Josh: Added Capacitor_Replacement_Guides category

2026-02-11T15:12:20Z

Added Capacitor_Replacement_Guides category

← Older revision		Revision as of 16:12, 11 February 2026
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	[[Category:Apple Vintage Computers]]		[[Category:Apple Vintage Computers]]
	[[Category:Apple Capacitor Guides]]		[[Category:Apple Capacitor Guides]]
			[[Category:Capacitor_Replacement_Guides]]

Josh: Added recap guide image from Recap-a-Mac

2026-02-09T11:25:18Z

Added recap guide image from Recap-a-Mac

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	\| 11 \|\| 47 µF \|\| 16V \|\| SMD electrolytic \|\| Surface-mount, prone to leakage		\| 11 \|\| 47 µF \|\| 16V \|\| SMD electrolytic \|\| Surface-mount, prone to leakage
	\|}		\|}

			[[File:Mac_IIsi_Recap_Guide.jpg\|center\|thumb\|600px\|Macintosh IIsi logic board capacitor locations. Source: Recap-a-Mac]]

	=== Replacement Options ===		=== Replacement Options ===

Josh: Created Macintosh IIsi Capacitor Replacement Guide

2026-02-09T11:09:18Z

Created Macintosh IIsi Capacitor Replacement Guide

New page

The '''Macintosh IIsi''' logic board and power supply contain surface-mount electrolytic capacitors that are prone to leakage after 30+ years of age. This guide provides detailed specifications and procedures for capacitor replacement ("recapping").

== Why Recap? ==

Electrolytic capacitors use a liquid or gel electrolyte that can leak over time due to:
* Natural aging of the component sealing
* Internal corrosion within the capacitor
* Storage conditions (heat and humidity accelerate degradation)

The leaked electrolyte is both '''conductive''' and '''corrosive''':
* '''Conductive''': Creates short circuits between traces, causing erratic behavior or complete failure
* '''Corrosive''': Eats through copper traces and attacks solder joints, potentially destroying the board beyond repair

Proactive recapping before leakage occurs will prevent irreversible damage.

== Logic Board Capacitors ==

The Macintosh IIsi logic board contains '''13 electrolytic capacitors''':<ref>{{cite web |url=https://68kmla.org/bb/threads/caps-macintosh-iisi.26708/ |title=Caps! -- Macintosh IIsi |publisher=68kMLA |access-date=2026-02-09}}</ref>

<templatestyles src="Template:StyledTable/styles.css" />
{| class="wikitable styled-table" style="width:90%; text-align:center;"
|+ '''Macintosh IIsi Logic Board Capacitor List'''
|-
! Quantity !! Capacitance !! Voltage !! Package Type !! Notes
|-
| 2 || 220 µF || 16V || Axial electrolytic || Main filter capacitors
|-
| 11 || 47 µF || 16V || SMD electrolytic || Surface-mount, prone to leakage
|}

=== Replacement Options ===

==== Electrolytic (Original Style) ====
{| class="wikitable styled-table" style="width:90%; text-align:center;"
|-
! Spec !! Mouser Part Number !! Notes
|-
| 220 µF 16V Axial || Nichicon TVX1E221MAD || Stock-like appearance
|-
| 220 µF 16V Radial || EPCOS B41828A5227M8 || Lower cost alternative (mount flat)
|-
| 47 µF 16V SMD || Standard SMD electrolytic || Available from various manufacturers
|}

==== Tantalum (Recommended) ====
Tantalum capacitors use a '''solid electrolyte''' that cannot leak, eliminating future leakage concerns:<ref>{{cite web |url=https://www.edretrotech.com/2020/12/recapping-macintosh-se30-and-iisi-logic.html |title=Recapping a Macintosh SE/30 and a IIsi |publisher=ED Retro Tech |access-date=2026-02-09}}</ref>

{| class="wikitable styled-table" style="width:90%; text-align:center;"
|-
! Spec !! Recommended Replacement !! Notes
|-
| 47 µF 16V || Tantalum SMD (AVX, KEMET, Vishay) || Leak-proof; slightly larger footprint
|-
| 220 µF 16V || Tantalum axial or polymer electrolytic || May need to adjust for size
|}

'''Note:''' Tantalum capacitors are polarized and can fail catastrophically (short circuit) if installed backwards. Always verify polarity before soldering.

==== Polymer/Hybrid ====
Modern polymer electrolytic capacitors offer:
* No liquid electrolyte (won't leak)
* Lower ESR than tantalum
* Smaller size than tantalum equivalents

Panasonic OS-CON or similar polymer electrolytics are excellent choices where they fit.

== Power Supply Capacitors ==

The IIsi uses a Sony 160W power supply that also requires recapping. '''Warning:''' Power supplies contain high-voltage capacitors that can retain a lethal charge. Discharge all capacitors before servicing.

