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[[File:Apple_mac_quadra_800.jpg|thumb|Macintosh Quadra 800]]
Replacing electrolytic capacitors (recapping) in your '''Macintosh Quadra 800''' can restore proper operation and prevent future failures. Unlike earlier compact Macintosh models that used surface-mount electrolytic capacitors prone to leakage, the Quadra 800 uses through-hole capacitors on the logic board, which are generally more reliable but can still fail with age.
This guide covers capacitor diagnosis and replacement on the '''[[Macintosh Quadra 800]]''' and the Workgroup Server 80, which share one logic board, one enclosure and one power supply.<ref name="ss800">Apple Computer, ''Macintosh Quadra 800/WS 80 Service Source'' — hosted on this wiki as [[:File:Quadra_800.ws_80.pdf]]. Chapters used here: Specifications (Processor, Electrical), Troubleshooting (Symptom Charts) and Additional Procedures (Battery Verification, Battery Replacement).</ref>


== When to Recap ==
On this machine the work is in the power supply. The logic board is a different design from the leaking surface-mount boards of the same period.


Consider recapping if you observe:
<templatestyles src="Template:StyledTable/styles.css" />
 
== Safety ==
 
The supply is a mains-rectified switcher. Its primary side sits at mains potential and the two 200 V bulk capacitors hold a charge that can kill after the machine is unplugged. Recapping it is a reasonable job, but treat it as live-mains work:
 
# Switch off and unplug the mains lead.
# Discharge each bulk capacitor through a 1 kΩ / 5 W resistor across its terminals and confirm with a meter that it reads near zero.
# Work one-handed where practical, and do not probe a powered primary side without an isolation transformer.
 
This supply comes apart into five stacked boards, which means components on the primary side end up exposed and easy to reach across. One member who reassembled it with a joint left unsoldered had the mains-side safety capacitors detonate when he plugged it in — nothing caught fire, but it was loud and it could have been much worse.<ref name="mla220db">68kMLA forum thread [https://68kmla.org/bb/threads/in-search-of-list-of-capcaitors-for-delta-smp-220db-psu-apple-p-n-614-0012.37852/ "In search of list of capacitors for Delta SMP-220DB PSU (Apple P/N 614-0012)"], principally the capacitor list posted by croissantking (with his later correction of C253 to 220 µF) and the repair notes from mitchW. Secondary source: members' direct readings from their own supplies. Source for the SMP-220DB board breakdown and capacitor list, for the 105 °C / 85 °C ratings, for R955A and R955B being 180 Ω 0.125 W, for ZD1 and ZD2 being 18 V, for the PWR_ON latching behaviour, and for the safety-capacitor incident described here.</ref> Reflow every joint you disturbed before the unit sees mains again.
 
There is no CRT in the system unit — see [[CRT Discharge Procedure]] only if you are working on a monitor.
 
== What Actually Fails ==


* '''System instability''' — Random crashes, freezes, or failure to boot
* '''The logic board is reported to carry solid (tantalum) capacitors, not surface-mount aluminium electrolytics.''' A 68kMLA member describes his Quadra 800 as having "solid capacitors", explicitly contrasting it with the [[Macintosh Quadra 840AV|840AV]], and members of the same thread group the Quadra 800 with the [[Macintosh Centris 650|Centris 650]] and Quadra 650 as the "Wombat" board family — where two further members report tantalum and ceramic parts on their own boards.<ref name="mla800">68kMLA forum thread [https://68kmla.org/bb/threads/quadra-800.46448/ "Quadra 800"], posts by sunaiac and Phipli. Secondary source: an owner's description of his own machine as having solid capacitors, and the identification of the Quadra 800, Quadra 640 and Centris 650 as one board family.</ref><ref name="mla650">68kMLA forum thread [https://68kmla.org/bb/index.php?threads/capacitors-for-centris-650.2544/ "Capacitors for Centris 650"], posts by Simon_Carr and 360alaska. Secondary source: two members' direct inspection of their own Centris 650 boards, reporting tantalum and ceramic capacitors on the logic board.</ref> This is community observation, not an Apple statement, and it rests on fewer reports than the equivalent claim for the Centris 650. '''Check your own board before deciding not to recap it.''' Aluminium surface-mount electrolytics are small metal cans on a plastic base; tantalums are solid moulded blocks, usually amber or dark brown.
* '''Audio distortion''' — Crackling, humming, or no audio output
* '''Tantalums fail short.''' A shorted decoupling part drags its rail down and the supply shuts down or a fuse goes. Look for a cracked or scorched block, and for a rail that reads as a short to ground with the supply disconnected.
* '''Video problems''' — Distortion, incorrect colors, or no video
* '''The power supply is where the electrolytics are''', and where the age-related failures happen.
* '''Power issues''' — Difficulty starting or staying powered on
* '''Age''' — The system is over 25 years old


