Apple IIe with weird screens at boot.

[flaviosr]

Dear Group,
I was using my Apple IIe when something exploded in the external FDD Duo.
After this, the Apple IIe has two behaviours: when the FDD card is inserted, "Apple II" appears on the screen without any other possibility (since the FDD is dead), and I think this is normal.
If I remove the FDD card I get garbled screens, more or less always like the attached pictures.
Any idea on what it is happened?
Thank you

 

[oldpcguy]

First remove all cards. Once done power up the system. Do you hear a beep? If so what happens when you press CTL-RESET? Do you see the Applesoft BASIC prompt?

 

[flaviosr]

I think I found at least one the causes.
Please note that I already removed all cards when I made the photos.
Today I started the computer and everything was OK.
I started wondering about the card of the attached photo... I tried some on / off and the Apple worked fine. I mounted only the card and I got garbled screen. I turned off the computer, removed the card, turned on the computer and... garbled screen.
CTRL and RESET and the computer booted fine. I reinstalled the card and I got the garbled screen without any beep. CTRL and RESET and the computer booted fine with the SW of the card.
We could think about an issue on the card but I do not understand why when I mount and unmount the card, the computer remember about "her", at least for a while.
Could the issue be related with a capacitor related to the boot process? The PSU? I am not a technician so I hope I did not write a crazy thing...

 

[oldpcguy]

To clarify when you power up the system (with or without the card in post #3) it may or may not display a garbled screen? However each time you use the RESET key the system behaves as expected?

 

[flaviosr]

My experience up to today is:
° if the card has not been inserted for some boots, the computer start correctly;
° if the card is inserted, the computer shows garbled screen but, if reset is pressed, the card works in the expected way;
° after the card is removed, the computer still shows garbled screen but, if reset is pressed, it boots correctly;
° sometimes, after the card is removed it boots in the right wait immediately; in one case I had to wait for the day after.

 

[mbliss11]

It almost sounds like the system is not resetting all of the time on power up but a manual reset works.

The iie has a built in diagnostic. Hold down both the apple keys and hit reset when you get it to boot correctly. Do you get any errors?

If no errors I would think that there could be something up with the reset line. I think the card may be a red herring. If the cpu is not coming out of reset on power up you would get junk on the screen like that I would imagine

 

[mbliss11]

If you have not done so try reseating the cpu and the IOU chips after diagnostic test results and see what happens on power up after that.

 

[flaviosr]

A small step. The diagnostic reports "Kernel OK".
If I start the computer with the card I have the "garbled screes", then I reset the computer and evrything is ok. If now I turn off and on the computer (3 seconds, no more) the computer starts in the right way!!!
This is stable.

What IOU chips are?

Are there any capacitor involved with the reset process?

 

[mbliss11]

A small step. The diagnostic reports "Kernel OK".
If I start the computer with the card I have the "garbled screes", then I reset the computer and evrything is ok. If now I turn off and on the computer (3 seconds, no more) the computer starts in the right way!!!
This is stable.

What IOU chips are?

Are there any capacitor involved with the reset process?

If you do not have the card plugged in and boot the computer on a cold boot (has sat for a while maybe a minute without powering on) what is the behavior? Garbled screen? Or does it boot correctly?

The CPU is a 6502 and the IOU chip is a custom chip 344-0022-A. They should both be in a socket. Try to carefully take them out when the computer is turned off and put them back into their socket. If you have contact cleaner spray it in those sockets and then put the chips back in.

From my understanding the computer’s reset signal can come from the keyboard, the IOU chip and the card slots. Since something went bang with your disk controller card I would suspect that to be the culprit for not booting correctly. However I would not suspect that you would be getting this behavior with the card out of the machine. Since you can do the reset with your keyboard the power on reset signal in the IOU chip may not be working correctly.

 

[oldpcguy]

If you do not have the card plugged in and boot the computer on a cold boot (has sat for a while maybe a minute without powering on) what is the behavior? Garbled screen? Or does it boot correctly?

The CPU is a 6502 and the IOU chip is a custom chip 344-0022-A. They should both be in a socket. Try to carefully take them out when the computer is turned off and put them back into their socket. If you have contact cleaner spray it in those sockets and then put the chips back in.

From my understanding the computer’s reset signal can come from the keyboard, the IOU chip and the card slots. Since something went bang with your disk controller card I would suspect that to be the culprit for not booting correctly. However I would not suspect that you would be getting this behavior with the card out of the machine. Since you can do the reset with your keyboard the power on reset signal in the IOU chip may not be working correctly.

Not all IOU chips are socketed, I have a IIe board where the IOU is soldered. The IOU appears to generate the power on reset signal (my Apple IIe Reference Manual is fuzzy so it's difficult to read). The best way to troubleshoot the reset is to use a scope. Do you have access to one?

 

[flaviosr]

I tried with no results.
So I decided to use my mental superpower to convince the Apple IIe to work... with, again, no results.
I suppose that, at a certain time, the Apple IIe used its mental superpower to remember me that not all slots are the same and the order of the cards is important (or at least I remember so) ... so I tried different combinations and I had different results with the various cards. Now the Apple IIe works as expected but I have to still mount all cards. I would like to mount a 80 column card (and I can only use its specific slot), the FDD card, the above card, a mouse card and a serial card. This last seems tough and I could decide not to install this last if too problematic.