Help me Fix my Apple II Plus

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Help me Fix my Apple II Plus

Hello all,

 

I have just recently inherited an Apple II+ Plus from my late godfather. I got it working with little trouble, but then the power supply blew up. I bought a replacement for it from ReativeMicro and just installed it. Since installation I seem to be having trouble with getting the Apple II to read disks. Now when turning on the Apple II, it boots and then just stays at the Apple II screen with the drive spinning, I can get it to boot to BASIC by pressing CTRL+RESET. I've tried a new Disk interface board but it didn't change anything.

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rtff

This is a common problem with many threads on Applefritter discussing the causes and solutions.

For example, see this thread and this thread. Better to be safe than sorry and do the tests in this thread, too.

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Thank you for pointing me to

Thank you for pointing me to those threads. Unfortunatly I've gone through the basic troubleshooting steps such as checking the interface card and the disk drive. I've actually tried different drives and boards and cannot seem to get this pinpointed.

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macdude2010 wrote:Thank you
macdude2010 wrote:

Thank you for pointing me to those threads. Unfortunatly I've gone through the basic troubleshooting steps such as checking the interface card and the disk drive. I've actually tried different drives and boards and cannot seem to get this pinpointed.

I'm curious what are the disks? Are you writing to fresh "new old stock" disks with the very same drives, like via ADTPro, and then reading them? Or, are you trying to read old disks that have been lying about that haven't been read in years? I've found that ~40 year old disks haven't aged well but maybe that's just my small sample size.

 

But I think what you are describing is the common behavior, "plugged it in backwards and blew the 74LS125's", very common, https://www.applefritter.com/content/incorrect-disk-ii-connection-how-bad and it could very well have been somebody before you even if you are certain that your cable orientation was perfect.

 

When you say you've gone through the basic troubleshooting steps, it sounds like you're just looking at the appearance of the chip? You would have to build a circuit or use a logic analyzer or some such to check whether 74LS125 is functioning, not a basic troubleshooting step, the IC costs less than $1 so I would just recommend to go ahead and just replace them, and be very certain about cable orientation when plugging them in next time.

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Inline with what others have

In line with what others have said,  how careful were you whenever you did anything with the controller card and iterface cable? Because the connector is unshrouded, it's not uncommon for people (even those who are exremely careful) to put the cable onto the header incorrectly. So basically shifting the connector to either side by jsut one pin. The result of that is either 12V or -12V (depending on the shift) is placed on the 5V line used by thte drive.  Both are bad and why you've seen the comment about the 74125 chip or similar damage the 125s are a frist-in-line part and this type of damage is quite common even with devices other than disk drives.  

 

But, that's just one of several possible problems and fixering a damaged IC requires some better diagnosing or replacing parts. It's much easier if you have expereinece with diagnosing and rework. Is that you? If not, where are you located? Maybe someone nearby could help you out...

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I presume that you only have

I presume that you only have one disk drive then?

If not, have you tried with another disk drive in the D1 position?

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By troubleshooting, I did

By troubleshooting, I did replace the 74LS chip on my original board as a test, but it did nothing. I also tried 2 other disk drives (bought another one from eBay and I have a second one) as well as completely replacing the interface card. None of this has allowed me to read the disks I have on hand.

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I think someone already

I think someone already mentioned the only real way to know if it's a drive thing or media thing would be to format a disk and write a file to the disk. If your speed is off you won't read anything written by a drive at the right speed. With formatting, wrting and reading you take the speed out of the equation for a moment (I still needs to be right, but less cricital for this test)  If the drive can format a disk, write and read then you know there's a drive/media issue. These drives are pretty solid so you're doing the right things but that you're having multiple failues (different disk II controller cards, different drives, etc) the proability of the drives being the problem starts to deminish. 

 

 

Disk speed is important and you can check this with with nothing more than a LED light bulb with its AC flicker. With the case off and the drive upside down you can monitor the speed calibration markings. With an LED bulb at either 50Hz or 60Hz the speed markings should appear static when running. You can boot the system without a disk inserted and let the drive run for a minute to check the speed. If speed checks then try the format, write, read test. 

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Sounds to me like the

Sounds to me like the hardware is OK.  If the drive is just running and says "Apple ][" at the top, sounds like you need a bootable disk installed (some kind of DOS).  

 

Ah, disregard-- looks like you have tried alternate media, etc.  Hope you get it resolved, my first Apple was a ][+

 

Enjoy

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