Original Sun Remarketing Apple III Parts
We are the world's original Apple III dealer. Browse our eBay store for motherboards, power supplies, drives, keyboards, and complete systems from our inventory.
Sun Remarketing & the Apple III — Our Deepest Connection
No company on earth knows the Apple III like Sun Remarketing. When Apple discontinued the Apple III in 1984, they chose Sun Remarketing to handle the remaining inventory. We received thousands of Apple III units — factory-new, refurbished, and service stock — and became the world's largest dealer of Apple III computers. We refurbished, tested, sold, and supported these machines for years, shipping them to businesses, schools, and collectors across the country. Our technicians have opened, diagnosed, and repaired more Apple IIIs than anyone. This guide draws directly on that unparalleled hands-on experience spanning over four decades.
In This Guide
1. Overview & History
Difficulty:
Medium-Hard
The Apple III was Apple's first attempt at a business computer, announced in May 1980 and intended to compete with the IBM PC in the corporate market. It was designed to succeed the wildly popular Apple II while maintaining backward compatibility — you could run Apple II software in emulation mode. On paper, it was an impressive machine: a 2 MHz Synertek 6502B processor, up to 512KB of RAM (enormous for 1980), a built-in 5.25" floppy drive, and a sophisticated new operating system called SOS (Sophisticated Operating System).
But the Apple III's launch was a disaster. Steve Jobs reportedly insisted that the machine have no cooling fan — he considered fans inelegant and noisy. The engineering team was forced to rely on the aluminum chassis as a heat sink, casting the base of the case to conduct heat away from the components. In theory, this was clever. In practice, it was catastrophic.
The Recall
The combination of inadequate cooling, tight component spacing, and manufacturing tolerances led to widespread failures within months of launch. Chips literally worked themselves loose from their sockets as the motherboard expanded and contracted through thermal cycles. Solder joints cracked. The real-time clock chip, a custom component that Apple had designed specifically for the III, failed at alarming rates. Apple was forced to recall the first 14,000 units — virtually the entire production run — and replace the motherboards.
The Revised Apple III
Apple re-released the Apple III in late 1981 with a revised motherboard that addressed many of the thermal issues. In December 1983, they released the Apple III Plus with a built-in clock, improved power supply, new keyboard, and 256KB of RAM standard. But the damage was done. The business market had lost confidence, and IBM's PC was gaining unstoppable momentum. Apple discontinued the entire Apple III line in April 1984, having sold approximately 65,000–75,000 units total.
Why the Apple III Matters
Despite its troubled history, the Apple III is a genuinely important computer. It introduced technologies that would appear in the Macintosh years later. Its SOS operating system was remarkably advanced — a device-driver-based, memory-mapped system that influenced Apple's later OS designs. The ProFile hard drive, first sold as an Apple III peripheral, was Apple's first-ever hard drive product. And the machine itself, when working properly, is a fast, capable, and beautifully built piece of hardware. It deserves better than its reputation.
From Our Archives
When Apple shipped us their remaining Apple III inventory, we received not just complete systems but also pallets of spare motherboards, power supplies, drives, keyboards, and documentation. Our technicians developed standardized procedures for diagnosing and repairing every known Apple III failure mode. Many of the tips in this guide come directly from those internal service notes, refined over thousands of repairs.
2. The Infamous Chip Creep Problem
Difficulty:
Medium
If you know one thing about the Apple III, it is probably this: the chips fall out. This is not an exaggeration. The phenomenon, known as "chip creep," was the single most common failure mode of the original Apple III and the primary reason for the 1981 recall.
What Causes Chip Creep
The original Apple III had no internal fan. Heat from the CPU, RAM, and support chips was supposed to dissipate through the cast aluminum case bottom. But the case could not shed heat fast enough during sustained use. The motherboard and its IC sockets expanded as temperatures rose, then contracted as the machine cooled. Over dozens of power cycles, this thermal cycling gradually worked the DIP (Dual Inline Package) chips upward out of their sockets — sometimes by just a fraction of a millimeter, sometimes enough to visibly lift pins out of contact.
The result was intermittent failures, random crashes, garbled displays, and eventually a completely dead machine. Apple's official recommendation to frustrated owners became legendary: "Lift the front of the Apple III six inches off the desk and drop it." The impact was supposed to reseat the chips. It sometimes worked — temporarily.
⚠ Do Not Drop Your Apple III
While the "lift and drop" method is a famous piece of Apple lore, we strongly advise against it. Dropping the machine risks cracking solder joints, damaging the floppy drive mechanism, and stressing the motherboard. The proper fix takes more time but actually solves the problem.