== Capacitor Inspection ==
'''Apple published no capacitor values for this machine.''' The Service Source contains no capacitance, working-voltage or designator data anywhere; every power fault in the symptom charts ends in "Replace power supply."<ref name="ss800" /> Everything below is community data from a named source.


Before recapping, inspect existing capacitors for:
== The Power Supply ==


* '''Bulging Tops''' — Electrolytic capacitors should have flat tops; bulging indicates failure
The Quadra 800 uses the '''Delta SMP-220DB''', Apple part number '''614-0012'''. The same unit is fitted to the [[Macintosh Quadra 840AV]] and the Power Macintosh 8100/80.<ref name="mla220db" />
* '''Leaking Electrolyte''' — Brown or black residue around capacitor base
* '''Corrosion or PCB Staining''' — Discoloration on the PCB near capacitors
* '''Physical Damage''' — Cracked cases or bent leads


== Macintosh Quadra 800 Logic Board Capacitors ==
It is built as five stacked sub-boards, four of which carry electrolytics. The list below was compiled by a 68kMLA member who dismantled a unit completely and recorded the designator, value and physical size of every part, and later corrected one entry (C253) in the same thread. All the electrolytics are 105 °C parts except the two bulk capacitors C1 and C2, which are 85 °C.<ref name="mla220db" />


The Quadra 800 logic board contains through-hole electrolytic capacitors. Common values include:
{| class="wikitable styled-table" style="width:100%;"
<templatestyles src="Template:StyledTable/styles.css" />
|-
{| class="wikitable styled-table" style="width:100%; text-align:center;"
! Board !! Designator !! Value !! Size (length × dia.)
|+ '''Logic Board Capacitor Specifications'''
|-
| SMP-220DP-1 || C104, C105 || 3300 µF 10 V || 36 × 13 mm
|-
| SMP-220DP-1 || C106 || 2200 µF 10 V || 28 × 13 mm
|-
| SMP-220DP-1 || C107 || 1000 µF 10 V || 20 × 10 mm
|-
| SMP-220DP-1 || C154, C156 || 1000 µF 16 V || 28 × 10 mm
|-
| SMP-220DP-1 || C252, C807 || 470 µF 35 V || 20 × 10 mm
|-
| SMP-220DP-1 || C253 || 220 µF 16 V || 15 × 18 mm
|-
| SMP-220DP-1 || C513 || 10 µF 50 V || 11 × 5 mm
|-
| SMP-220DP || C1, C2 || 820 µF 200 V || 40 × 30 mm
|-
| SMP-220DP || C301 || 470 µF 35 V || 20 × 10 mm
|-
| SMP-220DP || C302 || 0.47 µF 50 V || 11 × 5 mm
|-
| SMP-220DP || C304 || 4.7 µF 50 V || 11 × 5 mm
|-
| SMP-220DP || C952 || 1 µF 50 V || 11 × 5 mm
|-
| DC-267 || C507 || 2.2 µF 50 V || 11 × 5 mm
|-
|-
! Location !! Capacitance !! Voltage !! Type !! Notes
| DC-267 || C511 || 22 µF 50 V || 11 × 5 mm
|-
|-
| Various || 47µF || 16V || Electrolytic || Audio/power filtering
| DC-267 || C532, C601 || 10 µF 50 V || 11 × 5 mm
|-
|-
| Various || 100µF || 16V || Electrolytic || Power rail filtering
| DC-267 || C655, C674 || 4.7 µF 50 V || 11 × 5 mm
|-
|-
| Various || 10µF || 16V || Electrolytic || Signal coupling
| DC-267 || C783 || 1 µF 50 V || 11 × 5 mm
|-
|-
| Various || 220µF || 16V || Electrolytic || Power filtering
| DC-267 || C784 || 100 µF 25 V || 11 × 7 mm
|-
|-
| Various || 1000µF || 16V || Electrolytic || Main power filtering
| DC-230 || C804 || 2.2 µF 50 V || 11 × 5 mm
|}
|}


