rnd:projects:a2rest

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rnd:projects:a2rest [2024-03-13 19:39] – created asdfrnd:projects:a2rest [2024-08-24 02:30] (current) – asdf
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 ====== Apple II restoration ====== ====== Apple II restoration ======
-It's hard to believe, but we're now in possession of a real [[:histcomp:Apple II]]! Specifically, an Apple IIe with two Disk II drives. Since it hasn't been used for at least 25 years (and has been sitting in an uninsulated garage for an unknown proportion of that time), it's in need of some minor cleaning and repair before we turn it on again. Fortunately, the PCBs all look easy enough to work on once we have sufficient practice desoldering. +It's hard to believe, but we're now in possession of a real [[:histcomp:Apple II]]! Specifically, an enhanced Apple IIe with two Disk II drives. Since it hasn't been used for at least 25 years (and has been sitting in an uninsulated garage for an unknown proportion of that time), it's in need of some minor cleaning and repair before we turn it on again. Fortunately, the PCBs all look easy enough to work on once we have sufficient practice desoldering.  
 + 
 +===== Inspection ===== 
 +The outer shell is unsurprisingly yellowed and dusty. The screws holding the shell together are missing, so be cautious when handling the machine.  
 + 
 +The interior is likewise dusty. The base has small spots that appear to be corrosion from animal droppings. The name "Schrock" is written below the power supply in permanent ink; it's not clear whether it's from a previous owner, a service agent, or an Apple engineer.  
 + 
 +Below the coating of dust, the main board is remarkably well-labelled and cleanly laid out. Important ICs are given not just part numbers but function labels ("video ROM", "keyboard ROM", "MMU", etc.) as well. It truly is an artifact from a different time in Apple's history. The board layout alone makes it clear that users were meant to access the innards. The CPU is a [[wp>WDC_65C02#65SC02|65SC02]], a version of the 65C02 without ''BIT'' instructions. It's possible that this machine was not upgraded using the official enhancement kit((https://ancientelectronics.wordpress.com/2021/04/17/apple-enhanced-iie/)). We might want to replace it with a more fully-featured 65C02((https://www.mouser.com/ProductDetail/Western-Design-Center-WDC/W65C02S6TPG-14?qs=opBjA1TV903lvWo9AEKH5w%3D%3D&mgh=1&utm_id=17222215321&gad_source=1&gclid=EAIaIQobChMItKKi_YuHiAMVtxatBh0TZg2QEAQYAiABEgLDnPD_BwE)). Header J18 is for the speaker. 
 + 
 +There are four expansion cards installed. The aux connector slot has an extended 80 column/64K expansion card. Slot 1 contains a Super Serial card connected to a DB-25 port on the rear panel. Slot 4 contains a revised Applied Engineering RAMFactor card((https://ae.applearchives.com/all_apple_iis/ramfactor/)). Finally, the Disk II interface card is in slot 6. It's worth noting that while the Disk II headers are neither shrouded nor keyed, it is effectively impossible to connect the ribbon cables backwards because the headers run parallel to the board. That is fantastic attention to detail.  
 + 
 +The PSU includes a label showing the power connector pinout, another indicator of of a bygone era of Apple engineering. This diagram is of the **motherboard power socket**.  
 + 
 +  * pin 1 (black): ground 
 +  * pin 2 (black): ground 
 +  * pin 3 (orange): +5 V, 2.5 A 
 +  * pin 4 (yellow): +12 V, 1.5 A 
 +  * pin 5 (green): -12 V, 0.25 A 
 +  * pin 6 (blue): -5 V, 0.25 A 
 + 
 +The large blue capacitors inside the PSU are bulging slightly.  