The Proper Chip Reseat Procedure
1
Open the Case & Access the Motherboard
Unplug the Apple III and remove all cables. Turn the unit upside-down and remove the four Phillips screws at the corners of the base plate. Carefully lift the base (which contains the motherboard) away from the top case. Disconnect the keyboard ribbon cable and the speaker wire. Set the top case aside — the motherboard is now fully accessible.
⏲ Estimated time: 15 minutes
2
Identify All Socketed ICs
The Apple III motherboard has a large number of socketed chips: the 6502B CPU, the ROM chips, all RAM ICs, the system controller, the real-time clock chip, and various TTL glue logic. On a standard Apple III board, you are looking at 40–60+ socketed ICs. Every single one of them is a candidate for chip creep. Visually inspect each chip — if you can see any daylight between the chip body and the socket, that chip has crept.
⏲ Estimated time: 15 minutes
3
Remove, Clean, and Reseat Every Chip
Using a proper IC extraction tool (not a flathead screwdriver — you will bend pins), carefully remove each socketed chip. Work one chip at a time so you do not mix up positions. Clean the pins with a fiberglass pen or by drawing them across a piece of fine emery cloth. Apply a light coat of DeoxIT or similar contact cleaner to the pins. Then firmly press the chip back into its socket, ensuring all pins are aligned and fully seated. You should feel the chip snap into place.
This is tedious work, but it is the single most effective repair you can perform on an Apple III. At Sun Remarketing, this was the first step in every Apple III service procedure, and it resolved the majority of dead-on-arrival machines we received from Apple's inventory.
⏲ Estimated time: 2–3 hours
4
Consider Socket Replacement (Advanced)
If you find chips that repeatedly creep after reseating, the socket itself may be worn. Low-quality sockets with loose grip were a contributing factor in the original Apple III failures. For critical ICs (CPU, ROM), consider desoldering the old socket and replacing it with a high-quality machined-pin socket. These grip the IC pins much more firmly and resist thermal creep. This is a more advanced repair requiring good soldering skills and a desoldering station.
⏲ Estimated time: 30–45 minutes per socket
💡 Tip: The Revised Board Is Better, Not Immune
The revised Apple III motherboard (1981) and the Apple III Plus board improved thermal management and used better sockets, but chip creep can still occur after 40+ years. Even if you have a later-model Apple III, perform the full reseat procedure. It is cheap insurance.
3. Power Supply Service
Difficulty:
Medium-Hard
The Apple III power supply is a linear supply in the original model and a switching supply in the Apple III Plus. Both are now over 40 years old and require service before you can safely power on the machine. A failing power supply can send incorrect voltages to the motherboard and destroy irreplaceable components.
⚠ Mains Voltage Danger
The Apple III power supply operates at mains voltage (120/240V AC). Capacitors inside can hold a lethal charge even after the machine is unplugged. Always discharge filter capacitors before working inside the PSU. If you are not comfortable working with mains-voltage electronics, have the power supply serviced by someone with experience.
5
Remove & Visually Inspect the PSU
With the case open and the motherboard accessible, disconnect the power supply connectors from the motherboard. The Apple III PSU is mounted in the rear-left of the chassis. Remove the mounting screws and carefully lift it out. Inspect both sides of the PCB: look for bulging or leaking electrolytic capacitors (brown crust at the base), darkened or cracked resistors, and any signs of overheating (discolored PCB areas).
⏲ Estimated time: 20 minutes
6
Replace the RIFA Line-Filter Capacitors
This is the most urgent repair. The RIFA paper-film capacitors (the rectangular yellow or brown components near the AC inlet) are infamous for failing spectacularly. Over decades, moisture penetrates the epoxy casing, and when the capacitor is energized, it can explode with a loud pop, a flash, and a cloud of acrid smoke. Inspect your RIFAs closely — if the epoxy shows any hairline cracks (and after 40 years, it almost certainly does), replace them immediately. Use modern X2-rated safety capacitors of the same value, typically 0.1uF or 0.047uF at 275VAC.
⏲ Estimated time: 30 minutes
7
Full Electrolytic Capacitor Replacement
Replace every electrolytic capacitor in the power supply with a modern equivalent. Match the capacitance and use the same or higher voltage rating. Use 105°C-rated capacitors for maximum longevity. The Apple III PSU typically contains 10–15 electrolytics. Pay special attention to the main filter capacitors (the large ones) — these are most likely to have drifted out of spec or developed high ESR (Equivalent Series Resistance), which causes voltage ripple and instability.
