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Macintosh Classic Capacitor Replacement Guide: Difference between revisions

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Removed unsourced rail tolerance figures and the R56 trimmer adjustment: Apple's Classic/Classic II Service Source publishes neither. Added Apple's Electrical spec and a sourced +-5% logic-supply check
Rewrite. The single undifferentiated capacitor table gave CP1 and CP13 both as 220 uF 250 V with no mention of board variants - but Apple own parts list gives four power/sweep boards, 661-0597 and 661-0651 at 110 V and 661-0599 and 661-0652 at 220 V, and on a 220-240 V board CP1 is a single 220 uF 400 V part with CP13 fitted as a jumper. 240 V mains rectifies to about 340 V, so a 250 V part there fails. The shared power/sweep board now points at the Classic II guide which carries both variant...
 
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Replacing electrolytic capacitors (recapping) in your '''Macintosh Classic''' is essential for restoring power stability, ensuring clean video output, and preventing long-term damage due to capacitor leakage. This guide outlines the recommended procedure and provides complete analog and logic board capacitor specifications.
<templatestyles src="Template:StyledTable/styles.css" />
This guide covers capacitor replacement on the '''[[Macintosh Classic]]''' &mdash; the logic board, which is specific to this machine, and the power/sweep board, which is '''shared with the [[Macintosh Classic II]]''' and is documented in full on that machine's page.
 
{{Warning|'''Apple built this power/sweep board in two mains variants, and one capacitor is rated differently between them.'''
 
Apple's own parts list gives '''four''' field-replaceable power/sweep boards: '''661-0597''' (110 V, Rev. A), '''661-0599''' (220 V, Rev. A), '''661-0651''' (110 V, Rev. B) and '''661-0652''' (220 V, Rev. B).<ref name="APPLESS" />
 
* On a '''110/120 V''' board the mains input is a '''voltage doubler''', and CP1 and CP13 are a series pair of '''220 µF 250 V''' capacitors.
* On a '''220&ndash;240 V''' board there is '''no doubler'''. '''CP1 is a single 220 µF 400 V capacitor, and CP13 is a jumper with no capacitor fitted at all.'''<ref name="c5560" /><ref name="recapanalog" />
 
'''240 V mains rectifies to roughly 340 V DC.''' A 250 V capacitor at CP1 on a 240 V board is far over its rating and will fail &mdash; loudly, and possibly violently.
 
An earlier version of this page gave '''one undifferentiated list''' with CP1 and CP13 both at 220 µF 250 V and no mention of board variants. '''Identify which board you have from its part number before ordering anything.'''}}
 
== Before you start ==


== Capacitor Inspection ==
'''Take the battery out first.''' The 1/2 AA cell in this family leaks and the electrolyte destroys traces, in some cases beyond repair.<ref name="recapclassic" /> See [[Battery Explosion, Capacitor or Corrosion Damage]].


Before recapping, visually inspect all capacitors for common signs of failure:
Then follow the [[CRT Discharge Procedure]]. The power/sweep board carries mains on its primary side and the tube holds charge after the machine is unplugged.


* '''Bulging Tops''' – Swollen or domed caps indicate internal gas buildup.
== Capacitor inspection ==
* '''Electrolyte Leakage''' – Brown/white crust or residue near leads shows capacitor failure.
* '''Corroded Pads or Traces''' – PCB staining or corrosion suggests leakage damage.


If any of these symptoms are present, immediate replacement is advised.
The surface-mount electrolytics on the logic board rarely bulge. Look instead for:


== Macintosh Classic Capacitor List ==
* Dark haloes or dried crust at the base of the cans.
* Dull or green solder joints on nearby IC pins.
* Thinned or missing traces, best seen under a loupe with light raking across the board.


=== Analog Board Capacitors ===
Through-hole electrolytics on the power/sweep board do show the classic symptoms &mdash; domed tops, brown or white crust at the leads, staining on the board beneath them.


The Macintosh Classic analog board has several capacitors that may require replacement. Due to variations in board revisions, consult the specific schematic for your model. Common capacitor values include:
See [[Capacitor Failure Symptoms]].


