Resurrecting an Apple ][+

[Gorgon]

I built my first computer around 1975 using an Intel 4004 Processor, 2K of RAM and some logic on a perfboard. I wish I'd kept that Perfboard as it turns out there's not too many working 4004 based systems left in the wild.
I had friends in High School that had computers, a couple with Apple's and one with a SWTPC.
I never could afford a computer while in College but managed to do a lot of programming and hardware hacking on Apple ][/+/e clones. After graduating I picked up an Apple ][+ Clone Motherboard at Computer Parts Galore in Toronto round about 1985/6. It was a project that has sat unfinished since then.

Back in the mid 90s I obtained an Apple ][+ from a friend as partial payment for moving his business from the Apple 2 to a PC. It was in good shape and came with a 10MB Sider ][. Somewhere along the way I misplaced the SASI cable so I removed the HDD Controller. I later found the SASI cable but the controller has since disappeared.

 

The system was last powered on 10 years or so ago and my kids were greatly amused by Choplifter, Lode Runner and other vintage games. It then went back on the shelf.

 

With retirement approaching I finally have the time to get this Apple ][+ Back up and running again. My long-term goal is to get back into Hardware Hacking and Assembly Language programming.

My approach is to first do a gentle clean and restoration on the Apple ][+ then, with the help of an eBay find of a recreated HDD Controller Card, get the Sider working to pull the data off it and my Collection of 70 or so 140kB Floppies and, finally, finish the ][+ Clone board and retire the original motherboard to help preserve it.

[Gorgon]

Part 0: Research

 

Adrian's Digital Basement has a playlist on Apple 2 repairs and enhancements. Highly recommended.

 

I've been playing with AppleWin which is an excellent Apple 8-bit emulator that can emulate all the 8-bit Apple Computers (Apple I/II/II+/IIe/IIc/IIgs )

 

I used the Eastern Software House Apple II Macro Assembler (MAE) back in the day. I found a copy of the Disk Image over on Asimov but no manual. So I scanned the manual and uploaded it to the Internet Archive and the Disk Image as well.

 

I have 6 or 7 boxes of Floppies for the Apple ][ and another long-term goal is to extract the files from these ~40 year old disks and move them to newer media.

[Gorgon]

Part 1: Disassembly & Cleaning

 

The case is in great shape all things considered. The Cyan splotches on it are Cuperous Oxide from when my humidifier water feed's "Vamp Clamp" started leaking right above the shelves where the Apple ][ and a bunch of modern hardware lived. That was exciting!

 

 

The case was cleaned with mild dish detergent and lots of elbow grease and came out nicely.

 

After removing a bunch of screws from the base and disconnecting the Keyboard the guts are revealed. A little dusty but none the worse for the years.

 

 

The Power Supply and motherboard were dismounted. You have to be very gentle releasing the nylon clips on the posts holding the Motherboard down as they can break if forced.

 

A dust off with a brush and a wash with soapy water and the base came out nicely with the exception of a foam ring surrounding the speaker disintegrating when touched.

 

The motherboard was gently brushed with a natural bristle brush (to avoid static from Nylon brushes) and then had the dust blown off it with Compressed Air.

 

 

The motherboard (820-0044-C) appears to have been manufactured in mid 1981 but the chip date codes tell us that it likely sat in stock with a base 16k of memory installed until mid 1983 when an additional 32k of RAM was added and it was likely sold sometime after that date.

 

It also has a factory "Bodge" (Pin3 NE555 @K13 <-> R15 (1M) & R29 (12K)) on the rear but shows no sign of rework:

 

This "Bodge" will be examined later when I dive into the Schematics to install an improved Color-Killer mod.

 

The Power Supply needs to be checked and will be dealt with separately.

 

The Keyboard was very dusty and the key caps a little grungy but nothing a brush and blow won't take care of. It is the model with Alps key switches which still have good travel and bounce.

 

The keyboard had all it's key caps removed and the bezel for the power lamp. Yes, a Lamp, a 5v, 115mA T-1 3/4 model 817 specifically. The multi-meter showed continuity on the lamp but I'm ordering spares as these "miniature" lamps are getting very rare.

