34
Posts: 287
New things you can try



Like Jeff suggested, have you tried to move the controller to a different slot ?

You can also try to swap F12,F13 & H12.

Last seen: 2 months 1 week ago
Joined: Sep 19 2019 - 11:44
Posts: 24
One step backwards...

I swapped F12, F13 and didn't work.

Then swapped H14, still no go.

Put original chips back and now... the working-source computer will not boot! Aaahh!  bummer!

I guess I'm going to order some 74LS138's and try to get the source computer working again.   Then, I think it's time I learn how to use other diag techniques... because maybe something on the target bad computer just ruined those working source 74LS138?   Seems now my boot problem is over on the formerly working machine...   Have I wrecked a set of chips over there too?

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