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Broken Apple IIe - garbage screen

Neo-Rio

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Joined
Feb 13, 2016
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40
Hi, my first post.

I picked up this apple IIe (looks like a PAL version) in a garage sale, but it won't boot.
It won't beep. The drive won't respond. There is a light on the motherboard that goes on... but the video display is all blocky garbage.

I cleaned up the motherboard, and looked at some repair manuals that suggested investigating the CPU and one of the ROMS. I tested both and found them to be OK.
I actually borrowed a CPU from a Commodore 1541 disk drive (MOS 6502), no change.
Removed the EF ROM completely and no change there either. Tried to burn a replacement EEPROM of that chip and no change.

So now I am stumped. Can anyone help?
See attached pictures.
 

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retrogear

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Well the first step is reseating the socketed chips. No beep at power on involves 6502, ROM's (especially reset routine in F8 ), IOU, HAL.
Verify power supply voltages (probably ok) but then would need to substitute chips from a parts spare board. Otherwise an oscilloscope to
chase down the waveforms.

Larry G
 

Neo-Rio

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Feb 13, 2016
Messages
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Well the first step is reseating the socketed chips. No beep at power on involves 6502, ROM's (especially reset routine in F8 ), IOU, HAL.
Verify power supply voltages (probably ok) but then would need to substitute chips from a parts spare board. Otherwise an oscilloscope to
chase down the waveforms.

Larry G

Yeah, I tried reseating the socketed chips... to no avail there.

The CPU must work because I tested it in a Commodore 1541 drive (which also uses a 6502) and it worked. Swapped it with the original MOS from the drive, and it made no difference.

I might try wiping my eeprom and programming it for the other chips to see if that makes a difference with them.
Not sure about spare parts for the IOU and HAL though -- if they are the dead chips.

Will have to brush up on my multimeter-fu.
Does anyone know of a source for these spare parts?
 

retrogear

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Unless your desoldering and soldering skills are very good, I would advise buying another motherboard on ebay since the Apple IIe ones are still relatively cheap and try making one good out of two bad.
The odds of them having the exact same problem are slim. Yes, any chip like the ram which is on the address and data bus can bring things to a halt if they short a bit out. The only source
of proprietary Apple II chips are ones being pulled from boards anyway.

Larry G
 

Neo-Rio

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Funny you should mention that, because I did have another Apple IIe with exactly that same problem, which I then sold off. So I'm guessing this issue is fairly common - but not 100% sure what causes it.
I might have to try the shotgun approach... but I can at least start with the chips I can replace.

...and my desoldering skills are pretty good. Had lots of practice repairing Commodore 64s.
This is just my first Apple II repair :)
 

Neo-Rio

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Feb 13, 2016
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Good. Keep us informed. It's hard to see threads end without a solution reported.

Larry G

Well the good news is that I was able to fix the board,... and YES... it was the RAM
The thing was, it wasn't just one 4264 RAM IC, but FOUR dead ones.

What I did was to desolder and remove all the RAM, then resolder IC sockets in place (nearly pulled a trace on the motherboard doing this! :crazy:)
Then I put all the apple RAM back in the new sockets and swapped out one apple RAM with an old model Commodore 64 RAM (4264-15) and rebooted.

As I replaced each RAM, the pattern changed from blocky garbage screen junk to Apple II character set garbage screen junk
This slowly improved until I saw the screen junk glitch with characters ticking over, and then far enough that the Apple II beeped, booted properly, and gave me a command-line.
Then I did a self-test and got a KERNEL OK

Then I replaced each RAM chip back with an apple RAM chip and ran another self-test to test the RAM. From this I was able to determine which apple RAM ICs had become toast.
I was quite surprised that half the original apple RAM was effectively dead.

Also the Apple II seemed quite happy with the Commodore 1541 6502 CPU :)
So my Apple II is now part Commodore, but that's OK

Now for the next trick... to get the disk drives working.
The disk drive is plugged into socket 1 of the "Drive II interface card", but it does not power up and spin. The Apple II goes straight to the command line.
I recall back in the day that the Apple II would auto boot the first disk in the drive... :/
I must be missing something....
The disk interface is in slot 7 of the Apple IIe motherboard
 

KC9UDX

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Slot 7 will work fine. Boot order goes from 7 down. So, if you have a card in 6 and one in 7, the one in 7 will boot.

6 is standard for one drive, and there are a few times when it does matter, though.

It sounds like the Disk ][ interface card is kaput.