 

The keyboard was gently brushed up-side down over the sink to remove accumulated dust and then cleaned with Windex on a Shop Towel. Only one very tiny rust spot on the base which I'll deal with later with some black "Rust-Coat" paint once its burnished off.

 

I'll likely hit all the switches with some DeOxit D5 later after I test the system for an initial boot.

 

The key caps soaked overnight in a bowl with some dish detergent and then the caps were gently scrubbed with a micro-fibre cloth and then rinsed with clean water and left to dry overnight.

[Gorgon]

Part 2: Power Supply Repair and Testing

 

Disclaimer: If you don't know what you are doing DO NOT open and attempt to fix or modify a Power Supply. Even disconnected from wall power they can contain hazardous voltages. new Replacement Power Supplies for Apple 2s can be found even to this day.

 

The Power Supply in the Apple 2 was revolutionary as the "Woz" and Jobs decided to go with a much smaller Switched Mode Power Supply rather than a Linear Mode models commonly found in other 8-bit systems of the day such as from Commodore and Tandy Corp.

 

In this case it is an Astek Model AA 11040B; Apple P/N 605-5703:

 

First we need to get into it. This is accomplished by drilling out the rivets at the center of the two side panels using a number drill slightly larger than the diameter of the hole and working up a few sizes until the head separates from the body and spins, usually getting wrapped around the drill bit.

 

Once opened and the strain relief bushing for the DC Leads removed (squeeze with a pair of needle-nose pliers if you don't have a releaser tool) remove the six machine screws and washers holding the circuit board to the top of the case:

 

and expose the board:

 

The board was examined looking for components with any signs of overheating and especially looking at the Electrolytic Capacitors for any bulging or signs of leakage. The bottom of the board was also inspected to check for any bad solder joints.

 

Of especial interest is the "X" Capacitor, a 0.1uF, 250V Metalized Paper "RIFA" capacitor circled above. This capacitor is installed between "Hot" and "Neutral" on the 120V "Mains" side of the Power Supply and is in-circuit to reduce any switching noise from the power supply getting back into the Mains and interfering with the operation of other devices.

 

These capacitors also help reducing the impact of any transients on the Mains from damaging the Power Supply and are designed to fail open. Somewhat like a Metal Oxide Varistor (MOV) they absorb some of a Transient's energy which blows-out some of the Metal inside of the capacitor.

 

The X Capacitor in these Power Supplies is notorious for failure. The plastic cover on them cracks over time, this allows moisture to creep into the capacitor which accelerates it's failure. When these fail they boil off the dielectric releasing noxious "fishy" fumes. As they fail open the Power Supply will still work but with less Transient protection in-bound, and more switching noise out-bound.

 

Sure enough a Visual inspection shows this 40 year old capacitor has the typical cracks in the case so it was removed.

 

Amazingly enough an exact replacement is still available. Rifa got bought out by Kemet years ago who still manufacture these.

 

Let's, however, use a more modern Metalized Polypropylene (MPP) "X" Capacitor. These have a much less smelly failure mode and though they have a lower slew rate are still rated for the same application. Fortunately, the Circuit Board has not only holes for the 0.8" spaced RIFA but additional holes for much more common 0.6" lead spacing:

 

A Kemet 275V, 0.1uF X2 MPP Capacitor was procured as a replacement.

 

In general, "X" Capacitors, which sit between Line and "Neutral", or "Line" to "Line" in 220/240V, can be replaced with "X2" or "Y" Capacitors. "Y" Capacitors, are designed to sit between "Line" and "Ground" and can ONLY be replaced with
Y" Capacitors.

 

This was ordered from DigiKey in Thief River Falls, MN and amazingly arrived in Eastern Ontario less than 24-hours later.

 

Also ordered were some of the components for the Clone Motherboard and some spare 2.5A, 250V "Mini" fuses as replacements for the existing 2.75A, 125V Medium Blow Fuse in the Power Supply, just in case, as these are an unusual size and not commonly available.

 

The circuit board and case were cleaned and special care was taken to ensure all the metal scraps from the rivet removals were removed.

