Macintosh Quadra 800 Capacitor Replacement Guide
The Macintosh Quadra 800 and the Workgroup Server 80 share one logic board, one case and one power supply.[1] The electrolytics that need replacing are in the power supply. Apple's Service Source gives no capacitor values for either board, and every power fault in its symptom charts ends in "replace power supply".[1]
Logic board
[edit | edit source]Owners describe the Quadra 800 logic board as built with tantalum capacitors. A TinkerDifferent member found "all tantalum caps" on his board, and another replied that the Centris and Quadra 650 and Quadra 800 boards came with tantalums from the factory.[2] MacDat says the board uses solid capacitors throughout and should not need recapping, while the supply often does.[3] A 68kMLA member describes his board the same way, in contrast to the Quadra 840AV, and members of that thread group it with the Centris 650 board family.[4] These are owners' reports, not Apple documentation, so check your own board before deciding it needs no work. Aluminium surface-mount electrolytics are small metal cans on a plastic base; tantalums are moulded blocks, usually amber or dark brown.
Solid tantalums do not leak, but they fail short, which pulls the rail down and makes the supply shut down or blow a fuse. If one has to be replaced, derate it by about half: a tantalum on a 5 V rail needs a 10 V or higher rating, one on 12 V needs 25 V. Polymer types do not fail short.[5] On an aluminium electrolytic the stripe marks the negative lead; on a tantalum the bar marks the positive lead. See Capacitor Failure Symptoms.
Power supply
[edit | edit source]The Quadra 800 and Quadra 840AV use the same power supply, Apple service part 661-1687, rated at 200 W continuous on a 100-240 V AC input.[1][6] Apple's module identification manual gives 614-0012 as the assembly number on the label of the 661-1687 supply,[7] and Apple Rescue of Denver lists the same unit as 614-0012, fitted to the Power Macintosh 8100 as well, and says it was made by several manufacturers, including Delta and Magnetek.[8] Read the maker's label before ordering parts: the list below is for the Delta unit only.
The primary side runs at mains potential, and the 200 V reservoir capacitors C1 and C2 hold a charge after the machine is unplugged. Discharge them and confirm with a meter before touching the board.
Delta SMP-220DB capacitor list
[edit | edit source]The Delta unit is labelled SMP-220DB (the boards are marked SMP-220DP) and is built as five stacked boards, four of which carry electrolytics. The list below was compiled on 68kMLA by a member who dismantled one unit and recorded every electrolytic, with a later correction to C253. All are 105 °C parts except C1 and C2, which are 85 °C.[9]
| Board | Ref | Value | Size (length × diameter) |
|---|---|---|---|
| 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 |
Replace C1 and C2 together with parts of the same value and at least 200 V.
Faults that are not capacitors
[edit | edit source]The same thread records these failures on units where a recap alone did not help:[9]
- R955A and R955B on the control board, both 180 Ω 0.125 W, burned open. Their markings burn off, so the value cannot be read from a failed part.
- ZD1 and ZD2, 18 V zener diodes. If they have failed, check the primary switching transistors too.
- A failed LM339N comparator on the control board; replacing it revived a supply that a full recap had not. The PWR_ON signal connects to one of its pins.
The supply latches on when PWR_ON is pulled up to the +5 V trickle rail and runs with PWR_ON unconnected; it shuts down when PWR_ON is taken to ground. This is not ATX behaviour, so bench-test it on those terms.[9]
Removal and recap
[edit | edit source]- Unplug the machine. Loosen the four captive cover screws, slide the cover forward about 1/2 inch and lift it off.[1]
- Remove the chassis support brace, disconnect the logic board power cable, press the latch, slide the supply forward and pull it out.[1]
- Discharge C1 and C2 and confirm with a meter.
- Photograph each board before separating them; the inter-board pins go back only one way.
- Replace the capacitors, observing polarity. The boards carry silicone adhesive; soften it with isopropyl alcohol and cut it away.
- Reflow every joint you disturbed, including the inter-board pins. On the 68kMLA thread, a unit reassembled with one joint left unsoldered blew its mains-side safety capacitors when it was plugged in.[9]
- Bring the supply up on a dummy load, ideally through a series lamp, before connecting it to the logic board.