⏲ Estimated time: 1.5–2.5 hours
8
Test Voltage Rails Before Reconnecting
Before connecting the PSU back to the motherboard, power it on with an appropriate load and measure all output rails with a multimeter. The Apple III requires +5V, +12V, -5V, and -12V. All should be within 5% of their rated values. Also check for excessive AC ripple on the DC rails using an oscilloscope if available. A recapped PSU with good voltages is safe to reconnect to the motherboard.
⏲ Estimated time: 30 minutes
4. Motherboard Troubleshooting
Difficulty:
Medium-Hard
If you have reseated all chips and verified the power supply but the Apple III still does not work, the motherboard itself requires deeper diagnosis. The Apple III motherboard is a complex board with several known weak points.
The Real-Time Clock Chip
The Apple III uses a custom real-time clock (RTC) chip — the MM58167 or equivalent — that maintains the system clock and calendar. This chip has a high failure rate. When it fails, the Apple III may refuse to boot, display a "RETRY" error, or behave erratically. The RTC is socketed on most boards, so replacement is straightforward if you can find the part. The MM58167 is no longer manufactured, but NOS (New Old Stock) chips turn up on eBay regularly. Some Apple III owners have also built adapter boards that allow a modern RTC module to substitute for the original chip.
9
Diagnose the RTC
If your Apple III powers on but fails to boot or shows clock-related errors, the RTC is suspect. Remove the RTC chip from its socket and attempt to boot without it. Some Apple III software can operate without a functioning clock (you will simply not have date/time stamping). If the machine boots with the RTC removed, you have confirmed the RTC as the problem. Source a replacement MM58167 and install it.
⏲ Estimated time: 30 minutes
RAM Diagnosis
The Apple III shipped with 128KB or 256KB of RAM (expandable to 512KB), using banks of 4164 or 41256 DRAM chips in DIP packages. RAM failure causes a range of symptoms: failure to boot, random characters on screen, crashes during operation, or specific memory-test failures.
10
Systematic RAM Testing
The Apple III has a built-in self-test that runs at power-on. If the self-test detects a RAM error, it will display an error code that indicates which bank and bit have failed. Consult the Apple III Technical Reference Manual for the error code chart. Once you have identified the failed chip, replace it with a known-good 4164 (for 128KB/256KB boards) or 41256 DRAM. These chips are still readily available and inexpensive. If you do not get an error code (the machine just sits dark), try removing all but the minimum required RAM banks and testing one bank at a time.
⏲ Estimated time: 1–2 hours
ROM Issues
The Apple III's boot ROMs contain the system firmware and initial self-test code. Corrupted or failed ROM chips will prevent the machine from doing anything at all — no beep, no display, no sign of life. If you have verified the power supply is good and all chips are properly seated but the machine is completely inert, the ROMs are a prime suspect. ROM chips can be read and verified with an EPROM programmer. Replacement ROM sets are available from the vintage Apple community, and you can burn your own using the publicly available ROM images and compatible EPROM chips (e.g., 2764 or 27128).
11
Verify & Replace ROMs
Remove each ROM chip, read it with an EPROM programmer, and compare the contents against known-good ROM dumps (available from various Apple III archive sites). If any ROM does not match, the data has become corrupted — a common failure mode for older EPROMs that have been exposed to UV light through their quartz windows over decades. Burn replacements onto fresh 2764 or 27128 EPROMs, apply an opaque label over the UV window, and install.
⏲ Estimated time: 1–2 hours (requires EPROM programmer)
💡 The Motherboard Battery
Some Apple III models include a small battery to maintain RTC and parameter RAM settings when powered off. If this battery has leaked, inspect the surrounding PCB area for corrosion. Clean with 99% IPA and a soft brush. If traces are damaged, you may need to repair them with fine wire. Remove the old battery and either replace it with a modern equivalent or install a battery holder so it can be easily swapped in the future.
5. The Apple III ProFile Hard Drive
Difficulty:
Medium-Hard
The Apple ProFile, introduced in September 1981, was Apple's very first hard drive product. It was designed primarily as a companion for the Apple III, connecting via a dedicated parallel interface card. The ProFile provided a then-astounding 5MB of storage (a 10MB version came later) in a hefty external enclosure that sat on top of or beside the Apple III.
The ProFile used a Seagate ST-506 mechanism — the same 5.25" full-height drive that powered many early hard disk systems. Apple added their own controller board and a distinctive beige enclosure with a front-panel LED. The ProFile connected to the Apple III via a DB-25 parallel cable and a dedicated ProFile interface card installed in one of the Apple III's four expansion slots.
