Jump to content

Acorn Archimedes A3000 Capacitor Guide: Difference between revisions

From RetroTechCollection
← Older edit

Josh (talk | contribs)

5 user groups
12,555 edits
undo
VisualWikitext
Remove emoji from section headings; de-duplicate ref definitions that produced visible cite errors; merge the duplicated References section; targeted corrections noted in the drive report
Rebuild capacitor list from Service Manual pp. 52-54: add missing C93-C112 (four electrolytics, two axials, four tantalums), upgrade boards, part numbers; correct C74; add Acorn's fault-procedure capacitors; drop uncited PSU recap and RIFA advice
 
Line 1: Line 1:
<templatestyles src="Template:StyledTable/styles.css" />
<templatestyles src="Template:StyledTable/styles.css" />
[[File:Acorn Archimedes A3000 motherboard.jpg|thumb|360x360px|Acorn A3000 main PCB. The board electrolytics are leaded radial/axial cans; the small surface-mount parts are ceramic decouplers, not electrolytics.]]
[[File:Acorn Archimedes A3000 motherboard.jpg|thumb|360x360px|A3000 main board 0180,000 Issue 3. The radial electrolytics are the blue cans; B1, the backup cell, is at the bottom left.]]


This guide lists the capacitors on the '''[[Acorn Archimedes A3000]]''' main PCB and covers the recap. The values, designators and Acorn part numbers come directly from the [[Acorn A3000 Service Manual]] PCB assembly parts list.<ref name="sm">[[Acorn A3000 Service Manual]], Acorn Computers &mdash; hosted on this wiki. PCB assembly parts list: capacitor designators C1&ndash;C91, values, types ("ALEC" aluminium electrolytic, "TANT" tantalum, "DCPLR" SMD ceramic decoupler, "CPLT" plate ceramic) and Acorn part numbers; also the PSU output spec and mains-hazard warning.</ref>
The [[Acorn Archimedes A3000]] main board uses leaded radial and axial aluminium electrolytics and leaded tantalums, with surface-mount ceramic decouplers. Every capacitor on the board, and on Acorn's two internal upgrades, is listed with its value, voltage, type and Acorn part number in the parts lists of the [[Acorn A3000 Service Manual]].<ref name="sm-parts">Acorn Computers, ''A3000 Service Manual'', part 0480,050, issue 1, September 1989, pp. 52-54 (main PCB assembly parts list, 2 MB RAM upgrade and User Port/MIDI upgrade). Hosted on this wiki as [[Acorn A3000 Service Manual]].</ref> The tables below are taken from those lists. The leaking backup cell, B1, does more damage to these boards than the capacitors do; deal with it first (see the [[Acorn Archimedes A3000 Maintenance Guide]]).


== Safety ==
== Safety ==


The A3000 contains a mains-powered switch-mode PSU. '''Disconnect the mains lead before opening the case.''' Board-level capacitor work is low voltage once the supply is disconnected, but the PSU module itself carries mains-side capacitors that can hold charge &mdash; treat the PSU module with the same caution as any mains switch-mode supply (see the PSU section below).
Warning: the power supply inside the case runs from the mains. Acorn's service manual warns that dangerous voltages are exposed when the cover is removed and that the computer must be disconnected from the mains first.<ref name="sm-exp">Acorn Computers, ''A3000 Service Manual'', part 0480,050, issue 1, September 1989, p. 25 (danger notice). Hosted on this wiki as [[Acorn A3000 Service Manual]].</ref> Capacitors on the primary side of the supply can hold a charge after the plug is pulled. Discharge them and confirm with a meter before touching that side.


== Is the A3000 a recap candidate? ==
The main board is a four-layer PCB, and Acorn says components should be removed from it only with equipment designed for the job.<ref name="sm-fault">Acorn Computers, ''A3000 Service Manual'', part 0480,050, issue 1, September 1989, pp. 45-50 (main PCB fault diagnosis and repair). Hosted on this wiki as [[Acorn A3000 Service Manual]].</ref> A through-hole pad pulled from an inner-layer connection is hard to repair, so use a desoldering station or plenty of fresh solder and wick, and do not pull a lead until the joint is fully molten.


