This time in the Attic is a venerable, original Apple ][ from 1977. The state of the machine upon arrival wasn't catastrophic, but required a lot of attention motivated by the historic significance and rarity of this unit.
As you can see in the photos below, the case had been bored with multiple holes for the addition of an extra switch (three holes), an extra LED (one hole), and a grill for an extra speaker (nine extra holes on the side of the case). The machine was dirty, but that goes without saying. The Power Supply Unit (PSU) wasn't working (produced no voltages), and neither was the motherboard. I therefore couldn't immediately test the keyboard, but later found out that several keys weren't working either. The PSU had also been fitted with an after-market and glaringly inappropriate on-off switch that looked nothing like Apple's original.
In the photos below, the serial numbers of both the chassis and PSU are shown.
The PSU in this system was the very first volume production model designed by Apple and made by Astec: the AA11040. These aren't reliable PSUs, but rather finicky and unstable instead. They require delicate fine-tuning and matching across components to oscillate at all. In my personal view, it isn't worth the effort, cost, or risk to rebuild and recalibrate them. It will at least take a lot of time and money (including some specialised calibration equipment), and still risk the rest of your system if the PSU fails with overvoltage.
I therefore removed the guts of the PSU (carefully storing it for documentation purposes) and replaced it with a reliable, dependable modern version made for Apple ][ units. With the exception of the on-off switch, which wasn't original and didn't fit the enclosure (see the first row of photos above), the other sockets and switches were preserved, as was the DC cable harness. This way, from the outside, the PSU looks the same as the original, preserving the looks of the machine even if one opens the top lid. The ugly after-market on-off switch was replaced with a brand-new, modern one that perfectly fits the original hole in the enclosure and looks very similar to the original switch.
The keyboard assembly is an extremely rare ASSY 01-0425, to my knowledge the very first volume keyboard used in Apple ][ systems. I have never seen another unit as early as this, and thus was motivated to save it from its deplorable state, shown in the photos below.
Here is what I did to the keyboard assembly:
- All keycaps were removed and washed in soap and water;
- Every single key switch was desoldered, cleaned, lubricated and tested off circuit;
- Of the five key switches that tested bad, four were revived after a quick dip in IPA and a 1/2-hour ultrasonic cleaning cycle;
- One key switch, which resisted all attempts at being revived, was replaced with a working one;
- All discrete ICs were removed, socketed, and preemptively replaced with modern parts to minimise any future need to remove the keyboard assembly for repairs (which can always lead to damage if not done carefully);
- With the board freed from switches, the PCB was thoroughly cleaned with electronics detergent, and only then were the key switches soldered back in;
- The electrolytic capacitors were replaced with high-quality modern parts;
- One damaged ceramic cap was also replaced;
- The keyboard decoding chip (an exceedingly rare custom part that is practically impossible to obtain today) was fitted with a heatsink, even though it doesn't run hot, as an attempt to extend its life as much as possible;
- The original 40-pin socket of the decoding chip (a corroded single-wipe unit) was replaced with a brand-new, double-wipe part that is more reliable;
- Corrosion on the metal bars that give the keyboard assembly strength was treated with rust converter. The spots where rust was removed became dark purple, which is desirable: the purple compound is inert and protects the vulnerable spot from future corrosion.
The motherboard was in fair condition, as can be seen in the photos below.
Here is what I did to restore it to mint condition:
- Every IC was removed and tested off-circuit. Regrettably, all the beautiful ceramic-packaged DRAM chips tested bad and were replaced with very reliable, New-Old-Stock (NOS) TI parts with date codes of late 1983. Only one 74-series IC tested bad and was replaced with a modern equivalent;
- I moved the excellent NEC-branded DRAM chips (which were all working) to the second memory bank, where they will be less stressed, and populated the first bank with the robust, NOS TI parts;
- With all ICs removed, the board was washed with distilled water and neutral soap;
- All sockets, slots and connectors were cleaned and lubricated with DeoxIT D5;
- One of the sockets, upon inspection with a microscope, was discovered to have a broken inner contact. That socket was replaced with a modern double-wipe unit;
- The RCA video connector was preemptively reinforced with solder to prevent the cilinder from becoming detached from its chassis, which is a common fault;
- Original non-LS-series ICs that have modern LS-series equivalents were preemptively replaced with brand-new modern equivalents in an effort to reduce excess heat, power dissipation, and preemptively remove common points of (future) failure;
- Non-LS-series ICs that don't have modern equivalents were fitted with heatsinks to reduce their running temperature and prolong their lives;
- Original LS-series ICs that were running abnormally hot were preemptively replaced;
- The CPU and two of the ROMs, observed to run at above 50 degrees Celsius, were also fitted with heatsinks.
The initial result of the motherboard's restoration can be seen in the photos below. After stress-testing it and taking more temperature measurements, I added more heatsinks, as discussed above. Photos of the very final result are shown at the end of this post.
To make the system more easily usable in this day and age, I've added three modern boards to expansion slots: a modern 16KB RAM expansion (bringing the system to a total of 64KB), a modern VGA color card, and a modern EPROM board (featuring ProDOS, utilities, and a number of games) that replaces old disk drives.
In the photos below, the system is shown running a few games.
The case required a fair bit of work:
- All parts were thoroughly washed;
- Unoriginal holes (13 in total) were filled with plastic epoxy putty;
- The original paint (which was chipped, scratched, scuffed, and generally in very poor condition) was sanded down and the parts resprayed with multiple layers of paint and matt varnish. Now one can no longer see where the unoriginal holes had been drilled, as the new finish is seamless;
- As a final step, the case was protected with Renaissance conservation wax.
The next photos below show the system after restoration, with the top lid removed so the internals can be seen. Notice, in the detail shown in the central photo of the middle row, how no vestiges are left of the unoriginal holes (for the added switch and LED, as can be seen in the very first collage of photos above).
Finally, here are some impressions of the final result:
High-resolution, non-cropped versions of the photos above can be found in the Github repository of this restoration.