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Atari 1020 Capacitor Replacement Guide

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Atari 1020 with the top cover removed

The Atari 1020 Color Printer has five aluminium electrolytic capacitors on its board. The largest is the main filter after the bridge rectifier; two more sit on the outputs of the two 5 V regulators, and two on the reset pins of the microcontrollers.[1] All values and ratings below are from Atari's schematic in the field service manual.

Capacitor list

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Atari 1020 electrolytic capacitors (FD100288 figure 2-2)
Ref Value Voltage Where it sits
C8 6,800 µF 25 V Main filter, after the bridge rectifier D1-D4 and before the regulators
C7 33 µF 16 V Output of A6 (HA17805P), the Vc +5 V rail for logic and motors
C6 10 µF 16 V Output of A5 (HA17805P), the Vp +5 V rail for the pen solenoid
C13 1 µF 35 V Reset pin of A2, the printer controller
C14 4.7 µF or 47 µF (the hosted scan is not clear) 35 V Reset pin of A1, the serial/parallel controller

The board also carries a 1 µF 100 V film capacitor (C15) across the AC input and 0.1 µF 50 V ceramic capacitors (C3, C4, C5) beside the regulators; these are not electrolytics.[1] Check the value printed on C14 itself before ordering.

Signs of failure

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  • No power LED. Atari's flowchart checks for 8-13 V DC on pin 1 of A6 and, if it is present with no 5 V out, blames A6 or a shorted C3 or C7.[1]
  • Bulging, leakage or a vented top on C8, the largest capacitor; see Capacitor Failure Symptoms.

C13 and C14 hold the two microcontrollers in reset for a moment at switch-on.[1]

Procedure

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  1. Unplug the adaptor; Atari warns against any disassembly with AC power connected.[1]
  2. Open the printer and lift out the printer module as described in the Atari 1020 Maintenance Guide.
  3. Remove the board's four screws and lift it out.[2]
  4. Replace the capacitors one at a time, observing polarity.

Checks after recapping

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Voltages to check (FD100288)
Point Expected
Anode of D4 9 V AC from the adaptor
Pin 1 of A6 8-13 V DC
Pin 3 of A6 (Vc) +5 V DC ±5 %
Output of A5 (Vp) +5 V DC ±5 %

The figures are from the no power and pen-down flowcharts and the power supply description.[1] Then switch on and confirm the four-square test pattern; see the Atari 1020 Troubleshooting page.

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References

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  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Atari, Inc., 1020 Color Printer Field Service Manual, FD100288 Rev. 01, August 1983: power supply and noise limit capacitors (pp. 1-8 and 1-9); power-on reset (p. 1-12); no power flowchart (p. 4-4); schematic, figure 2-2 (p. 2-5). Hosted here as File:Atari 1020 Color Printer Field Service Manual FD100288 Rev 01.pdf.
  2. ↑ RetroNerd, "Atari 1020 Colour Printer Plotter Repair", 7 January 2024. retronerd.co.uk. Community repair write-up.


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