'''Note:''' Exact capacitor locations and values should be verified against your specific board revision. Take photos before desoldering to document original positions and polarities.
This is a secondary source and covers one physical unit. Read the markings on your own supply before ordering — and note that "SMP-220DP" appears on the boards while the unit as a whole is labelled SMP-220DB.


== Power Supply Capacitors ==
=== The 200 V bulk pair ===


The Quadra 800 power supply contains several electrolytic capacitors that may also need replacement. '''Warning:''' Power supplies contain hazardous voltages. Allow the unit to discharge for at least 24 hours after unplugging before servicing.
C1 and C2 are '''in series across the rectified mains'''. That is how a 200 V part survives in a supply rated for 100–240 V input: on 230–240 V mains the DC bus sits at roughly 340 V, and only the series pair holds it off.


Common power supply capacitor values include:
* '''Never fit a single capacitor in place of the pair.''' One 200 V part in that position will fail on European mains, violently.
* Large filter capacitors (200V+ rated)
* Replace both together with matched parts of the same value and voltage, or higher.
* Secondary filtering capacitors (various values)
* These two are also the parts that hold their charge longest. Discharge them first and check them last.


If you're not experienced with power supply repair, consider having the PSU serviced by a professional.
== Things That Are Not Capacitors ==


== Capacitor Replacement Procedure ==
Recapping this supply frequently does not fix it. Two failures documented in the same thread are worth checking before you order parts:<ref name="mla220db" />


# '''Prepare the workspace''' — Use an ESD mat and wrist strap; ensure good lighting
* '''R955A and R955B''' on the control board — '''180 Ω, 0.125 W'''. Both had burned open on one unit, taking the supply with them. The markings burn off, so there is no way to read the value from a failed part.
# '''Remove the logic board''' — Document cable positions; carefully release plastic clips
* '''ZD1 and ZD2''' — '''18 V''' zener diodes. If these are blown, the primary switching transistors have very likely gone too.
# '''Photograph the board''' — Record capacitor positions and polarities before removal
* A '''failed LM339N comparator''' on the control board brought one otherwise-dead unit straight back to life after a full recap had achieved nothing. The PS_ON signal connects directly to one of its pins.
# '''Desolder old capacitors''' — Use a temperature-controlled soldering iron (300-350°C) and desoldering pump or wick
# '''Clean pads''' — Remove old solder and flux residue with isopropyl alcohol
# '''Install replacements''' — Observe correct polarity (negative stripe aligns with board markings); use quality capacitors rated for 105°C
# '''Solder securely''' — Ensure good solder joints with proper wetting
# '''Trim leads''' — Cut excess lead length flush with solder joint
# '''Clean board''' — Remove flux residue with isopropyl alcohol and ESD-safe brush
# '''Inspect work''' — Check for solder bridges, cold joints, or incorrect polarity
# '''Test before reassembly''' — Power on the board outside the case to verify operation


== Recommended Replacement Capacitors ==
=== Soft power behaviour ===


Use high-quality capacitors from reputable manufacturers:
This supply is not an ATX unit and does not behave like one. PWR_ON '''latches on''' when it is pulled up to the +5 V trickle rail, and the supply will run with PWR_ON left unconnected. To shut it down you short PWR_ON '''to ground''' — the opposite of ATX.<ref name="mla220db" /> Bench-testing it with ATX assumptions will make a working supply look dead.