<templatestyles src="Template:StyledTable/styles.css" />
== Logic board ==
{| class="wikitable styled-table" style="width:100%; text-align:center;"
 
|+ '''Macintosh Classic Analog Board Capacitor Specifications'''
{| class="wikitable styled-table" style="width:70%; text-align:center;"
|-
|+ '''Macintosh Classic logic board'''
! Label !! Capacitance !! Voltage !! Quantity
|-
| CF3 || 1000µF || 16V || 1x
|-
| CF4 || 470µF || 25V || 1x
|-
| CL1 || 1000µF || 25V || 1x
|-
| CL2 || 4.7µF || 250V || 1x
|-
| CL3 || 1µF || 50V || 1x
|-
| CP1 || 220µF || 250V || 1x
|-
| CP10 || 470µF || 25V || 1x
|-
| CP11 || 220µF || 50V || 1x
|-
| CP12 || 1000µF || 16V || 1x
|-
| CP13 || 220µF || 250V || 1x
|-
| CP2 || 470µF || 50V || 1x
|-
| CP34 || 1µF || 50V || 1x
|-
|-
| CP36 || 2200µF || 10V || 1x
! Reference !! Capacitance !! Voltage !! Quantity
|-
|-
| CP4 || 47µF || 25V || 1x
| C1 &ndash; C7 || 47 µF || 16 V || 7
|-
|-
| CP5 || 1µF || 50V || 1x
| C8 || 1 µF || 50 V || 1
|-
| CP6 || 2200µF || 10V || 1x
|-
| CP7 || 1000µF || 10V || 1x
|-
| CP8 || 2200µF || 16V || 1x
|-
| CP9 || 470µF || 25V || 1x
|-
| CV2 || 470µF || 10V || 1x
|-
| CP3 || 10µF || 25V || 1x
|-
| CP37 || 1µF || 50V || 1x
|-
| CL11 || 47µF || 16V || 1x
|-
| CF2 || 220µF || 16V || 1x
|-
| CF1 || 47µF || 25V || 1x
|}
|}


*Note: Capacitor labels and values may vary between board revisions. Always verify with your specific board.*
Eight capacitors in total. From Recap-a-Mac's photographic guide, made from a physical board.<ref name="recapclassic" />
[[File:Mac classic analog recap.jpg|thumb|694x694px|Macintosh Classic Analog Board (INT) Recap Diagram <ref>https://recapamac.com.au/macintosh-classic-analog/</ref>|center]]
 
'''Note that this is not the Classic II's list.''' The [[Macintosh Classic II]] logic board is a different design with either 13 or 17 surface-mount electrolytics depending on revision; do not order a Classic II kit for a Classic.
 
[[File:Mac classic recap.jpg|thumb|600px|center|Macintosh Classic logic board recapping guide. (Image: Recap-a-Mac)]]


=== Logic Board Capacitors ===
=== Replacement parts ===


The Macintosh Classic logic board contains surface-mount electrolytic capacitors prone to leakage and corrosion.
Recap-a-Mac uses solid tantalum at the same values on this board:<ref name="recapclassic" />


<templatestyles src="Template:StyledTable/styles.css" />
* '''1 µF 50 V''' &mdash; KEMET T491B105K050AT
{| class="wikitable styled-table" style="width:100%; text-align:center;"
* '''47 µF 16 V''' &mdash; KEMET T491D476K016AT
|+ '''Macintosh Classic Logic Board Capacitor Specifications'''
 
|-
Solid tantalum has no liquid electrolyte and cannot leak, which is the failure mode that does the damage here. It fails '''short''' rather than open, so derate generously: a part rated well above the rail it sits on is far less likely to be pushed into failure by a switch-on surge. A 25 V part in the 47 µF positions is a common and sensible choice on a 5 V rail.
! Label !! Capacitance !! Voltage !! Quantity
 
|-
== Power/sweep board ==
| C1 – C7 || 47µF || 16V || 7x
|-
| C8 || 1µF || 50V || 1x
|}


''Note: When replacing with tantalum capacitors, consider using 25V rated caps for the 47µF positions to ensure longevity.''
'''This board is shared with the [[Macintosh Classic II]]''', and the full treatment &mdash; separate 120 V and 240 V capacitor lists, the board part numbers 630-0395, 630-0420, 630-0525 and 630-0560, the differences between Console5's and Recap-a-Mac's counts, the PP1 output adjustment, and the DIP ICs IF1, QP1 and JP1 that also fail on these boards &mdash; is on the '''[[Macintosh Classic II Capacitor Replacement Guide#Power/Sweep Board|Classic II capacitor guide]]'''. It is not duplicated here, because a second copy of a safety-critical table is a second copy to get out of step.
[[File:Mac classic recap.jpg|thumb|691x691px|Macintosh Classic Recap Diagram <ref>https://recapamac.com.au/macintosh-classic/</ref>|center]]