=== Known Power Supply Capacitors ===
Power supply capacitor values may vary by PSU revision. Common values include:

{| class="wikitable styled-table" style="width:90%; text-align:center;"
|+ '''Macintosh IIsi Power Supply Capacitors (typical)'''
|-
! Quantity !! Capacitance !! Voltage !! Package Type !! Location
|-
| 2 || 470 µF || 200V || Radial || Primary side (high voltage!)
|-
| 1 || 2200 µF || 25V || Radial || Secondary side
|-
| 1 || 47 µF || 100V || Radial || Secondary side
|-
| 2 || 10 µF || 25-50V || Radial || Various
|}

'''Important:''' Always verify capacitor values against your specific unit before ordering. Some power supplies may have different revisions with different values.

== Tools Required ==

* Soldering iron with fine tip (Hakko FX-600 or similar recommended)
* Hot air rework station (for SMD removal)
* Solder (60/40 or 63/37 leaded, 0.5-0.8mm)
* Flux (no-clean or rosin)
* Solder wick and/or desoldering pump
* Isopropyl alcohol (>90%) and brushes for cleaning
* Multimeter for testing
* X-Acto knife blades for heat shielding

== Removal Procedure ==

=== Hot Air Method (Recommended) ===
# Set hot air station to approximately 350-380°C, medium airflow
# Place X-Acto blades or metal shields around the capacitor to protect nearby plastic connectors
# Apply heat evenly around the capacitor until solder melts
# Use tweezers to lift the capacitor from the pads
# Repeat for all SMD capacitors

=== Soldering Iron Method ===
# Apply flux to the capacitor terminals
# Heat one terminal while gently applying pressure to tilt the capacitor
# Alternate between terminals, rocking the capacitor until it releases
# '''Warning:''' This method risks pad lifting if too much force is applied

=== Twist-Off Method (Not Recommended) ===
Some technicians grip the capacitor with pliers and twist to fatigue the terminals. This method:
* Risks lifting pads from the PCB
* May crack the board
* Should only be used on boards that are already damaged

== Cleaning ==

After capacitor removal:
# Inspect pads for damage; repair lifted traces before proceeding
# Clean residue with isopropyl alcohol and a soft brush
# For heavy contamination, scrub with distilled water and dish soap
# Rinse with distilled water, then final rinse with isopropyl alcohol
# Allow to dry completely (24+ hours) before installing new capacitors

If corrosion has damaged traces:
* Use a conductive trace pen for minor repairs
* Solder jumper wires for major trace damage
* Test continuity with a multimeter before reassembly

== Installation ==

=== Polarity ===
'''Critical:''' Electrolytic and tantalum capacitors are polarized. Installing backwards will cause:
* Immediate failure (electrolytics may bulge or pop)
* Short circuit failure (tantalums can burn or catch fire)

The '''negative terminal''' is typically marked on the PCB with:
* A filled-in side of the capacitor symbol
* A stripe or bar on the silkscreen

On electrolytic capacitors, the negative terminal is marked with a stripe.
On tantalum capacitors, the positive terminal is marked (stripe, bar, or "+").

=== Soldering SMD Capacitors ===
# Tin one pad with fresh solder
# Hold the capacitor with tweezers, position on pads
# Tack one terminal by reheating the tinned pad
# Verify alignment, then solder the second terminal
# Reflow the first terminal with additional solder if needed
# Clean flux residue with isopropyl alcohol

=== Soldering Axial Capacitors ===
# Insert leads through holes (or bend for surface mounting if holes are damaged)
# Verify polarity
# Solder both terminals
# Trim excess leads

== Testing ==

Before reassembling the Macintosh IIsi:
# Visual inspection — verify all capacitors are correctly oriented
# Continuity test — check that no solder bridges exist between pads
# Power-on test — with logic board outside case, briefly power on and verify operation
# Extended test — run the system for several hours to verify stability

== Purchasing Kits ==

Pre-made capacitor kits for the Macintosh IIsi are available from:
* Console5 (console5.com)
* ToTsRC/ToTsRETRO (totsrc.com)
* Various eBay sellers

These kits typically include all logic board capacitors and sometimes power supply capacitors as well.

== References ==
<references />

== Related Pages ==
* [[Macintosh IIsi]]
* [[Macintosh IIsi General Maintenance]]
* [[Macintosh IIsi Troubleshooting]]

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

Macintosh IIsi Capacitor Replacement Guide - Revision history

Josh: Added Capacitor_Replacement_Guides category

Josh: Added recap guide image from Recap-a-Mac

Josh: Created Macintosh IIsi Capacitor Replacement Guide