* '''Nichicon''' — UPW, UHE, or UPM series
The +5 V trickle rail is the first useful measurement on a dead machine: present means the primary side is alive and the fault is downstream; absent means the mains input, the primary switcher or the standby circuit.
* '''Panasonic''' — FR, FC, or FM series
* '''Rubycon''' — ZLH or YXF series
* '''United Chemi-Con''' — KZE or KY series


Match or exceed original specifications:
== Replacement Procedure ==
* Same or higher capacitance
* Same or higher voltage rating
* 105°C temperature rating preferred
* Low ESR types for power supply applications


== Recommended Tools ==
# Discharge the bulk capacitors and confirm with a meter.
# Photograph every board before separating them. The five boards interlock and the inter-board pins only go back one way.
# Desolder with a temperature-controlled iron and a pump or wick. The bulk capacitors sit on heavy copper and need dwell time.
# Clean the pads with isopropyl alcohol. Expect generous, erratically placed silicone adhesive; soften it with isopropyl alcohol and cut it away with a scalpel rather than pulling.
# Fit the replacements the right way round — on aluminium electrolytics the stripe marks the '''negative''' lead.
# '''Reflow every joint you disturbed''', including the inter-board pins, before the unit goes anywhere near mains.
# Bring it up behind a series lamp — a 100 W or 200 W filament bulb in place of the fuse — on a dummy load, before connecting it to the logic board.


* Temperature-controlled soldering iron (Hakko, Weller, or similar)
Use 105 °C, low-ESR parts rated for switching-supply ripple. See [[Recommended Tools]].
* Desoldering pump (solder sucker) or desoldering braid/wick
* Fine leaded solder (0.5-0.8mm, 63/37 tin-lead preferred)
* Flux pen or liquid flux
* Isopropyl alcohol (90% or higher)
* ESD-safe brushes
* Multimeter with capacitance testing
* Safety glasses
* ESD mat and wrist strap


== Post-Recap Testing ==
== Logic Board ==


After recapping:
No preventive recap is required if your board is a tantalum one. If a tantalum has failed, replace it with the same capacitance and generous derating: solid tantalums want about 50 % voltage derating, so a part on a 5 V rail needs a 10 V or higher rating and one on 12 V needs 25 V.<ref name="tdtant">TinkerDifferent forum thread [https://tinkerdifferent.com/threads/tantalum-vs-electrolytic-can-i-just-always-use-tantalum.4077/ "Tantalum vs Electrolytic. Can I just always use tantalum?"], posts by Nycturne, Phipli and JDW. Secondary source. Used here for the 50 % voltage derating rule for solid tantalums, for the short-circuit failure mode, and for the note that polymer types fail benignly.</ref> Polymer parts are a good substitute and fail benignly.


# '''Visual inspection''' — Check all solder joints and polarities
Remember the polarity convention flips: on an aluminium electrolytic the stripe is '''negative'''; on a tantalum the bar is '''positive'''.
# '''Continuity test''' — Verify no shorts between power rails and ground
# '''Voltage test''' — Power on and measure voltages at test points
# '''Functional test''' — Boot system and test all functions
# '''Burn-in''' — Run system for several hours to verify stability


== Voltage Adjustment After Recap ==
See [[Capacitor Failure Symptoms]] for what failure looks like elsewhere in the machine.


After replacing power supply capacitors, verify and adjust voltages if necessary:
== Battery ==


* '''+5V rail:''' 4.85V – 5.15V
Apple's documented check: set a voltmeter to the 10 V DC range, measure across the cell in its holder, and '''replace it if it reads below 3.2 V'''.<ref name="ss800" /> The cell sits in a latched holder and is not soldered in.
* '''+12V rail:''' 11.9V – 12.7V


Some power supplies have adjustment potentiometers for fine-tuning voltages.
Apple lists a battery check among the steps for intermittent shutdowns, because the cell is part of the soft-power circuit.<ref name="ss800" /> A leaking cell will corrode the traces beneath the holder — see [[Battery Explosion, Capacitor or Corrosion Damage]].


== Additional Tips ==
== Electrical Specification and What Apple Does Not Publish ==


* Take your time — rushing leads to mistakes
Apple's specification: '''100–240 V AC, 50–60 Hz single phase, 200 W continuous.'''<ref name="ss800" /> The supply is self-configuring, so there is no voltage selector to set wrongly.
* Work on one capacitor at a time to avoid confusion
* If a pad lifts, it can often be repaired with thin wire
* Keep the old capacitors until the system is verified working
* Consider upgrading to polymer or solid capacitors where appropriate
* Document your work with photos for future reference


== Related Maintenance Pages ==
'''Apple publishes no rail tolerance band and no power-supply adjustment procedure for this machine.''' There is no adjustment chapter in the Service Source and no potentiometer to turn. If a rail is out, the supply is faulty; there is nothing to trim.


