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Atari Jaguar Capacitor Replacement Guide

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Jaguar main board 700026-001. C150 (2200 µF) and the regulator U38 are at the top right; the video and audio electrolytics are along the bottom edge

The Atari Jaguar main board has twenty aluminium electrolytic capacitors on Atari's schematic, SCH. Jaguar Console, document 500162 Rev. 5.3 of 21 September 1993.[1] All the others are ceramic decoupling and filter parts. The schematic gives a value for every electrolytic but prints a voltage rating for only four of them, so read the rating off the old part, or off the board, before ordering.

The Jaguar CD add-on has its own board and its own list; see the Atari Jaguar CD Capacitor Replacement Guide.

Capacitor list

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Jaguar main board electrolytics (Atari schematic 500162 Rev. 5.3)
Ref Value on the schematic Where it sits on the schematic
C142 10 µF 25 V Power input (VIN), after the choke CH1
C134 330 µF Input to the MC34163 switching regulator (U38)
C150 2200 µF, "Low Z" +5 V output of U38, after L29 (120 µH) and D4
C174 4.7 µF, "Low Z" +5 V (VCC) rail, beside C175
C43 10 µF 25 V 9 V input to the audio regulator REG1, after the power switch SW1B
C24 2.2 µF Output of REG1 (LM78L05ACM), AUDIO_VCC at TP6
C39 22 µF 10 V AUDIO_VCC decoupling
C22 10 µF Supply of the TDA1545 audio DAC (U5)
C21 1 µF Reference (AVREF) for the TDA1308T audio amplifier (U4)
C10 10 µF Right audio output coupling, after U4A
C34 10 µF Left audio output coupling, after U4B
C8 100 µF VIDEO_VCC, after the 100 µH choke L34
C7 100 µF VIDEO_VCC, at the MC13077 video encoder (U3)
C14 1 µF Red input coupling to U3
C17 1 µF Green input coupling to U3
C18 1 µF Blue input coupling to U3
C45 47 µF Composite video coupling to the RF modulator
C11 10 µF 6 V RF modulator supply
C42 10 µF Reset circuit (RESETIL), with R77 and D2
C93 10… (the rest of the value is illegible in the scan) Supply to the ADC0844 joystick converter, through R110 (10 Ω)

Values, ratings where printed, and positions are read from the schematic.[1] The "Low Z" marking on C150 and C174 means Atari specified low-impedance parts for the regulator output; fit low-ESR replacements there.

C142 and C134 sit on the raw adaptor input, which the label of the Atari adaptor gives as 9 V DC.[2] Do not fit anything rated below the 25 V Atari printed for C142 in either position.

Board versions

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Wikipedia records two Jaguar versions, distinguished by the first letter of the serial number: "K" units made by IBM and "M" units made by JVC. Early "K" units have the analogue-controller converter chip; later "K" and "M" units do not.[3] On those boards the ADC0844 and its supply capacitor C93 may be absent. Evan-Amos's photograph shows a board labelled 700026-001.[4]

Procedure

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See Recommended Tools for equipment and Capacitor Failure Symptoms for what a failed part looks like.

  1. Unplug the adaptor and remove the cartridge.
  2. Open the case and remove the steel RF shield that covers the main board.[5]
  3. Work on one capacitor at a time. Note the polarity marking on the board before removing each part.
  4. Pay most attention to the power section at the top right of the board (C150, C134 and U38) and the audio section at the bottom right; the photograph of a 700026-001 board shows the electrolytics there.[4]
  5. Clean off the flux and check the joints before refitting the shield.

After the recap

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  • With a cartridge in and the power switch on, the power LED should light. Atari's schematic feeds the LED D3 from the +5 V rail (VCC) through R126 (150 Ω), so the LED is also a quick check that the switching regulator is running.[1]
  • Measure AUDIO_VCC at TP6: it is the output of the LM78L05 regulator REG1 and should be 5 V.[1]
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References

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  1. ↑ 1.0 1.1 1.2 1.3 Atari Corporation, SCH. Jaguar Console, document 500162 Rev. 5.3, 21 September 1993: power section (PSUCON, CH1, SD1, SW1, U38, REG1), video section (U7, Q2-Q4, U3, MOD1), audio section (U5, U4), reset circuit and ADC0844. Hosted here as File:Atari Jaguar Console Schematic 500162 Rev 5.3.pdf.
  2. ↑ Evan-Amos, photograph of the Atari Jaguar/Jaguar CD adaptor model PP-912 and its label (Atari P/N 500273, output DC 9 V 1.2 A), 20 June 2014. Hosted here as File:Atari Jaguar power supply (PP-912).jpg.
  3. ↑ Wikipedia, "Atari Jaguar", revision of 10 September 2026, section "Technical specifications".
  4. ↑ 4.0 4.1 Evan-Amos, photograph of an Atari Jaguar main board, assembly 700026 (label 700026-001), 21 June 2014. Hosted here as File:Atari Jaguar motherboard (700026-001).jpg.
  5. ↑ Evan-Amos, photograph of a Jaguar with the top case removed and the RF shield in place, 19 June 2014. Hosted here as File:Atari Jaguar with RF shield in place.jpg.


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