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Darn. This II(+) doesn't look happy. Any suggestions?

N

nex

Experienced Member
Joined
Jan 17, 2011
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77
Location
Texas
The good news: I picked up a nice looking (ROM upgraded) Apple II.

The bad news: It doesn't boot.

I'm not sure where I should start, but I'm seeing the current screen (with or without cards) upon boot:

dsc0551xf.jpg


Upon physical inspection, everything appears to look ok for a system 30+ years old, but I'm at a loss as to where to start looking. I did test the power supply, and I saw normal voltages on all of the wires. If you notice that there's a chip missing (E-3?), I also have a language card that plugs into that spot. I've also uploaded a high-resolution image in the hopes that something might be more obvious to someone else, and I'd be happy to run through any recommended debugging steps.

To see the hi-res shot, click on the thumbnail:


Any thoughts?

I'd hate to just wrap this guy back up and put him in storage. Been waiting weeks for the system as well. :(
 
Few quick questions. Is it the same pattern/text every time? Does it do anything if you press a key on the keyboard? An easy thing to do is reseat any removable/socketed chips incase there is just a bad connection between the pins and motherboard.
 
I've found from servicing early Tandy machines and Apple machines that you get that sort of pattern when you have a ROM problem. However, take a RAM chip off the language card and put it in E-3 to eliminate a bad language card.
 
barythrin said:
Is it the same pattern/text every time?
Click to expand...

No, the text does change, but only after hitting Ctrl-Reset. Occasionally a Ctrl-Reset does not change the screen.

barythrin said:
Does it do anything if you press a key on the keyboard?
Click to expand...

No, pushing any other keys other than Ctrl-Reset doesn't appear to change the pattern/text.

barythrin said:
An easy thing to do is reseat any removable/socketed chips incase there is just a bad connection between the pins and motherboard.
Click to expand...

Not a bad idea at all. There may be some gunk that isn't obvious, so I'll methodically reset each removable chip.

I don't know if it's just a sign of age, but I noticed that the 6502 processor is absent of all markings. To be more accurate, what I assume is a 6502 is absent of all markings. I'm tempted to pop in a 6502 (might be a 65C02) from my working IIe as an easy test.
 
I noticed that the 6502 processor is absent of all markings. To be more accurate, what I assume is a 6502 is absent of all markings.
Click to expand...

After better lighting and stronger squinting, I can see that someone wrote "65C02" on the chip with a pencil/pen. :-D
 
Did you fill in the missing ram chip? Did you put it in the with the notch or dot the same with the rest of them in that bank?
 
Usually you get that kind of screen if you have something wrong with the first bank of RAM - that's the row of RAM closest to the keyboard. The machine will still boot if there are chips missing from the last bank - but not from the first. Try borrowing the entire last bank of RAM and swapping it into the first. If that works, then, one at a time, insert the chips you removed into the first socket in the first bank and try them - when you get to the bad one, you'll get garbage on the screen. You should only need to replace one or two chips - and you can steal them off the Language card until you track down some more.

-Ian
 
Just one small note as well as a humorous observation.

After removing the first bank (and before replacing the chips) the boot screen was essentially full of "?" characters.

There was a bug, literally, underneath one of the chips in the first bank. Reminded me of the origins of "debugging." :)
 
Eew. What kind of bug? I remember one time I got a nice score of computers for free and one of the keyboards was not responding so I took it apart and literally about 2 dozen silverfish came running out. :mad:
 
The missing chip was filled in. After that, I tried replacing the first bank of RAM with the last bank, but didn't have any success. I suppose it's possible that there are multiple chips with issues, so I may just try the first row with various combinations. Perhaps a mental cntrl-reset away from the system followed by a repeat attempt at checking the chips will help. ;-)

Apparently there were some modifications done to the machine. Can anyone explain why there was a ground wire connected to the 74LS138 chip in H-12? Also, any idea why there is wire going from 74S195/pin14{QA} (C-2) to 74LS174/pin-9{CP} (B-5) to 74LS174/pin-9{CP} (B-8 )?

Reference:
dsc0628c.jpg
 
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maybe a stupid question, but doesnt the II+ only use 6502 and not the 65c02 that you recieved? the //e and //c were made to use the 65c02? correct me if im wrong here.
 
Call-151 said:
maybe a stupid question, but doesnt the II+ only use 6502 and not the 65c02 that you recieved? the //e and //c were made to use the 65c02? correct me if im wrong here.
Click to expand...

Good question. I cannot find a reference/link, but I do remember reading that the 65C02 is backward compatible with the 6502. Can anyone confirm that?
 
nex said:
Apparently there were some modifications done to the machine. Can anyone explain why there was a ground wire connected to the 74LS138 chip in H-12? Also, any idea why there is wire going from 74S195/pin14{QA} (C-2) to 74LS174/pin-9{CP} (B-5) to 74LS174/pin-9{CP} (B-8 )?
Click to expand...

Any hypotheses about the above modification? Tonight I was planning to remove the mod and reseat the chips.

I've also ordered 3 banks of new 4116s (about $15) just to see if I have multiple bad chips.

Any other recommendations for troubleshooting? I know, the problem could be due to a number of things...and perhaps more than one single issue. Don't mind rabbit holes in the least bit -- the journey is almost always the most interesting part!
 
nex said:
I know, the problem could be due to a number of things...and perhaps more than one single issue.
Click to expand...

Well, having repaired a LOT of Apple II series computers over the last 35 years (starting with when they were new), there are about, oh, a dozen or so chips and combinations of chips that can cause this problem. I have a II+ coming from NC with a similar problem and using my chip tester, I'll have it up and running in a few hours. There are just too many variables and dead ends to fixing this stuff to make it more than an interesting hobby if you don't have the right equipment, a spare working unit and diagnostics.
 
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