Apple's symptom charts send the following to the power supply:<ref name="ss800" />
* Dead machine — black screen, fan not turning, LED not lit, after checking cables and the mains lead.
* Clicking, chirping or thumping noises.
* Intermittent shutdowns not explained by blocked vents or a flat battery. Apple notes that the thermal protection circuit will shut the machine down when the vents are obstructed, and that it recovers after 30 to 40 minutes — that is normal behaviour, not a fault.
== Related Pages ==
* [[Macintosh Quadra 800]]
* [[Macintosh Quadra 800 Troubleshooting]]
* [[Macintosh Quadra 800 Troubleshooting]]
* [[Macintosh Quadra 800 General Maintenance]]
* [[Macintosh Quadra 800 General Maintenance]]
* [[Macintosh Quadra 800]]
* [[Macintosh Quadra 840AV Capacitor Replacement Guide]] — same power supply
* [[Capacitor Failure Symptoms]]
* [[Recommended Tools]]
 
== References ==
 
<references />
 
{{Navbox-AppleVintage|state=collapsed}}


[[Category:Apple Vintage Computers]]
[[Category:Apple Vintage Computers]]
[[Category: Capacitor Replacement Guides]]
[[Category: Capacitor Replacement Guides]]

Latest revision as of 01:15, 23 September 2026

Macintosh Quadra 800

This guide covers capacitor diagnosis and replacement on the Macintosh Quadra 800 and the Workgroup Server 80, which share one logic board, one enclosure and one power supply.[1]

On this machine the work is in the power supply. The logic board is a different design from the leaking surface-mount boards of the same period.

Safety

[edit | edit source]

The supply is a mains-rectified switcher. Its primary side sits at mains potential and the two 200 V bulk capacitors hold a charge that can kill after the machine is unplugged. Recapping it is a reasonable job, but treat it as live-mains work:

  1. Switch off and unplug the mains lead.
  2. Discharge each bulk capacitor through a 1 kΩ / 5 W resistor across its terminals and confirm with a meter that it reads near zero.
  3. Work one-handed where practical, and do not probe a powered primary side without an isolation transformer.

This supply comes apart into five stacked boards, which means components on the primary side end up exposed and easy to reach across. One member who reassembled it with a joint left unsoldered had the mains-side safety capacitors detonate when he plugged it in — nothing caught fire, but it was loud and it could have been much worse.[2] Reflow every joint you disturbed before the unit sees mains again.

There is no CRT in the system unit — see CRT Discharge Procedure only if you are working on a monitor.

What Actually Fails

[edit | edit source]
  • The logic board is reported to carry solid (tantalum) capacitors, not surface-mount aluminium electrolytics. A 68kMLA member describes his Quadra 800 as having "solid capacitors", explicitly contrasting it with the 840AV, and members of the same thread group the Quadra 800 with the Centris 650 and Quadra 650 as the "Wombat" board family — where two further members report tantalum and ceramic parts on their own boards.[3][4] This is community observation, not an Apple statement, and it rests on fewer reports than the equivalent claim for the Centris 650. Check your own board before deciding not to recap it. Aluminium surface-mount electrolytics are small metal cans on a plastic base; tantalums are solid moulded blocks, usually amber or dark brown.
  • Tantalums fail short. A shorted decoupling part drags its rail down and the supply shuts down or a fuse goes. Look for a cracked or scorched block, and for a rail that reads as a short to ground with the supply disconnected.
  • The power supply is where the electrolytics are, and where the age-related failures happen.

Apple published no capacitor values for this machine. The Service Source contains no capacitance, working-voltage or designator data anywhere; every power fault in the symptom charts ends in "Replace power supply."[1] Everything below is community data from a named source.