 

Keeping with the Retro theme I busted out the Weller WTCP-N Soldering Iron I inherited from my late father. Older than this Power Supply but it still works like a charm and the "PT" tips are still available. Shown here with the Desoldering attachment I gave Dad for Christmas one year.

 

The replacement Capacitor was installed and the residual Rosin Flux removed with some Iso-Propyl Alcohol (IPA).

 

Now to test the Power Supply.

 

A quick test with the multi meter showed no shorts between the Common (Ground) and any of the Supply Voltages: +5, +12, -5 and -12V.

 

Powering the unit on, however, showed no voltage on any of the leads with the Power Supply out of the system. These Astec Supplies are supposed to work with no Load so what's up?

 

Connecting the unit to the motherboard and turning it on also resulted in no power light, no beep and no 5V on the TTL Logic chips.

 

Houston, we have a problem.

 

To keep the project moving forward in a timely fashion I applied $ and ordered a replacement Power Supply which should be here in a few days from Reactive Micro in the States. I was intending on doing this eventually anyway. I ordered the one with the "Universal DC Connector" which will allow its use in all of the Apple 2 Series and also provided a little more "Ummph" and a Molex and USB 5V for modding.

 

I will put the original Power Supply aside for now as I need to get a better multi-meter and possibly an Oscilloscope to repair it.

[Gorgon]

Part 3: Disk ][ Refurbishment

[Gorgon]

Part 4: System Testing

[Gorgon]

Part 5: Building up the Clone Motherboard.

 

Ordered from DigiKey:

• Most of the 7400-series TTL Integrated Circuits
• Transistors
• Power Supply, Cassette and Video Output Connectors
• 300 Ohm Potentiometer for Video Output Level
• 14.318MHz Oscillator Crystal
• 2 x 16-pin gold-plated machined DIP sockets for the Keyboard and Game I/O Connectors

Ordered from Unicorn Electronics a reseller of Vintage Parts in Aliquippa, PA:

• 6502 CPU
• 24 x 4116 150ns 8k x 1 DRAM chips
• 7 x 2716 EPROMs (The original Apple 2s used 9316, but the Clone can use 2716s or, with a mod, 2732s)
• Some of the more esoteric 7400-series TTL chips that aren't readily available: 74S86, 74S175; 74S195; 3 x 74LS367; 3 x 74LS74 and a 74166

 

[Gorgon]

Part 6: New Hardware for the Modern Age:

 

Ordered from eBay:

• A SASI Controller for the Sider 10MB Hard Disk, built from the original design with NOS ROMs. The Seller (Thanks Lee!), included a 50-pin cable to go from the card to the outside of the chassis and a SASI Terminator I was missing for the Sider unit itself.
• A tested Apple 2 Super Serial Card. This system had one originally, I have the manual for it, and it's useful to have, for example, to connect an external computer to the Apple via RS-232.

Ordered from Big Mess O' Wires:

• A Floppy EMU Model C. This hardware can emulate multiple Apple 2 140kB Disk ][ drives and/or a UniDisk Hard Drive up to 32MB under ProDOS using up to a 32GB Micro SD Card. Mounting the SD Card in a PC allows copying Disk Images back and forth.
• Various adapters: A/B Switch; Daisy Chainer Disk Coupler and a Dual 5.25 Drive Adapter. These will allow me flexibility to chain drives together and switch between them.
• A Yellowstone Universal Disk Controller, This will allow the use of an Apple 3.5" Floppy under ProDOS and other features to improve the quality of life.

Ordered from RetroTink:

• A RetroTink 2X Pro. This will convert the 320x200 Composite Video Output from the Apple 2 to HDMI for use on a modern Display. I may look at getting a Native VGA Card for the Apple 2 eventually but these are super handy for use not only for Retro Computers but for Old School Gaming Systems so I ordered another for the kids to use with their N64s etc. as they are big into emulation this will allow them to also experience old consoles on the big Panel in the Rec Room.

[Gorgon]

Part 7: Putting it All Together.

 

Install Clone Motherboard in Vintage Apple II Chassis.

Install Super Serial, SASI, Yellowstone Controllers as well as Language Card and RAM Expansion.