I hope that 6502 says "CSG" on it :)
 

Neo-Rio

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Feb 13, 2016
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I tried putting the interface card in 6, and tried putting the drive plug on the pins both ways (discovering that the wrong way causes the Apple to crash on boot!)
The drive doesn't spin or light up and the Apple doesn't even attempt to spin the drive. I'm just dropped off at a command prompt at boot.

Oh well, I at least can play cassette based games from the online Apple II gameserver.
Might have to look at the interface card or disk drive for issues.

The 6502 is a MOS. I'd have to go raiding a 1541-II most likely to get a CSG one I think ;)

Just two more questions:
That switch under the case - what does that do? It doesn't seem to control the power or anything.
And the keyboard light.... Does that only work if the CPU is a 6C502 or somehing?

Thanks for helping a newbie out!
 

KC9UDX

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Plugging in the drive the wrong way fries the drive, or was it the controller? Either way it's not good.

Switch under the case? The only time I've seen that is on Platinum models, and it changes the font for foreign language characters, I think.

The keyboard light is burnt out.
 

retrogear

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Yea the thing about the Disk II cable is the power for the drive is on that cable also, not like a PC where it's just data lines and separate power plug. Offsetting the pins by one fries the controller which is easy to do. I looked at the schematic of the Disk II controller and analog cards and it appears that reversing it would put +5V on the -12V line into the drive. Nothing else gets crossed up as far as I can tell. And the analog card in the drive only uses -12V to an offset adjustment control so I think the drive would be ok. You might only have a bad controller card. They are on Ebay quite often and are fairly cheap if you watch for one. Make sure your ribbon cable is centered on the pins and the ribbon moves away from the card.

You might need to check capacitor C5 on the drive analog card since it got reverse polarity but if you didn't have it on very long, I bet it's ok.

Larry G
 

Neo-Rio

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Thanks for your help.
Looks like I may need a new disk II interface controller card (or somehow fix the current one I have)
...and I found a tutorial on replacing the keyboard light, so I might give that a go.

Also, any recommendations for Apple II mass storage devices?

Many thanks.
 

HoJoPo

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Thanks for your help.
Looks like I may need a new disk II interface controller card (or somehow fix the current one I have)
...and I found a tutorial on replacing the keyboard light, so I might give that a go.

Also, any recommendations for Apple II mass storage devices?

Many thanks.

CFFA-3000 is the most versatile: http://dreher.net/?s=projects/CFforAppleII&c=projects/CFforAppleII/main.php

And, unless you have a bunch of Apple II floppies, since it emulates the Disk ][ you won't need to fix you controller card....

Since you have a IIe, you'll want the disk change remote as well.
 

Neo-Rio

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Feb 13, 2016
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CFFA-3000 is the most versatile: http://dreher.net/?s=projects/CFforAppleII&c=projects/CFforAppleII/main.php

And, unless you have a bunch of Apple II floppies, since it emulates the Disk ][ you won't need to fix you controller card....

Since you have a IIe, you'll want the disk change remote as well.

Thanks.... could be on my wish list when I get some money.

and on closer inspection of the controller card, it does look like the capacitor on it was already blown on the negative side when I got it!
Just need a replacement capacitor maybe.
What cap do I need? I can't seem to read what's on the capacitor itself.
 

retrogear

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Is that C2? Then it's 22uf 16V. It's part of an RC timer. Definitely would keep the controller from functioning.
 

Neo-Rio

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Is that C2? Then it's 22uf 16V. It's part of an RC timer. Definitely would keep the controller from functioning.

Yep.Forgot to mention that I was looking at the C2. Might race down the parts store and see if I can score a replacement.

Hopefully the two drives I have here are OK and not shorted from the card and my stuffing about with the cable on the wrong way.

UPDATE: Changed the C2 capacitor with a 22uf 16V electrolytic cap, but no change.
Apple ][ still boots up, but makes no attempt whatsoever to boot from disk and immediately drops me at the command line.
I guess the controller is broken somewhere else. I hope the PROMS on the interface are OK, I may be able to consider swapping ICs or some of the other components.
 
Last edited:

retrogear

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Have the card in slot 6.
When it drops to a ] prompt go into the * monitor with CALL -151. Then type C600L
Are the first 4 bytes A2 20 A0 00 ? If so, then type C600G
What happens?
 

Neo-Rio

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Feb 13, 2016
Messages
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Have the card in slot 6.
When it drops to a ] prompt go into the * monitor with CALL -151. Then type C600L
Are the first 4 bytes A2 20 A0 00 ? If so, then type C600G
What happens?

Went to monitor, and did C600L
first four bytes were A2 20 A0 20 ... so the fourth byte was different
I ran C600G anyway and the computer hung. No disk activity at all
 
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