Common ProFile Failures
After 40+ years, most ProFiles have one or more of the following issues:
- Seized spindle motor: The drive motor may not spin up at all. Sometimes a gentle nudge to the spindle (with the drive powered on) can break the stiction, but this is risky.
- Degraded drive belt: Early ST-506 mechanisms use a rubber belt to couple the spindle motor to the platters. This belt stretches, hardens, or breaks over time. Belt replacement is the most common ProFile repair.
- Head contamination: The read/write heads can accumulate oxide residue from the aging media, causing read errors or head crashes.
- Controller board failure: Apple's ProFile controller board uses its own set of capacitors and ICs that can fail with age.
12
Belt Replacement
Open the ProFile enclosure by removing the screws on the rear panel and sliding the case off. Locate the drive belt connecting the spindle motor pulley to the platter hub. If the belt is stretched, cracked, or gummy, it must be replaced. Remove the old belt (it may have turned to goo — clean all residue with IPA). Install a new belt of the correct size and tension. Replacement belts for the ST-506 are available from vintage computer parts suppliers and some general-purpose belt vendors. The correct belt is typically a flat rubber belt approximately 3.5" in circumference.
⏲ Estimated time: 1–2 hours
13
Head Cleaning
If the drive spins up but produces read errors, the heads may be contaminated. This is a delicate operation. With the drive powered off and the top cover of the drive mechanism removed (in a clean, dust-free environment), use a lint-free swab dampened with 99% IPA to gently clean each head surface. Do not apply pressure — the heads are fragile. Allow the IPA to fully evaporate before reassembling. If you are uncomfortable working with bare hard drive platters and heads, this may be a job for someone with data-recovery experience.
⏲ Estimated time: 45 minutes
14
Modern Alternatives: ProFile Emulators
Given the fragility of 40-year-old hard drives, many Apple III owners have moved to modern solid-state ProFile emulators. Devices like the IDEfile and the X/ProFile use compact flash cards or SD cards to emulate a ProFile, connecting to the same parallel interface card. These are far more reliable than an original ProFile and can even store multiple disk images. If your goal is a working, usable Apple III system (rather than a 100% original museum piece), a ProFile emulator is the most practical path.
⏲ Estimated time: 30 minutes to install
Sun Remarketing & the ProFile
Sun Remarketing sold hundreds of ProFile drives alongside our Apple III systems. We received ProFiles as part of Apple's inventory transfers, and our techs became experts at reviving them. The ProFile was often bundled with our refurbished Apple III packages — a complete business workstation. We still occasionally encounter ProFile drives in our remaining parts inventory.
6. Keyboard & Case Restoration
Difficulty:
Easy
The Apple III keyboard is one of the machine's genuine bright spots. Unlike the Apple II's somewhat toy-like keyboard, the Apple III features a full-size, professional-grade keyboard with a built-in numeric keypad — a feature that underscored its business ambitions. The keyboard has a solid, satisfying feel and uses a high-quality key mechanism. The Apple III Plus further improved the keyboard with an even better tactile response and a more refined layout.
Keyboard Cleaning
15
Deep-Clean the Keyboard
Disconnect the keyboard ribbon cable from the motherboard. Remove all keycaps using a keycap puller (work gently — the stems on 1980s keyboards can be brittle). Soak the keycaps in warm water with a small amount of dish soap. While the keycaps soak, clean the keyboard PCB and key mechanisms with compressed air to remove dust and debris. Use a soft brush dampened with IPA to clean around each switch. For stubborn grime, cotton swabs dipped in IPA work well. Rinse and thoroughly dry the keycaps before reinstalling.
⏲ Estimated time: 1–2 hours
16
Keyboard Encoder & Connector
The Apple III keyboard communicates with the motherboard via a ribbon cable and an encoder circuit inside the keyboard housing. If specific keys are dead or producing wrong characters, the encoder IC may be failing, or (more likely) the ribbon cable connector has oxidized. Clean the ribbon cable contacts with a pencil eraser (yes, really — the mild abrasive removes oxide without damaging the contacts) followed by IPA. If the ribbon cable itself is damaged, replacements can be fabricated from standard FFC (Flat Flexible Cable) stock of the same pitch and pin count.
⏲ Estimated time: 30 minutes
Case Restoration
The Apple III case is a well-built two-piece design with a distinctive profile. The upper case (which houses the keyboard in the original Apple III) is painted metal, and the lower base is cast aluminum. Common cosmetic issues include paint chips, scratches, and yellowing of any plastic components.
- Paint touch-up: Small chips can be touched up with color-matched enamel paint. For a full respray, use a high-quality primer and color-matched paint (Apple's beige varied slightly between production runs).