The Power Supply

[edit | edit source]

The Quadra 800 uses the Delta SMP-220DB, Apple part number 614-0012. The same unit is fitted to the Macintosh Quadra 840AV and the Power Macintosh 8100/80.[2]

It is built as five stacked sub-boards, four of which carry electrolytics. The list below was compiled by a 68kMLA member who dismantled a unit completely and recorded the designator, value and physical size of every part, and later corrected one entry (C253) in the same thread. All the electrolytics are 105 °C parts except the two bulk capacitors C1 and C2, which are 85 °C.[2]

Board Designator Value Size (length × dia.)
SMP-220DP-1 C104, C105 3300 µF 10 V 36 × 13 mm
SMP-220DP-1 C106 2200 µF 10 V 28 × 13 mm
SMP-220DP-1 C107 1000 µF 10 V 20 × 10 mm
SMP-220DP-1 C154, C156 1000 µF 16 V 28 × 10 mm
SMP-220DP-1 C252, C807 470 µF 35 V 20 × 10 mm
SMP-220DP-1 C253 220 µF 16 V 15 × 18 mm
SMP-220DP-1 C513 10 µF 50 V 11 × 5 mm
SMP-220DP C1, C2 820 µF 200 V 40 × 30 mm
SMP-220DP C301 470 µF 35 V 20 × 10 mm
SMP-220DP C302 0.47 µF 50 V 11 × 5 mm
SMP-220DP C304 4.7 µF 50 V 11 × 5 mm
SMP-220DP C952 1 µF 50 V 11 × 5 mm
DC-267 C507 2.2 µF 50 V 11 × 5 mm
DC-267 C511 22 µF 50 V 11 × 5 mm
DC-267 C532, C601 10 µF 50 V 11 × 5 mm
DC-267 C655, C674 4.7 µF 50 V 11 × 5 mm
DC-267 C783 1 µF 50 V 11 × 5 mm
DC-267 C784 100 µF 25 V 11 × 7 mm
DC-230 C804 2.2 µF 50 V 11 × 5 mm

This is a secondary source and covers one physical unit. Read the markings on your own supply before ordering — and note that "SMP-220DP" appears on the boards while the unit as a whole is labelled SMP-220DB.

The 200 V bulk pair

[edit | edit source]

C1 and C2 are in series across the rectified mains. That is how a 200 V part survives in a supply rated for 100–240 V input: on 230–240 V mains the DC bus sits at roughly 340 V, and only the series pair holds it off.

  • Never fit a single capacitor in place of the pair. One 200 V part in that position will fail on European mains, violently.
  • Replace both together with matched parts of the same value and voltage, or higher.
  • These two are also the parts that hold their charge longest. Discharge them first and check them last.

Things That Are Not Capacitors

[edit | edit source]

Recapping this supply frequently does not fix it. Two failures documented in the same thread are worth checking before you order parts:[2]

  • R955A and R955B on the control board — 180 Ω, 0.125 W. Both had burned open on one unit, taking the supply with them. The markings burn off, so there is no way to read the value from a failed part.
  • ZD1 and ZD2 — 18 V zener diodes. If these are blown, the primary switching transistors have very likely gone too.
  • A failed LM339N comparator on the control board brought one otherwise-dead unit straight back to life after a full recap had achieved nothing. The PS_ON signal connects directly to one of its pins.

Soft power behaviour

[edit | edit source]

This supply is not an ATX unit and does not behave like one. PWR_ON latches on when it is pulled up to the +5 V trickle rail, and the supply will run with PWR_ON left unconnected. To shut it down you short PWR_ON to ground — the opposite of ATX.[2] Bench-testing it with ATX assumptions will make a working supply look dead.

The +5 V trickle rail is the first useful measurement on a dead machine: present means the primary side is alive and the fault is downstream; absent means the mains input, the primary switcher or the standby circuit.

