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On to the next project...a very lonely and ailing Apple ///

N

nex

Experienced Member
Joined
Jan 17, 2011
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77
Location
Texas
A few on here may remember that I spent some time rehabilitating a very sad Apple II. It took awhile, but now my II is running smoothly and is no longer producing any errors during testing.

Fast forward to this week and I was able to purchase my first Apple /// for essentially shipping (which wasn't really that cheap thanks to Steve's goal of selecting the heaviest metals known to mankind while designing the case). I knew the system would be in poor shape, but I want to say that this system's repair will benefit from the great feedback in this forum as well as quite a few lessons learned while repairing the Apple II. At this point, I haven't done much else other than physically inspect it and disassemble the components for easier access when testing. I'll most likely be following up with questions after I have exhausted the documentation available online, but if you're curious, here are some photos of the system in its current condition. Serial is 015114 for those that are curious, although it appears to have been upgraded to 256K (5V).





<- The Apple /// was known for running very hot...and we all know a picture is worth 1k words :-D

OK, now it's back to work!
 
Are those chips fused with some melted plastic? Guess they do run pretty hot!
Do you know what type of memory board this /// has? I did some minor repairs to an Apple /// a while back, several of the MOS 32kbit RAMs had failed. If you find the same thing happening here, you can replace one of those by piggybacking two 4116s and bringing out the chip select lines on the top chip.
Best of luck bringing this computer back to life!
 
I'm just waiting for some 74LS260 ICs to show up to, hopefully, conclude a 25 year on again, off again repair on a 12V Apple /// system with an external floppy drive in addition to the internal one.

I'm pretty sure that the 12V memory card was the one that used the 32K chips (which I have an abundance of) while the 5V system used 4164 chips and allowed for a greater total RAM configuration. From the picture, that looks like the newer 5V memory board.

Only problem is, the sucker's been dis-assembled for so long that I'm not sure where the hell the screws are LOL
 
gubbish: The chips were fused to those black rubber pads...which could also possibly be due to an extremely hot storage container. Only guessing about that, however.


The AIII motherboard that I have is the 820-0043-00/SK500-06 version, while the memory card that I have is the 5V 256K 820-0041-B version. Somewhere I remember reading that you had to be careful when mixing and matching motherboards with memory cards, but I do not recall exactly why this is important. Just to confirm, are these two AIII boards (mother+memory) compatible?

Oh, and the bad news is that I'm not getting any consistent video, however the red light at M4 does turn on. Occasionally a few bands will light up the screen, but I currently can't pinpoint the reason. I'll check whatever chips I can in the tester and see if anything is obvious.

Any recommendations for cleaning and protecting the metal board that is a bit rusty? I have a few metal brushes that can take care of the major oxidation, but some of those areas appear to require a bit more help.
 
Yes, the lightbulb on the keyboard is OK. Bold and bright...it was a beauty to see at first.
 
david__schmidt said:
No joke. Burned out bulb = machine won't start. It required a trip to your computer dealership to replace!
Click to expand...

Serious? Wow! I know that the AIII is a great anecdote for marketing and technical team collaboration failures, but wow.
 
nex said:
Serious? Wow! I know that the AIII is a great anecdote for marketing and technical team collaboration failures, but wow.
Click to expand...
Failure? I dunno. It's an engineered-in means of revenue generation. I know anecdotally of an early mainframe that required a service call if it was emergency-powered-off. It's not unheard of.
 
nex said:
gubbish: The chips were fused to those black rubber pads...which could also possibly be due to an extremely hot storage container. Only guessing about that, however.


The AIII motherboard that I have is the 820-0043-00/SK500-06 version, while the memory card that I have is the 5V 256K 820-0041-B version. Somewhere I remember reading that you had to be careful when mixing and matching motherboards with memory cards, but I do not recall exactly why this is important. Just to confirm, are these two AIII boards (mother+memory) compatible?

Oh, and the bad news is that I'm not getting any consistent video, however the red light at M4 does turn on. Occasionally a few bands will light up the screen, but I currently can't pinpoint the reason. I'll check whatever chips I can in the tester and see if anything is obvious.

Any recommendations for cleaning and protecting the metal board that is a bit rusty? I have a few metal brushes that can take care of the major oxidation, but some of those areas appear to require a bit more help.
Click to expand...

Go here http://apple3.org/Documents/Manuals/Sun Remarketing Do-it-yourself Guide for the Apple III.pdf page 29
 
Druid6900 said:
Go here http://apple3.org/Documents/Manuals/Sun Remarketing Do-it-yourself Guide for the Apple III.pdf page 29
Click to expand...

Ah..ha! Yes, that is exactly what I remember reading. Thank you! OK, so both the main logic and memory boards are 5V -- that's a relief.

Remember those two TTLs that were taking a ride on the rubber attached to the chassis? So, I plugged those chips (74S08 and 74S158 ) back in their sockets on the memory board, powered up the system, and after about 5 seconds I begin to feel a significant amount of heat radiating from the memory board. I quickly notice it is those same two chips and then power off the system. These chips were hot...ridiculously hot in fact. There is no doubt in my mind that the heat was enough for those chips to attach to that rubber...even after a few seconds perhaps. Although I didn't imagine that the same TTLs would pass a logic test, I went ahead and tried anyway. Both failed. So, I at least have one pair of chips that certainly need to be replaced. I'll test more of the chips (if my tester can read them) and then set out to find replacements.

One update:

Here is an image of the display output when the system is powered up (without the memory board):

photouj.jpg
 
Last edited:
Yeah, sounds like they are dead shorted. Hopefully, the current draw didn't cook anything else open. You should still be able to find 74S series chips around. I have the S08, but I'm not sure on the S158.

Good luck and keep us advised.
 
Here's some help with those IC's:

Here's some help with those IC's:

I actually just bought an IC for socket 74S08, and I looked 74S158 up, and I've included the respective links for each IC. You might consider ordering 1 or 2 extra, considering that these can be hard to find, and if there are current issues, you might end up with another set of dead chips. Anyways, here are the links: (mouser)

Socket #74S158 (QUADRUPLE 2-LINE TO 1-LINE DATA SELECTOR/MULTIPLEXOR):
http://www.mouser.com/ProductDetail/NTE/NTE74S158/?qs=sGAEpiMZZMutXGli8Ay4kBbWlp5gXOqndVJSp5hqXRA=

and Socket 74S08: (Quad 2-input Positive-AND Gates) (Identical Replacement):
http://www.mouser.com/ProductDetail...GAEpiMZZMtMa9lbYwD6ZGuuqVaqkGmOtjyt2q%2bOnco=

Hope this helps! :)

-Camden
 
Thanks Camden!

I was very close to purchasing all of the chips I needed to repair this little beast, but patience was on my side again. I recently found someone willing to part with both their Apple /// and Apple ///+ for a fair price. That said, both of the new systems look great...work fine, so I thought about just keeping this one for parts.


...but what fun is that? :-D

I can't wait to see the results either this weekend or the next. Photos will most certainly be provided.
 
Spoke too soon. One of the new systems works fine, although the other one failed the /// Diagnostics in the video section and has a few non-working keys. After opening it up for a closer look, I also noticed that capacitor C69 was completely missing. Good times. :-D
 
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