== Capacitor Replacement Procedure ==
What you need to know before you go there:


# '''Discharge the CRT''' – Follow standard CRT discharge procedures before working inside.
* '''Read the part number off your board.''' 661-0597 and 661-0651 are the 110 V boards; 661-0599 and 661-0652 are the 220 V boards.<ref name="APPLESS" />
# '''Remove the Logic & Analog Boards''' – Label cables and safely extract both boards.
* '''If CP13 is a jumper rather than a capacitor, you have a 220&ndash;240 V board''', and CP1 must be a '''400 V''' part.
# '''Desolder Old Capacitors''' – Use a quality soldering iron, braid, or pump to remove components cleanly.
* Apple's Service Source '''Electrical''' specification lists only '''100&ndash;120 V AC, 47&ndash;63 Hz, 100 W maximum''' &mdash; it documents the US machine. The parts list in the same document is what reveals that a 220 V board exists.<ref name="APPLESS" />
# '''Clean the Board''' – Thoroughly clean any electrolyte residue with isopropyl alcohol.
# '''Install New Capacitors''' – Insert with correct polarity (check for stripe on negative side).
# '''Solder Carefully''' – Ensure clean, shiny joints without cold solder bridges.
# '''Trim Leads & Inspect Work''' – Cut excess and examine under light or magnification.
# '''Test for Shorts''' – Use a multimeter to confirm there are no shorts across power rails.


== Recommended Tools ==
== Replacement procedure ==


* Temperature-controlled soldering iron (fine tip)
# '''Remove the battery.'''
* Desoldering braid or vacuum pump
# '''Discharge the CRT''' &mdash; see [[CRT Discharge Procedure]].
* Quality leaded solder (0.5 mm recommended)
# Label every cable, then remove the logic board and, if you are working on it, the power/sweep board.
* Isopropyl alcohol and ESD brush
# Desolder the old capacitors. On the logic board use hot air or a low-temperature technique; the pads lift easily on a board that has already been attacked by electrolyte.
* Multimeter
# '''Clean the board.''' Isopropyl alcohol and a soft brush, then inspect under magnification for thinned or broken traces near every capacitor position. Repair those before fitting anything new.
* Safety goggles and insulated gloves
# Fit the replacements with the correct polarity. Check twice on tantalum &mdash; a reversed tantalum fails short and takes the rail down with it.
# Inspect the joints under magnification, trim the leads, and check for shorts across every rail with a meter before applying power.


== Voltage Check After Recap ==
== After the recap ==


'''Apple publishes no rail voltages or tolerances for this machine, and no power-supply adjustment procedure.''' The ''Macintosh Classic / Classic II / Performa 200 Service Source'' hosted on this wiki gives only the mains side in its Electrical specification — line voltage 100–120 V AC, 47–63 Hz single phase, 100 W maximum — and its Adjustments chapter covers video only: light meter setup, cutoff, brightness and contrast, centring, size and focus.
'''Apple publishes no rail voltages or tolerances for this machine, and no power-supply adjustment procedure.''' The ''Macintosh Classic / Classic II / Performa 200 Service Source'' hosted on this wiki gives only the mains side in its Electrical specification, and its Adjustments chapter covers '''video and yoke only''' &mdash; light meter setup, cutoff, brightness and contrast, centring, size and focus.<ref name="APPLESS" />


What you can check is that the rails are inside the range the logic on the board is specified for. 5 V logic is specified for a 5 V supply at ±5 per cent, which gives '''4.75 V to 5.25 V'''; treat anything outside that as a fault, and anything that sags under load or carries visible ripple as a fault regardless of what the DC reading says. Compare against a known-good example of the same model where you can.
What you can check is that the rails sit inside the range the logic on the board is specified for. Five-volt logic is specified for a 5 V supply at &plusmn;5 per cent, which gives '''4.75 V to 5.25 V'''. Treat anything outside that as a fault, and anything that sags under load or carries visible ripple as a fault regardless of what the DC reading says. Compare against a known-good example of the same model where you can.


