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Rebuild from Atari 400/800 Field Service Manual (hosted): the old C56-C65 mainboard table and C1-C4 PSU table were fabricated - the 800 motherboard starts at C101 and has exactly two electrolytics (C179, C199). Real PSU list is C201/202/204/205/207/208/210/211. Removed the non-existent '+9V rail'; added real rails, regulators and clock table; cited throughout
 
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[[File:Atari 800 (photo).jpg|thumb|right|300px|Atari 800]]
The '''[[Atari 800]]''' is a five-board machine: motherboard, power supply PCB, a plug-in CPU card, a plug-in ROM personality module and one to three plug-in RAM modules. '''Ten aluminium electrolytic capacitors exist in the whole computer''', eight of them on the power supply PCB. Nothing on the CPU card, the ROM module or the RAM modules is an electrolytic, and no amount of age will change that.


<templatestyles src="Template:StyledTable/styles.css" />
The values below come from Atari's own parts list in the ''ATARI Home Computer Field Service Manual 400/800''.<ref name="fsm">Atari, Inc., ''ATARI Home Computer Field Service Manual 400/800'', June 1982, Section 9, "ATARI 800 Computer Console Parts List", pages 9-7 to 9-13. Hosted on this wiki: [[:File:Atari 400 800 Field Service Manual June 82.pdf]]. Source of every capacitor value, voltage rating, reference designator and Atari part number on this page.</ref>


Recapping your '''Atari 800''' is essential for reliable operation, stable video, and protection of irreplaceable custom chips. After four decades, the original aluminium electrolytic capacitors are prone to drying out, leaking, or failing open—leading to random crashes, distorted audio, power instability, or even permanent board damage. Proactive replacement of these components restores performance and extends the life of your classic Atari.
== How the 800 is numbered ==


== 🔍 Visual Inspection & Failure Signs ==
Atari allocated a block of reference designators to each board. Use it as a sanity check on any parts list you are handed:<ref name="fsm" />


Before recapping, carefully examine all electrolytic capacitors for:
{| class="wikitable styled-table" style="width:85%;"
|+ Atari 800 reference designator blocks
! Board !! Atari assembly number !! Designators
|-
| Motherboard || — || C101–C200, R101–R185, A101–A103, Z101–Z106
|-
| Power supply PCB || CA014171 || C201–C216, R201–R204, A201–A203, S201–S207, J201–J206
|-
| CPU card || CA017173 || C301–C307, R302–R313, A301–A303, Z301–Z304
|-
| ROM personality module || CA014090-01 / CA014803 || C401–C411, R401–R404, A401–A403, Z401–Z403
|-
| RAM module || CA014802 (16K) || C501–C523, Z501–Z512
|}
 
A list quoting "C56–C65 on the 800 mainboard" is not describing this computer — the motherboard's capacitors start at C101.


* '''Bulging or domed tops''' – Indicates internal gas build-up and imminent failure.
== Visual inspection and failure signs ==
* '''Leaking electrolyte''' – Brown, black, or green residue at the base or on the PCB.
* '''Corrosion or PCB staining''' – Discolouration or green/white crust around capacitor leads.
* '''Unusual odours''' – A fishy or acrid smell often signals capacitor leakage.
* '''System symptoms''' – Random lockups, video flicker, audio hum, or power-on issues.


If '''any''' capacitor shows signs of failure, replace '''all''' electrolytics on the mainboard and power supply for best results.
* '''Bulging or domed tops.'''
* '''Leaking electrolyte''' — brown, black or green residue at the base or on the board.
* '''Corrosion or board staining''' around the leads.
* '''Random lock-ups, video flicker, audio hum or power-on failure.'''


== 📋 Atari 800 Capacitor List ==
See [[Capacitor Failure Symptoms]], and [[Battery Explosion, Capacitor or Corrosion Damage]] if electrolyte has already spread.