Replacement Procedure

[edit | edit source]
  1. Discharge the bulk capacitors and confirm with a meter.
  2. Photograph every board before separating them. The five boards interlock and the inter-board pins only go back one way.
  3. Desolder with a temperature-controlled iron and a pump or wick. The bulk capacitors sit on heavy copper and need dwell time.
  4. Clean the pads with isopropyl alcohol. Expect generous, erratically placed silicone adhesive; soften it with isopropyl alcohol and cut it away with a scalpel rather than pulling.
  5. Fit the replacements the right way round — on aluminium electrolytics the stripe marks the negative lead.
  6. Reflow every joint you disturbed, including the inter-board pins, before the unit goes anywhere near mains.
  7. Bring it up behind a series lamp — a 100 W or 200 W filament bulb in place of the fuse — on a dummy load, before connecting it to the logic board.

Use 105 °C, low-ESR parts rated for switching-supply ripple. See Recommended Tools.

Logic Board

[edit | edit source]

No preventive recap is required if your board is a tantalum one. If a tantalum has failed, replace it with the same capacitance and generous derating: solid tantalums want about 50 % voltage derating, so a part on a 5 V rail needs a 10 V or higher rating and one on 12 V needs 25 V.[5] Polymer parts are a good substitute and fail benignly.

Remember the polarity convention flips: on an aluminium electrolytic the stripe is negative; on a tantalum the bar is positive.

See Capacitor Failure Symptoms for what failure looks like elsewhere in the machine.

Battery

[edit | edit source]

Apple's documented check: set a voltmeter to the 10 V DC range, measure across the cell in its holder, and replace it if it reads below 3.2 V.[1] The cell sits in a latched holder and is not soldered in.

Apple lists a battery check among the steps for intermittent shutdowns, because the cell is part of the soft-power circuit.[1] A leaking cell will corrode the traces beneath the holder — see Battery Explosion, Capacitor or Corrosion Damage.

Electrical Specification and What Apple Does Not Publish

[edit | edit source]

Apple's specification: 100–240 V AC, 50–60 Hz single phase, 200 W continuous.[1] The supply is self-configuring, so there is no voltage selector to set wrongly.

Apple publishes no rail tolerance band and no power-supply adjustment procedure for this machine. There is no adjustment chapter in the Service Source and no potentiometer to turn. If a rail is out, the supply is faulty; there is nothing to trim.

Apple's symptom charts send the following to the power supply:[1]

  • Dead machine — black screen, fan not turning, LED not lit, after checking cables and the mains lead.
  • Clicking, chirping or thumping noises.
  • Intermittent shutdowns not explained by blocked vents or a flat battery. Apple notes that the thermal protection circuit will shut the machine down when the vents are obstructed, and that it recovers after 30 to 40 minutes — that is normal behaviour, not a fault.
[edit | edit source]

References

[edit | edit source]
  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Apple Computer, Macintosh Quadra 800/WS 80 Service Source — hosted on this wiki as File:Quadra_800.ws_80.pdf. Chapters used here: Specifications (Processor, Electrical), Troubleshooting (Symptom Charts) and Additional Procedures (Battery Verification, Battery Replacement).
  2. ↑ 2.0 2.1 2.2 2.3 2.4 68kMLA forum thread "In search of list of capacitors for Delta SMP-220DB PSU (Apple P/N 614-0012)", principally the capacitor list posted by croissantking (with his later correction of C253 to 220 µF) and the repair notes from mitchW. Secondary source: members' direct readings from their own supplies. Source for the SMP-220DB board breakdown and capacitor list, for the 105 °C / 85 °C ratings, for R955A and R955B being 180 Ω 0.125 W, for ZD1 and ZD2 being 18 V, for the PWR_ON latching behaviour, and for the safety-capacitor incident described here.
  3. ↑ 68kMLA forum thread "Quadra 800", posts by sunaiac and Phipli. Secondary source: an owner's description of his own machine as having solid capacitors, and the identification of the Quadra 800, Quadra 640 and Centris 650 as one board family.
  4. ↑ 68kMLA forum thread "Capacitors for Centris 650", posts by Simon_Carr and 360alaska. Secondary source: two members' direct inspection of their own Centris 650 boards, reporting tantalum and ceramic capacitors on the logic board.
  5. ↑ TinkerDifferent forum thread "Tantalum vs Electrolytic. Can I just always use tantalum?", posts by Nycturne, Phipli and JDW. Secondary source. Used here for the 50 % voltage derating rule for solid tantalums, for the short-circuit failure mode, and for the note that polymer types fail benignly.


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