Atari STE Capacitor Replacement Guide

This guide provides complete capacitor lists and replacement procedures for the Atari 520STE and Atari 1040STE computers. Both models use the same motherboard — either the CA401177 or CA4003290 revision — so the capacitor list is identical for the 520STE and 1040STE.

For the earlier Atari ST/STF/STFM range (520ST, 1040ST), see Atari ST Capacitor Replacement Guide.

When to Recap

The STE was produced from 1989 to approximately 1993, making these machines 33–37 years old. While the electrolytic capacitors on the STE motherboard have generally proven reliable, replacement is recommended as preventive maintenance. The PSU should be recapped as a first priority.

Symptoms of failing capacitors include:

• Unstable video or ghosting/wavy lines
• Audio distortion on both PSG and DMA channels
• Random crashes or freezes
• Intermittent boot failures
• Screen dimming during floppy access
• DMA sound playback issues

Motherboard Capacitor List

The following list covers both known STE motherboard revisions: CA401177 and CA4003290. Some minor value differences between early and late boards are noted.

Ref. Designator	Capacitance	Voltage	Type	Circuit Area / Notes
C100	10 µF	35V	Electrolytic	Power filtering
C102	22 µF	16V	Electrolytic	May be 10 µF / 35V on some early boards
C103	4700 µF	16V	Electrolytic	Main +5V bulk filter — large radial cap
C107	100 µF	16V	Electrolytic	Power filtering
C110	100 µF	16V	Electrolytic	Power filtering
C202	4.7 µF	35V	Non-polarised	Audio path
C204	4.7 µF	35V	Non-polarised	Audio path
C205	4.7 µF	35V	Non-polarised	Audio path
C215	4.7 µF	35V	Non-polarised	Audio path
C216	470 µF	35V	Electrolytic	Audio output — main coupling cap
C415	470 µF	16V	Electrolytic	Power filtering
C416	47 µF	16V	Electrolytic
C417	100 µF	16V	Electrolytic
C423	100 µF	16V	Electrolytic
C433	1 µF	50V	Electrolytic
C508	47 µF	16V	Electrolytic
C520	47 µF	16V	Electrolytic
C525	47 µF	16V	Electrolytic
C529	47 µF	16V	Electrolytic
C535	47 µF	16V	Electrolytic
C537	47 µF	16V	Electrolytic
C541	47 µF	16V	Electrolytic
C542	10 µF	35V	Electrolytic
C543	47 µF	16V	Electrolytic
C544	47 µF	16V	Electrolytic
C546	47 µF	16V	Electrolytic
C547	47 µF	16V	Electrolytic
C558	100 µF	16V	Electrolytic
C561	100 µF	16V	Electrolytic
C564	100 µF	16V	Electrolytic
C566	47 µF	16V	Electrolytic
C567	47 µF	16V	Electrolytic
C600	100 µF	16V	Electrolytic

Total: 32 electrolytic capacitors on the STE motherboard.

Non-Polarised Capacitors

Four positions (C202, C204, C205, C215) require non-polarised (bipolar) electrolytic capacitors. These are in the audio output path and must not be replaced with standard polarised electrolytics. Console5 cap kits include radial bipolar electrolytics for these positions. Alternatively, film capacitors of the appropriate value can be used.

Key Capacitors

• C103 (4700 µF, 16V): This is the main +5V bulk filter capacitor and is physically the largest cap on the board. Its failure is the most likely single cause of instability. Replace with a quality low-ESR part.
• C216 (470 µF, 35V): Main audio output coupling capacitor. Failure causes distorted or absent audio output.
• C202, C204, C205, C215 (4.7 µF, 35V NP): Audio path non-polarised caps. Deterioration causes audio distortion and channel imbalance.

PSU Capacitor Lists

The STE uses the same PSU types as the 1040ST. Refer to ST Capacitor Replacement Guide — PSU Capacitor Lists for complete lists of:

• Mitsumi SR98 / SR118 / 68-4231A (220–240V)
• ASTEC ASP34 / ASPF34 (220–240V)
• DVE DSP-508A / DSP-508AA (220–240V)
• Mitsumi SR97 / 68-4242A (110–120V)

The PSU models are physically interchangeable between the 1040ST and STE.

Internal Floppy Drive Capacitors

The STE's internal floppy drive uses the same type of drive mechanism as the 1040ST. See ST Capacitor Replacement Guide — Floppy Drive Caps for the capacitor list (TDK D357 / T41V).

Replacement Procedure

Tools Required

Same as for the ST family — see ST Capacitor Replacement Guide — Tools.

Motherboard Recap Procedure

1. Open the case and disconnect the PSU and floppy drive from the motherboard (see STE General Maintenance — Opening the Case).
2. Remove the SIMMs before starting soldering work to protect them from heat and flux contamination.
3. Photograph the board before starting, noting all capacitor polarities.
4. Work through each capacitor position, desoldering the old cap, cleaning the pads, and soldering the replacement.
5. The STE motherboard uses a mix of axial and radial capacitor footprints. Most of the 47 µF caps in the C500–C600 range are axial. Modern radial replacements can be used by bending leads or mounting upright.
6. Take extra care around the GST MCU (U400) and GST Shifter — these are surface-mount chips and can be damaged by excessive heat from nearby soldering. Use a fine tip and work quickly near these ICs.
7. After completing all replacements, clean the board thoroughly with IPA and a brush to remove flux residue.
8. Reinstall SIMMs and reconnect all cables.

PSU Recap Procedure

Same as for the 1040ST — see ST Capacitor Replacement Guide — PSU Recap Procedure. All safety warnings about mains voltage apply.

Post-Recap Voltage Checks

Test Point	Expected Value	Tolerance	Notes
+5V at motherboard power header	5.00V	±0.25V	Measure with machine powered on and under normal load.
+12V at motherboard power header	12.0V	±1.0V	Needed for floppy and RS-232.
+5V ripple (oscilloscope)	<200 mV pk-pk	—	Indicates healthy PSU caps. >500 mV indicates a remaining problem.
+5V at CPU VCC pin	4.90V – 5.10V	—	Check for excessive voltage drop from header to CPU.
DMA sound output	Present on audio out pin	—	Play a DMA sound sample after recap to verify audio path caps are working.

Board Revision Identification

To identify your STE motherboard revision:

• CA401177: Earlier production. May have surface-mounted MC68000 CPU. The board number is printed on the PCB near the edge.
• CA4003290: Later production. More commonly found. MC68000 is typically DIP-64 (socketed). Board number printed on PCB.

Both revisions use the same capacitor list. Minor component layout differences may exist but the electrolytic capacitor positions, values, and designators are the same.

Sourcing Capacitor Kits

Pre-assembled STE motherboard cap kits are available from:

• Console5 (console5.com) — Kit specifically for CA401177 / CA4003290 STE boards, including non-polarised 4.7 µF parts
• exxos (exxosforum.co.uk/atari/store2) — PSU recap kits

When sourcing individual caps, use reputable suppliers (Farnell, Mouser, Digikey, RS Components). The four non-polarised 4.7 µF parts can be difficult to source — Nichicon UES or Panasonic NHG series bipolar electrolytics are suitable.

Related Pages

• Atari 1040STE
• Atari STE General Maintenance
• Atari STE Troubleshooting Guide
• Atari ST Capacitor Replacement Guide