The Atari 800 uses only through-hole electrolytic capacitors on its mainboard and power supply board. SMD electrolytics are not present. Always double-check values and polarity before replacement, as minor revisions exist.
== Capacitor list ==


=== 🖥️ Mainboard Electrolytic Capacitors ===
=== Power supply PCB (CA014171) ===


<templatestyles src="Template:StyledTable/styles.css" />
{| class="wikitable styled-table" style="width:90%; text-align:center;"
{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+ Atari 800 power supply PCB electrolytic capacitors
|+'''Atari 800 Mainboard Electrolytic Capacitors'''
! Designator !! Value !! Rating !! Package !! Atari part number
! Ref. Designator !! Capacitance !! Voltage !! Function / Notes
|-
|-
| C56 || 2200 µF || 16 V || Main +5 V filter (bulk smoothing)
| C201 || 470 µF || 16 V || Axial || C014370
|-
|-
| C57 || 470 µF || 16 V || +12 V rail filter (regulator output)
| C202 || 470 µF || 16 V || Axial || C014370
|-
|-
| C58 || 47 µF || 16 V || +5 V local decoupling (CPU/ANTIC)
| C204 || 2200 µF || 16 V || Axial || C014373
|-
|-
| C59 || 10 µF || 16 V || Reset circuit timing
| C205 || 2200 µF || 16 V || Axial || C014373
|-
|-
| C60 || 10 µF || 16 V || Audio path (DC-blocking)
| C207 || 4700 µF || 16 V || Radial || C014374-01 or C014374-02
|-
|-
| C61 || 4.7 µF || 25 V || Video output coupling
| C208 || 4700 µF || 16 V || Radial || C014374-01 or C014374-02
|-
|-
| C62 || 1 µF || 50 V || Colour circuit coupling
| C210 || 10 µF || 16 V || Axial || C014371
|-
|-
| C63 || 10 µF || 16 V || Power-on reset filter
| C211 || 10 µF || 16 V || Axial || C014371
|}
 
'''Board revision note.''' Atari's parts list rates C207 and C208 at 16 V. The Console5 Tech Wiki, which lists the 800 supply board as "Power Supply, REV B", gives 25 V for those two positions and agrees with Atari on everything else.<ref name="c5">[https://wiki.console5.com/wiki/Atari_800 "Atari 800"], Console5 Tech Wiki, retrieved September 2026. Secondary source. Its list matches Atari's parts list except that it rates C207/C208 at 25 V and labels the board "Power Supply, REV B".</ref> Read what is printed on the parts actually in your machine. Either way a 25 V part is a safe replacement in a 16 V position; the reverse is not true.
 
The non-electrolytics on this board should be left alone unless they test faulty: C203 and C206 are 0.22 µF 100 V polyester film, C215 is 0.47 µF 100 V mylar, C209 is 0.1 µF ceramic, C212 and C216 are 0.001 µF ceramic and C214 is 10 pF.<ref name="fsm" />
 
=== Motherboard ===
 
{| class="wikitable styled-table" style="width:80%; text-align:center;"
|+ Atari 800 motherboard electrolytic capacitors
! Designator !! Value !! Rating !! Package !! Atari part number
|-
|-
| C64 || 100 µF || 16 V || +5 V local decoupling (GTIA/POKEY)
| C179 || 10 µF || 16 V || Radial || C014392
|-
|-
| C65 || 47 µF || 16 V || +12 V local decoupling
| C199 || 10 µF || 16 V || Axial || C014371
|}
|}


''Some late-production boards may have minor value changes; always match what is fitted.''
These two are the only electrolytics on the motherboard. Note that they are different physical parts — C179 is radial, C199 axial — although both are 10 µF 16 V.<ref name="fsm" /> C179 is one of the components Atari's own symptom checklist names for "tones missing during sound or games".<ref name="fsmsym">Atari, Inc., ''ATARI Home Computer Field Service Manual 400/800'', June 1982, Section 6, "Symptom Checklist", pages 6-1 and 6-2.</ref>
 
=== CPU card, ROM module and RAM modules ===
 
'''None of the plug-in boards contains an electrolytic capacitor.'''<ref name="fsm" /> C301–C307, C401–C411 and C501–C523 are all ceramic axial types at 0.001 µF, 0.01 µF, 0.1 µF or small NP0 values. Leave them alone.