- Aluminum base: The cast aluminum base can be cleaned with a mild aluminum polish. Do not use abrasive compounds — the casting has a specific surface texture that you want to preserve.
- Badge and labels: The Apple III has a front badge and various rear labels. Clean these gently with a damp cloth. Do not use solvents — the printing on the labels is solvent-sensitive.
7. Software & Boot
Difficulty:
Medium
With the hardware restored, you need software to make your Apple III useful. The Apple III ran its own operating system, SOS (Sophisticated Operating System), and could also emulate an Apple II for backward compatibility.
SOS — Sophisticated Operating System
SOS was remarkably advanced for 1980. It used a device-driver architecture that abstracted hardware access, supported hierarchical file systems, and provided a consistent API for applications. SOS was not a command-line OS — it booted directly into whatever application was on the boot disk. The OS itself was invisible to the user, working behind the scenes to manage memory, devices, and file I/O.
SOS version 1.3 is the final and most stable release. To boot SOS, you need a boot disk with the SOS kernel, a SOS driver file configured for your specific hardware (which peripherals are installed), and an application. The most common boot configuration is SOS with Apple III Business BASIC — a powerful, extended BASIC interpreter that was the primary development and productivity environment for the Apple III.
17
Create a Boot Disk
If you do not have original Apple III software on floppy, you will need to create boot disks from disk images. The Apple III uses standard 5.25" single-sided, single-density (140KB) floppy disks — the same physical format as Apple II disks. You can write Apple III disk images using an Apple II with a Disk II controller, or using a modern USB floppy solution like the Applesauce or a KryoFlux. ADTPro (Apple Disk Transfer ProDOS) can also be used with an Apple II in the loop. Disk images for SOS, Business BASIC, and many Apple III applications are available from archive sites like apple3.org.
⏲ Estimated time: 1–2 hours
18
First Boot & System Configuration
Insert your SOS boot disk into the internal floppy drive and power on the Apple III. If all hardware is working, you should see the drive activity light come on, hear the drive spin up and seek, and within 15–30 seconds, the SOS application (typically Business BASIC) should appear on screen. If you have a ProFile or ProFile emulator, you can install SOS onto it for faster boots and more storage. The Apple III System Utilities disk allows you to format the ProFile, install SOS, and configure device drivers.
⏲ Estimated time: 30 minutes to 1 hour
Apple II Emulation Mode
The Apple III can emulate an Apple II by booting a special "Apple II Emulation" disk. This switches the 6502B into a compatibility mode that mimics the Apple II's memory map and I/O. In emulation mode, the Apple III can run most Apple II software, giving you access to the vast Apple II software library. The emulation is not perfect — programs that rely on precise timing or access hardware directly may not work — but most productivity and game software runs fine.
💡 Essential Apple III Software
SOS 1.3 — the final OS release, most stable. Business BASIC — the primary programming environment. Apple III System Utilities — for disk formatting, driver configuration, and ProFile management. Apple Writer III — a capable word processor. VisiCalc III — the spreadsheet that defined the personal computer revolution, in its Apple III edition. All of these are available as disk images from community archives.
8. Parts Sourcing Guide
Apple III parts are scarce but not impossible to find. Here are the key components and where to source them:
| Part | Est. Cost | Where to Buy |
|---|---|---|
| PSU capacitor recap kit | $15–30 | |
| RIFA X2 safety capacitors | $4–10 | |
| 4164 DRAM chips (RAM) | $1–3 per chip | |
| MM58167 RTC chip (NOS) | $10–30 | |
| ProFile drive belt (ST-506) | $5–12 | |
| ProFile emulator (IDEfile / X/ProFile) | $80–150 | |
| Machined-pin IC sockets (various sizes) | $0.50–3 each | |
| Keyboard keycaps / parts | $10–40 | |
| 5.25" floppy disks (SSDD) | $8–20 (box of 10) | |
| DeoxIT contact cleaner | $8–15 | |
| Original Apple III parts (boards, drives, cases) | Varies widely |
A Machine Worth Saving
The Apple III gets a bad reputation, and some of it is deserved — the early manufacturing problems were real. But the Apple III that emerged after the recall was a genuinely good computer. At Sun Remarketing, we sold thousands of them to satisfied customers who used them daily for years. The Apple III was not a failure of vision; it was a failure of execution that Apple eventually corrected. Every working Apple III today is proof that the machine's design was sound. If you have one, it is worth the effort to bring it back to life.
Affiliate Disclosure: Sun Remarketing is reader-supported. When you buy through links on our site, we may earn an affiliate commission at no additional cost to you. We also sell original Apple III parts directly through our eBay store. Read our full disclosure.