Battery
[edit | edit source]The PRAM battery is a lithium cell in a latched holder. Apple's check is made with the cover and logic board removed: set the voltmeter to the 10 V DC range, measure across the cell and replace it below 3.2 V.[1] A leaking cell corrodes the traces under the holder; see Battery Explosion, Capacitor or Corrosion Damage.
After the recap
[edit | edit source]Apple's specification is 100-240 V AC, 50-60 Hz single phase, 200 W continuous.[1] The Service Source has no rail tolerance table and no adjustment procedure. Check the +5 V and +12 V rails at a drive power connector against nominal and look for a rail that sags or is unstable when a drive spins up.
Apple's symptom charts send three faults to the power supply: a machine that does not power on at all (screen black, fan not running, LED not lit) once the power cables, the monitor's own power and the mains lead have been checked; clicking, chirping or thumping noises (power supply, then logic board, then the floppy drive cable and floppy drive); and intermittent shutdowns not explained by blocked vents, the mains lead or the battery. Blocked vents make the thermal protection circuit shut the system down; it should work again after 30 to 40 minutes.[1]
Related pages
[edit | edit source]- Macintosh Quadra 800
- Macintosh Quadra 800 Troubleshooting
- Macintosh Quadra 800 General Maintenance
- Macintosh Quadra 840AV Capacitor Replacement Guide (same power supply)
- Capacitor Failure Symptoms
- Recommended Tools
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Apple Computer, Macintosh Quadra 800/WS 80 Service Source. Hosted here as Macintosh Quadra 800/WS 80 Service Source (File:Quadra_800.ws_80.pdf). Specifications, Electrical (PDF p. 11); Troubleshooting, Symptom Charts (pp. 16-18); Take Apart, Cover (p. 33) and Power Supply (pp. 47-51); Additional Procedures, Battery Verification (pp. 75-76); Exploded View (p. 81, power supply 661-1687).
- ↑ TinkerDifferent forum thread "A 'NEW' quadra 800?", July 2022: -SE40- finds "all tantalum caps" on a Quadra 800 logic board; Volvo242GT replies that the Centris/Quadra 650 and Quadra 800 boards came with tantalums from the factory. Secondary source.
- ↑ Macintosh Quadra 800, MacDat—link(accessed 2026-10-12) "Capacitors" section: the logic board uses solid capacitors throughout and should not need recapping; the power supply often does. Secondary source.
- ↑ 68kMLA forum thread "Quadra 800", posts by sunaiac and Phipli. Secondary source: an owner's description of his own board.
- ↑ TinkerDifferent forum thread "Tantalum vs Electrolytic. Can I just always use tantalum?" (retrieved 2026-09-30). Secondary source for the 50 per cent voltage derating of solid tantalums, their short-circuit failure mode and the benign failure of polymer types.
- ↑ Apple Computer, Macintosh Quadra 840AV Service Source. Hosted here as Macintosh Quadra 840AV Service Source (File:Quadra_840av.pdf). Exploded View (PDF p. 86): power supply 661-1687.
- ↑ Apple Computer, Module Identification, part number 072-8124, June 1994, p. 3.8.3 (PDF page 211): "Macintosh Power Supply, 200 Watt", Apple P/N 661-1687, with assembly number 614-0012 on the module label. Hosted as File:Apple Service Module Identification Manual (June 1994).pdf.
- ↑ Apple Rescue of Denver, "Power Macintosh 8100, 8150 - Power Supply" (retrieved 2026-09-30): "200W Power Supply - 661-1687, 661-0232, 614-0012. Several manufacturers including Delta and Magnetek."
- ↑ 9.0 9.1 9.2 9.3 68kMLA forum thread "In search of list of capacitors for Delta SMP-220DB PSU (Apple P/N 614-0012)", capacitor list posted by croissantking (with his correction of C253 to 220 µF) and repair notes from mitchW. Secondary source: members' readings from their own supplies. Source for the board breakdown, capacitor list and temperature ratings, R955A/R955B, ZD1/ZD2, the LM339N fault, the PWR_ON behaviour and the safety-capacitor failure after reassembly.