=== 🔌 Internal Power Supply Board Capacitors ===
== What the rails actually are ==


The Atari 800’s internal power supply (not the external “brick”) contains additional electrolytics:
Atari states that the power supply PCB "receives 9 VAC from an external power adaptor (transformer) and provides +5 Vdc, +12 Vdc, and −5 Vdc for the Console system", and breaks the rails down as follows:<ref name="fsmps">Atari, Inc., ''ATARI Home Computer Field Service Manual 400/800'', June 1982, page 1-6, "Power Supply". Source of the 9 V AC input figure and the rail breakdown.</ref>


<templatestyles src="Template:StyledTable/styles.css" />
{| class="wikitable styled-table" style="width:80%;"
{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+ Atari 800 supply rails
|+'''Atari 800 Power Supply Board Electrolytic Capacitors'''
! Rail !! Purpose
! Ref. Designator !! Capacitance !! Voltage !! Function / Notes
|-
|-
| C1 || 4700 µF || 25 V || Main DC reservoir (after rectifier)
| +5 V A || Supply voltage for the logic PCBs
|-
|-
| C2 || 220 µF || 25 V || +12 V regulator input filter
| +5 V B || Specially filtered supply for the video circuitry
|-
|-
| C3 || 220 µF || 16 V || +5 V regulator input filter
| +12 V || Supply for the dynamic RAM chips, and SIO pin 12
|-
|-
| C4 || 10 µF || 25 V || Regulator output decoupling
| −5 V || Supply for the dynamic RAM chips
|}
|}


''If your 800 has a third-party or repaired PSU, values may differ—replace like-for-like.''
There is no "+9 V rail". The 9 V is AC, it is what comes in from the adaptor (Atari part C014319), and it is rectified on the supply board by CR206–CR209 (MR501). The regulators are '''A202 (5 V, C014348)''' and '''A201 (12 V, C014349)''' on the heatsink assembly CA014708.<ref name="fsm" />
 
== Recapping procedure ==


== 🛠️ Recapping Procedure ==
{{Warning|The power supply PCB carries the incoming 9 V AC as far as the rectifiers, and the ON/OFF switch S202 opens that AC input rather than a DC rail. Unplug the adaptor at the wall before working on the board. C207 and C208 are 4700 µF and will hold a charge after power-off — discharge them through a resistor before handling the board.}}


# '''Unplug all power''' and peripherals. Remove the top cover and keyboard.
# Unplug the adaptor and all peripherals. Remove the top cover and lift out the ROM and RAM modules.
# '''Remove the RF shield''' (desolder or carefully unbend tabs).
# Remove the metal shielding to reach the boards. On the 800 the module bay is enclosed by a primary shield casting (C012763) and a lower shield (C012764); note the insulator (C015352) when you take it apart.<ref name="fsm" />
# '''Label and disconnect''' all internal cables (keyboard, power, video).
# Label every connector before disconnecting: J204 (13-pin SIO), J205 (DIN monitor socket), J206 (power jack), J201 (22-pin socket) and J202 (4-pin).
# '''Desolder each capacitor''' using braid or a pump. Atari used robust, high-temperature solder; set iron to '''370–380 °C'''.
# Desolder each capacitor with braid or a pump; Atari's assembly solder is high-melting, so use a hot iron and work quickly rather than dwelling on the pad.
# '''Clean pads''' with isopropyl alcohol and inspect for lifted traces or corrosion.
# Clean the pads with isopropyl alcohol and inspect for lifted traces.
# '''Install new capacitors''', matching '''polarity''' and '''lead spacing''' (most are 5 mm or 7.5 mm).
# Fit the new capacitors observing '''polarity''' and lead spacing. A higher voltage rating is always acceptable; a lower one never is.
# '''Trim leads and solder''', ensuring shiny, solid joints.
# Reassemble and verify before refitting the modules.
# '''Reassemble''' and double-check all connectors before applying power.