 + 
 +Both Disk II drives are labelled "Drive 1". One has "Peters" scratched into it, so we shall refer to it as the Peters drive. The drive belts are accessible by removing the bottom panel, which can only be unscrewed once the top panel has been removed. Removing the bottom panel is also the easiest way to access the lower of two PCBs contained inside. Those circuit boards differ slightly between the two drives. Both drives' belts seem fine, and their shutter mechanisms are quite springy. The ribbon cable on the Peters drive was connected so that the red stripe aligned with pins 19 and 20, which looks incorrect at a glance. The other drive's motor connector was disconnected when we opened it. The Peters drive was missing one outer screw 
 + 
 +The following electrolytic capacitors should be replaced for safety before attempting to power up the machine(([[https://www.youtube.com/watch?v=EJ0IKmHAfoA|This video]] claims that it's not //always// necessary, but I'm going to do it anyway.)): 
 + 
 +  * motherboard 
 +    * C8 (A13): axial 10 uF, 16 V, 12 mm L, 6 mm D 
 +    * C9 (A1): axial 10 uF, 16 V, 12 mm L, 6 mm D 
 +    * C12: axial 10 uF, 16 V, 12 mm L, 6 mm D 
 +    * C15: axial 10 uF, 16 V, 12 mm L, 6 mm D 
 +    * C17: axial ? uF, ? V, 12 mm L, 6 mm D 
 +    * C53: axial 10 uF, 16 V, 12 mm L, 6 mm D 
 +    * C54 (C6): axial 10 uF, 16 V, 12 mm L, 6 mm D 
 +    * C72 (E14): axial ? uF, ? V, 12 mm L, 6 mm D 
 +    * C82 (F3): axial 10 uF, 16 V, 12 mm L, 6 mm D 
 +  * power supply 
 +    * C1: 100 nF X2 class, 20.3 mm pitch, 7 mm W 
 +    * C5: radial 47 uF, 250 V, 33 mm H, 18.5 mm D, pitch ?  
 +    * C6: radial 47 uF, 250 V, 33 mm H, 18.5 mm D, pitch ? 
 +    * C7: radial 220 uF, 10V, 22 mm H, 10 mm D, pitch ? 
 +    * C12: radial 1000 uF, 10 V, 42 mm H, 13 mm D, pitch ? 
 +    * C13: radial 1000 uF, 10 V, 42 mm H, 13 mm D, pitch ? 
 +    * C14: radial 1000 uF, 10 V, 42 mm H, 13 mm D, pitch ? 
 +    * C15: radial 220 uF, 10 V, 21.9 mm H, 10 mm D, pitch ? 
 +    * C16: radial 220 uF, 10 V, 21.9 mm H, 10 mm D, pitch ? 
 +    * C19: radial 1000 uF, 10 V, 42 mm H, 13 mm D, pitch ? 
 +    * C20: radial 680 uF, 16 V, 42 mm H, 13 mm D, pitch ? 
 +    * C21: radial 330 uF, 16 V, 21 mm H, 10 mm D, pitch ? 
 +    * C22: radial 330 uF, 16 V, 23.5 mm H, 13 mm D 
 +    * C24: radial 47 uF, 250 V, 33 mm H, 18.5 mm D, pitch 8 mm  
 +    * C25: radial 47 uF, 250, 33 mm H, 18.5 mm D, pitch 8 mm 
 +  * Disk II interface card 
 +    * C2: axial 22 uF, 16 V 
 +  * RAMFactor (no part labels) 
 +    * axial 1000 uF, 10 V, 20 mm L, 10 mm D 
 +    * 2x axial 10 uF, 16 V, 12 mm L, 6 mm D 
 +  * Peters drive analog board 
 +    * C2: axial ? uF, ? V, 16 mm L, 13 mm D 
 +    * C4: axial 470 uF, 6.3 V, 20 mm L, 13 mm D 
 +    * C5: axial 10 uF, 16 V, 12 mm L, 5 mm D 
 +  * Peters drive lower board 
 +    * C1 axial 4.7 uF, 35 V, 12 mm L, 5.6 mm D 
 +    * C7?  
 +    * C8: axial 220 uF, 16 V, 20 mm L, 11? mm D 
 +  * non-Peters drive analog board 
 +    * C2: axial ? uF, ? V, 22 mm L, 6 mm D 
 +    * C4: axial 470 uF, 6.3 V, 16 mm L, 4 mm D 
 +    * C5: axial 10 uF, 10 V, 13 mm L, 5 mm D 
 +  * non-Peters drive lower board 
 +    * C1: axial 10 uF, 35 V, 15 mm L, 5 mm D 
 +    * C5: axial 10 uF, 35 V, 15 mm L, 5 mm D 
 +    * C6: axial 10 uF, 35 V, 15 mm L, 5 mm D 
 + 
 +We wish to comment once again upon the ease with which we could disassemble and, more importantly, reassemble the computer and drives. It is not at all difficult to see why the Apple II line had such longevity.  
 + 
 +===== Cleaning ===== 
 +We dusted all PCBs with a Pacific Arc BR-110 anti-static brush.  
 + 
 +===== Component replacements ===== 
 +==== Power supply ==== 
 + 
 + 
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