Measure at the floppy drive or logic board power connector.
Measure at the floppy drive or logic board power connector.


== Tips for Best Results ==
Recap-a-Mac reports that the output voltage on this board can be adjusted with the variable resistor '''PP1''', which is not something Apple documents.<ref name="recapanalog" />


* Always recap the logic board first – leaking caps often cause corrosion damage.
== What not to do ==
* Use quality capacitors (e.g., Nichicon, Panasonic, Rubycon).
 
* Turn on the system periodically to prolong capacitor lifespan.
* '''Do not "power the machine up periodically to keep the capacitors healthy".''' That advice circulates widely and it is the wrong way round for this machine: powering up a Classic with leaking surface-mount electrolytics drives electrolyte further into the board and turns a recap into a trace-repair job. Recap it, '''then''' use it. Regular use after that is fine.
* Replace in full sets for even aging and reliability.
* '''Do not fit a 250 V part at CP1 without confirming you have a 110 V board.''' See the warning at the top.
* Clean the board thoroughly with isopropyl alcohol after removal.
* '''Do not increase capacitance''' because bigger sounds better. On the power/sweep board it changes the inrush the rectifier sees.
 
== Recommended tools ==
 
* Temperature-controlled soldering iron with a fine tip; hot air is easier on the logic board.
* Desoldering braid and a pump.
* Leaded solder, 0.5 mm.
* Isopropyl alcohol, a soft brush and a loupe.
* Multimeter.
* A CRT discharge tool &mdash; see [[Recommended Tools]].


== Related Pages ==
== Related Pages ==
* [[Macintosh Classic / Classic II General Maintenance]]
 
* [[Macintosh Classic / Classic II Troubleshooting]]
* [[Macintosh Classic]] &middot; [[Macintosh Classic / Classic II General Maintenance]] &middot; [[Macintosh Classic / Classic II Troubleshooting]]
* [[Macintosh Floppy Drive Maintenance]]
* [[Macintosh Classic II Capacitor Replacement Guide]] &mdash; the shared power/sweep board, with both mains variants
* [[CRT Discharge Procedure]]
* [[Macintosh Floppy Drive Maintenance]] &middot; [[CRT Discharge Procedure]] &middot; [[Capacitor Failure Symptoms]] &middot; [[Battery Explosion, Capacitor or Corrosion Damage]]
 
== References ==
 
<references>
<ref name="APPLESS">Apple Computer, ''Macintosh Classic / Classic II / Performa 200 Service Source'', hosted on this wiki as [[:File:Macintosh Classic - Classic II.pdf]]. Specifications (Electrical: 100&ndash;120 V AC, 47&ndash;63 Hz single phase, 100 W maximum); Adjustments (Video and Yoke only &mdash; there is no voltage adjustment procedure); and the Exploded View parts list, which gives the power/sweep board as 661-0597 (110 V Rev. A), 661-0599 (220 V Rev. A), 661-0651 (110 V Rev. B) and 661-0652 (220 V Rev. B). Apple's Service Source is module-level throughout: procedures, thresholds and field-replaceable-unit numbers, never component values.</ref>
<ref name="c5560">Console5 TechWiki, "Mac Analog Board: 630-0560" &mdash; [https://wiki.console5.com/wiki/Mac_Analog_Board:_630-0560 wiki.console5.com]. Publishes separate 120 V and 240 V lists for this board, including CP1 at 250 V versus '''400 V''' and CP13 as a jumper on the 240 V board. Secondary source: a vendor capacitor-kit list compiled from physical boards, not Apple documentation.</ref>
<ref name="recapanalog">Bruce / Recap-a-Mac, "Macintosh Classic I + II Analog Board (220V &ndash; 240V version)" &mdash; [https://recapamac.com.au/macintosh-classic-analog/ recapamac.com.au]. Independently photographed from a 240 V board: one 220 µF '''400 V''' part and no 250 V electrolytic anywhere on the board; the PP1 output adjustment; and the IF1, QP1 and JP1 DIP IC failures. Secondary source.</ref>
<ref name="recapclassic">Bruce / Recap-a-Mac, "Macintosh Classic" &mdash; [https://recapamac.com.au/macintosh-classic/ recapamac.com.au]. The logic board capacitor list photographed from a physical board, the 1/2 AA battery failure mode, and the KEMET tantalum part numbers. Secondary source.</ref>
</references>


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