== 🧰 Recommended Tools & Parts ==
== Recommended parts ==


* Temperature-controlled soldering iron (2 mm chisel tip)
* 105 °C radial aluminium electrolytics from a reputable manufacturer. C207/C208 are radial in the original design; C201, C202, C204, C205, C210, C211 and C199 are axial.
* Desoldering braid and/or spring pump
* Keep replacement can heights low enough to clear the shield castings.
* Leaded 63/37 or quality lead-free solder
* See [[Recommended Tools]].
* '''105 °C, low-ESR''' radial electrolytic capacitors (Nichicon PW/PS, Panasonic FR/FC, Rubycon ZL/ZLH)
* Isopropyl alcohol (IPA) and antistatic brush
* Kapton tape (to insulate capacitors near shielding)
* Multimeter (for continuity and voltage checks)
* ESD wrist strap (recommended)


== ⚙️ Post-Recap Voltage & Ripple Check ==
== Verifying the result ==


After reassembly, verify all voltage rails under load (computer powered, BASIC READY):
Atari does not publish a tolerance band for the 800's internal rails, so treat the regulator types as the specification and measure at the regulator tabs or at the large filter capacitors. The genuinely specified figures are the clock frequencies:<ref name="fsmclock">Atari, Inc., ''ATARI Home Computer Field Service Manual 400/800'', June 1982, Table 5-1, "Clock Circuit", page 5-36.</ref>


{| class="wikitable styled-table" style="width:80%; text-align:center;"
{| class="wikitable styled-table" style="width:80%; text-align:center;"
|+'''Atari 800 Voltage Rails (measured at mainboard test points)'''
|+ Clock check points (Atari Table 5-1)
! Test Point !! Expected Voltage !! Max Ripple (p-p)
! Point !! Board !! Frequency (MHz)
|-
|-
| +5 V (CPU, ANTIC, GTIA) || 4.90 – 5.15 V || < 50 mV
| Pin 21 of J101 || CPU card || 1.789
|-
|-
| +12 V (POKEY, audio, video) || 11.5 – 12.5 V || < 100 mV
| Pin 9 of Z302 || CPU card || 1.789
|-
|-
| +9 V (unregulated, after rectifier) || 8.5 – 10.5 V || sine-like
| Pin 35 of A302 (ANTIC) || CPU card || 3.579
|-
| Pin 29 of A301 (GTIA) || CPU card || 3.579
|-
| Collector of Q102 || Motherboard || 3.579
|-
| Pin 7 of A101 (POKEY) || Motherboard || 1.789
|-
| Pin 25 of A102 (PIA) || Motherboard || 1.789
|}
|}


''Excessive ripple or voltages out of range may indicate a failing external PSU or regulator fault.''
If the rails and the clock are both right and the machine still fails, work through [[Atari 800 Troubleshooting Guide]].


== 💡 Extra Tips ==
== Related pages ==
* [[Atari 800]]
* [[Atari 800 General Maintenance]]
* [[Atari 800 Troubleshooting Guide]]
* [[Atari 400 Capacitor Replacement Guide]]
* [[Capacitor Failure Symptoms]]
* [[Recommended Tools]]


* '''Test the external PSU first''' – Overvoltage or AC ripple can destroy new capacitors and custom chips.
== References ==
* '''Observe polarity carefully''' – Atari silkscreen markings are not always clear; double-check before soldering.
<references />
* '''Use quality capacitors''' – Cheap generics often fail early; use reputable brands.
* '''Clean any leaked electrolyte''' thoroughly – It is corrosive and can damage traces.
* '''Inspect for previous repairs''' – If you find bodged or missing parts, consult the schematic before proceeding.
* '''Retain original lead dress''' – Keep replacement capacitors close to the board to avoid RF shield contact.
* '''Re-seat socketed chips''' after recapping – Power cycling can unseat them.


