• Hello, Guest! Welcome back, and be sure to check out this post for more info about the recent service interruption and migration.

Apple /// questions

ried

Well-known member
Picked up an Apple /// this afternoon, which came with:
  • 128K base unit
  • Apple Monitor /// (green)
  • ProFile 5MB
No software came with the machine, so I haven't been able to try running it properly yet. I know almost nothing about the Apple ///, but wanted to pick one up and learn. I've watched a couple of YouTube videos and am getting up to speed, but would love to read any insight that people may have about this unit. The hardware seems much older than my oldest machine (Apple IIe with Stealth IIGS upgrade), and I'm a little out of my depth.

The chassis plate that the logic board is attached to has some significant corrosion, but the board and its components seem in reasonably good shape. What should I be doing to take care of this old machine? Clean the board, re-seat chips, Deoxit? Should I fill the memory board with 5v memory chips? Anyone know where I can get one of the computer's missing feet? All advice welcome and appreciated.

IMG_6138.jpeg
IMG_6142.jpeg
 

ried

Well-known member
Any idea what's going on here? Is it a display issue? A computer issue? Or both?

 

pball52998

Well-known member
Glad to see another /// thread at the same time ;) saw your post on my thread!

I'd definitely reseat all the chips. Hopefully all yours aren't rusted out like mine. Those chips were known to "wander out of place"

For the bottom board (metal casing that it's screwed to) you can see my post, I used very fine sandpaper and go to town on it. I think I documented it? Lots of elbow grease!

After fine sandpaper I use barkeeper's friend on mine to clean it up.

Definitely turn down the monitor brightness and post what it looks like. Looks like a bunch of @ symbols in the middle?

Look forward to seeing progress with yours!
 

ried

Well-known member
I turned down the brightness on the Monitor /// and also hooked up the AppleColor 100. Same result on each. Next stop, reseating all of the board chips.

IMG_6225.jpeg
IMG_6230.jpeg

A quick video of the power on condition:

 

ried

Well-known member
Update: About 5 minutes after the ProFile 5MB was powered on and its "ready" status light showed a steady glow, it blew a RIFA cap in its internal power supply. Pretty good puff of smoke that smelled like burnt newspaper. Powered down, unplugged everything. Hopefully it didn't take much else with it.

IMG_6231.jpeg
IMG_6233.jpeg

This is 5MB, and the world's first 5.25" hard disk, according to Wikipedia. I'd guess it weighs at least 5 lbs. so... 1 lb. per megabyte?

IMG_6234.jpeg
 
Last edited:

stepleton

Well-known member
It's highly unlikely that the RIFA burst would have resulted in damage elsewhere. Replace the cap and you will probably be good to go.

The steady "READY" light is good news: your ProFile has passed its internal checks and is ready to serve blocks to the computer. There are plenty of tools for the Lisa that can show the spare count and other health indicators for your drive, but I don't know what's available for the ///. I'd love to get a /// someday to see about writing such tools.

Note that the board attached to the bottom of the hard drive isn't the same as what you find on a normal ST-506 --- it's an Apple original, echoing how the Disk ][ uses its own circuit board on a third-party mechanism, too. I mention this in case you ever choose to replace the hard drive in your ProFile.
 

ried

Well-known member
Thank you, @stepleton. I ordered replacement caps from Mouser and should have all of the chips re-seated by the time they're here. Fingers crossed we get a working system at that point 🤞

The Apple /// is overall a very strange, old machine. It feels every bit as sturdy and industrial as you'd expect with that one-piece metal chassis. Gives off a Cold War vibe, almost like you'd expect Soviet tanks to be built.
 

Paralel

Well-known member
If this is the one with the external mechanical interrupter, be very careful not to get anywhere near it when its moving. Just a slight touch will be the end of it.

st506.jpg

Being a stupid teenager, I did the exact opposite of what it said, which couldn't have been any clearer. I thought "how can one little touch cause so much trouble?" One little touch later, the drive never worked again, despite significant effort from a very talented IT professional. I really regret killing what was essentially a piece of computer history.

Also, if you need the service manual for the drive (not taking the Apple modifications into account) here is the original:


I find it to be quite a fascinating read, it really tells you just about anything you'd want to know about the drive. Using the service manual, given the diagrams, one could probably build an ST-506.
 
Last edited:

superjer2000

Well-known member
I find it to be quite a fascinating read, it really tells you just about anything you'd want to know about the drive. Using the service manual, given the diagrams, one could probably build an ST-506.

Thanks for the manual link! I love older hard disks and am looking forward to reading this.
 

ried

Well-known member
I was pulling several of the more corroded ICs from the logic board and ended up breaking a pin off of one of them (labeled LS133). I tried soldering a repair, but my skills are just not up to that intricate level of work.

IMG_6286.jpeg

Thankfully, these are still available on eBay. Ordered a replacement.

 

ried

Well-known member
Recap of the ProFile 5MB drive was successful! Replaced all 3 of the RIFA caps in its internal PSU and we're back to working with a steady red LED.

Next stop: Logic board.
 

ried

Well-known member
I'm at a loss. I have reseated all of the chips on the board, and replaced the one that I broke a pin off of. When powering on I see the exact same behavior as seen at the beginning of this process. What could be happening here? This appears immediately after flipping the power switch on.


What's my next step to troubleshoot this thing?
 

pball52998

Well-known member
Are you able to swap around some of the RAM chips to see if it makes any difference?

Specifically the ones in the top left of the RAM board are zero page ram. Take some from the left and move it to the right of the board and vise versa.

Any difference there?

The video I'm pretty sure like the ii is separate of the CPU/IO.

Do you have an oscilloscope to be able to dig into if you're seeing a reset signal and proper clocking from the 6502?

Something that I've been following almost to a tee is there reference manual:

See page 290 for a flow chart on no boot/problems in general.

Do you see a light on the keyboard? If not, you'll never pass initial diags either
 

ried

Well-known member
Thank you, @pball52998 for the advice and link to the service manual. Yep, the keyboard light works. I do not have an oscilloscope, unfortunately.

I'm going to swap the RAM chips around and report back. Great idea, thank you.
 

pball52998

Well-known member
Yep, the keyboard light works. I do not have an oscilloscope, unfortunately
Well that's a plus on the keyboard light at least!

I bought this guy for my project: https://m.aliexpress.us/item/325680...ctjVh2i&gatewayAdapt=glo2usa&_randl_shipto=US

Sorry if it's a mobile link but it's the ZEEWEII DSO1511G

Review from Adrians digital basement:

It's worked quite well for me.. and can plug into a TV! It was like $50 on black Friday. Just took a while to get here.

Others can chime in, buy you might need a scope like I needed to dive a bit deeper here

Look forward to hearing anything about the ram test! :)
 

ried

Well-known member
@pball52998 removed all of the RAM chips, cleaned the RAM board with Deoxit and then alcohol, dried and replaced the RAM chips while changing the position of each. No change to the power on condition. The investigation continues...
 

ried

Well-known member
Replaced all of the RAM chips on the board with new chips. No change to the power on condition.

I did read on another forum that the power supply might prevent the machine from booting if it's out of spec, so ordered a modern replacement from ReactiveMicro. I'm hoping that fixes it, because I do not have an oscilloscope and do not know how to use one properly. Testing individual chips on the board sounds like... fun.

The Apple /// is a challenging beast.
 
Top