== 🔗 Related Pages ==
* [[Atari 800 Troubleshooting Guide]]
* [[Atari 400/800 Power Supply Repair]]
* [[Atari 8-bit Video Output Upgrades]]
[[Category:Atari Systems]]
[[Category:Atari Systems]]
[[Category:Capacitor Replacement Guides]]
[[Category:Capacitor Replacement Guides]]
{{Navbox-AtariVintageComputers|state=collapsed}}

Latest revision as of 22:21, 22 September 2026

Atari 800

The Atari 800 is a five-board machine: motherboard, power supply PCB, a plug-in CPU card, a plug-in ROM personality module and one to three plug-in RAM modules. Ten aluminium electrolytic capacitors exist in the whole computer, eight of them on the power supply PCB. Nothing on the CPU card, the ROM module or the RAM modules is an electrolytic, and no amount of age will change that.

The values below come from Atari's own parts list in the ATARI Home Computer Field Service Manual 400/800.[1]

How the 800 is numbered

[edit | edit source]

Atari allocated a block of reference designators to each board. Use it as a sanity check on any parts list you are handed:[1]

Atari 800 reference designator blocks
Board Atari assembly number Designators
Motherboard — C101–C200, R101–R185, A101–A103, Z101–Z106
Power supply PCB CA014171 C201–C216, R201–R204, A201–A203, S201–S207, J201–J206
CPU card CA017173 C301–C307, R302–R313, A301–A303, Z301–Z304
ROM personality module CA014090-01 / CA014803 C401–C411, R401–R404, A401–A403, Z401–Z403
RAM module CA014802 (16K) C501–C523, Z501–Z512

A list quoting "C56–C65 on the 800 mainboard" is not describing this computer — the motherboard's capacitors start at C101.

Visual inspection and failure signs

[edit | edit source]
  • Bulging or domed tops.
  • Leaking electrolyte — brown, black or green residue at the base or on the board.
  • Corrosion or board staining around the leads.
  • Random lock-ups, video flicker, audio hum or power-on failure.

See Capacitor Failure Symptoms, and Battery Explosion, Capacitor or Corrosion Damage if electrolyte has already spread.

Capacitor list

[edit | edit source]

Power supply PCB (CA014171)

[edit | edit source]
Atari 800 power supply PCB electrolytic capacitors
Designator Value Rating Package Atari part number
C201 470 µF 16 V Axial C014370
C202 470 µF 16 V Axial C014370
C204 2200 µF 16 V Axial C014373
C205 2200 µF 16 V Axial C014373
C207 4700 µF 16 V Radial C014374-01 or C014374-02
C208 4700 µF 16 V Radial C014374-01 or C014374-02
C210 10 µF 16 V Axial C014371
C211 10 µF 16 V Axial C014371

Board revision note. Atari's parts list rates C207 and C208 at 16 V. The Console5 Tech Wiki, which lists the 800 supply board as "Power Supply, REV B", gives 25 V for those two positions and agrees with Atari on everything else.[2] Read what is printed on the parts actually in your machine. Either way a 25 V part is a safe replacement in a 16 V position; the reverse is not true.

The non-electrolytics on this board should be left alone unless they test faulty: C203 and C206 are 0.22 µF 100 V polyester film, C215 is 0.47 µF 100 V mylar, C209 is 0.1 µF ceramic, C212 and C216 are 0.001 µF ceramic and C214 is 10 pF.[1]

Motherboard

[edit | edit source]
Atari 800 motherboard electrolytic capacitors
Designator Value Rating Package Atari part number
C179 10 µF 16 V Radial C014392
C199 10 µF 16 V Axial C014371

These two are the only electrolytics on the motherboard. Note that they are different physical parts — C179 is radial, C199 axial — although both are 10 µF 16 V.[1] C179 is one of the components Atari's own symptom checklist names for "tones missing during sound or games".[3]

CPU card, ROM module and RAM modules

[edit | edit source]

None of the plug-in boards contains an electrolytic capacitor.[1] C301–C307, C401–C411 and C501–C523 are all ceramic axial types at 0.001 µF, 0.01 µF, 0.1 µF or small NP0 values. Leave them alone.

What the rails actually are

[edit | edit source]

Atari states that the power supply PCB "receives 9 VAC from an external power adaptor (transformer) and provides +5 Vdc, +12 Vdc, and −5 Vdc for the Console system", and breaks the rails down as follows:[4]

Atari 800 supply rails
Rail Purpose
+5 V A Supply voltage for the logic PCBs
+5 V B Specially filtered supply for the video circuitry
+12 V Supply for the dynamic RAM chips, and SIO pin 12
−5 V Supply for the dynamic RAM chips

There is no "+9 V rail". The 9 V is AC, it is what comes in from the adaptor (Atari part C014319), and it is rectified on the supply board by CR206–CR209 (MR501). The regulators are A202 (5 V, C014348) and A201 (12 V, C014349) on the heatsink assembly CA014708.[1]

Recapping procedure

[edit | edit source]
  1. Unplug the adaptor and all peripherals. Remove the top cover and lift out the ROM and RAM modules.
  2. Remove the metal shielding to reach the boards. On the 800 the module bay is enclosed by a primary shield casting (C012763) and a lower shield (C012764); note the insulator (C015352) when you take it apart.[1]
  3. Label every connector before disconnecting: J204 (13-pin SIO), J205 (DIN monitor socket), J206 (power jack), J201 (22-pin socket) and J202 (4-pin).
  4. Desolder each capacitor with braid or a pump; Atari's assembly solder is high-melting, so use a hot iron and work quickly rather than dwelling on the pad.
  5. Clean the pads with isopropyl alcohol and inspect for lifted traces.
  6. Fit the new capacitors observing polarity and lead spacing. A higher voltage rating is always acceptable; a lower one never is.
  7. Reassemble and verify before refitting the modules.
[edit | edit source]
  • 105 °C radial aluminium electrolytics from a reputable manufacturer. C207/C208 are radial in the original design; C201, C202, C204, C205, C210, C211 and C199 are axial.
  • Keep replacement can heights low enough to clear the shield castings.
  • See Recommended Tools.

Verifying the result

[edit | edit source]

Atari does not publish a tolerance band for the 800's internal rails, so treat the regulator types as the specification and measure at the regulator tabs or at the large filter capacitors. The genuinely specified figures are the clock frequencies:[5]

Clock check points (Atari Table 5-1)
Point Board Frequency (MHz)
Pin 21 of J101 CPU card 1.789
Pin 9 of Z302 CPU card 1.789
Pin 35 of A302 (ANTIC) CPU card 3.579
Pin 29 of A301 (GTIA) CPU card 3.579
Collector of Q102 Motherboard 3.579
Pin 7 of A101 (POKEY) Motherboard 1.789
Pin 25 of A102 (PIA) Motherboard 1.789

If the rails and the clock are both right and the machine still fails, work through Atari 800 Troubleshooting Guide.

[edit | edit source]

References

[edit | edit source]
  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Atari, Inc., ATARI Home Computer Field Service Manual 400/800, June 1982, Section 9, "ATARI 800 Computer Console Parts List", pages 9-7 to 9-13. Hosted on this wiki: File:Atari 400 800 Field Service Manual June 82.pdf. Source of every capacitor value, voltage rating, reference designator and Atari part number on this page.
  2. ↑ "Atari 800", Console5 Tech Wiki, retrieved September 2026. Secondary source. Its list matches Atari's parts list except that it rates C207/C208 at 25 V and labels the board "Power Supply, REV B".
  3. ↑ Atari, Inc., ATARI Home Computer Field Service Manual 400/800, June 1982, Section 6, "Symptom Checklist", pages 6-1 and 6-2.
  4. ↑ Atari, Inc., ATARI Home Computer Field Service Manual 400/800, June 1982, page 1-6, "Power Supply". Source of the 9 V AC input figure and the rail breakdown.
  5. ↑ Atari, Inc., ATARI Home Computer Field Service Manual 400/800, June 1982, Table 5-1, "Clock Circuit", page 5-36.



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