The A3000 board uses '''leaded aluminium electrolytics and tantalums''', not the leaking surface-mount electrolytics of the later [[Acorn Archimedes A5000]], A4 laptop and Risc PC. The board therefore ages gently; the urgent items on an A3000 are the '''CMOS backup battery''' (which leaks and corrodes the bottom-left corner &mdash; see [[Acorn Archimedes A3000 Maintenance Guide]]) and the '''PSU module'''. A board recap is still reasonable on a 35-year-old machine that is already open, or to chase ripple-related instability.
== Failure signs ==


== Visual inspection ==
* An electrolytic with a domed top, a vented seal, residue around the base or a cracked sleeve.
* A tantalum that has gone short circuit. Acorn's video fault procedure checks C100 for a short when L18 is open, and its audio procedure checks C108 when L19 is open.<ref name="sm-fault" />
* Printer faults. Acorn notes that C23-C33 on the printer port occasionally go open circuit.<ref name="sm-fault" />


Check each electrolytic for a bulged or vented top, leaked electrolyte, a cracked sleeve, or a tired joint. The radial electrolytics cluster around the supply and audio sections; the two axial parts (C39, C83) are 47&nbsp;µF/10&nbsp;V.
See [[Capacitor Failure Symptoms]] for general signs.


== Acorn A3000 capacitor list (electrolytic and tantalum) ==
== A3000 capacitor list ==


These are the recap targets &mdash; the ceramic decouplers (33&nbsp;nF/100&nbsp;nF SMD) and plate ceramics are stable and are left in place.
=== Electrolytic and tantalum capacitors, main PCB ===


<templatestyles src="Template:StyledTable/styles.css" />
{| class="wikitable styled-table" style="width:100%; text-align:center;"
{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''A3000 main PCB &mdash; aluminium electrolytic capacitors'''
|+'''A3000 main PCB electrolytic and tantalum capacitors (Service Manual pp. 52-53)'''
! Designator !! Value !! Voltage !! Mounting
! Designator !! Value !! Voltage !! Type !! Acorn part no.
|-
|-
| C6, C7, C8, C9, C10 || 10&nbsp;µF || 16&nbsp;V || Radial
| C4, C13, C22, C34, C55, C57, C78, C89, C94, C100, C108, C111 || 10 µF || 10 V || Tantalum || 0610,010
|-
|-
| C19 || 10&nbsp;µF || 16&nbsp;V || Radial
| C6, C7, C8, C9, C10, C19, C93, C97 || 10 µF || 16 V || Aluminium electrolytic, radial || 0635,100
|-
|-
| C67 || 4.7&nbsp;µF || 16&nbsp;V || Radial
| C12, C14, C61, C66, C69, C112 || 220 µF || 16 V || Aluminium electrolytic, radial || 0635,230
|-
|-
| C15, C60, C63 || 47&nbsp;µF || 16&nbsp;V || Radial
| C15, C60, C63, C95 || 47 µF || 16 V || Aluminium electrolytic, radial || 0635,470
|-
|-
| C39, C83 || 47&nbsp;µF || 10&nbsp;V || Axial
| C39, C83, C109, C110 || 47 µF || 10 V || Aluminium electrolytic, axial || 0621,470
|-
|-
| C65, C70 || 100&nbsp;µF || 25&nbsp;V || Radial
| C65, C70 || 100 µF || 25 V || Aluminium electrolytic, radial || 0642,103
|-
|-
| C12, C14, C61, C66, C69 || 220&nbsp;µF || 16&nbsp;V || Radial
| C67 || 4.7 µF || 16 V || Aluminium electrolytic, radial || 0635,047
|}
|}


<templatestyles src="Template:StyledTable/styles.css" />
That is 25 aluminium electrolytics and 12 tantalums. Acorn numbers capacitors in a single sequence across all types, so the electrolytics are scattered through C1-C116 among the ceramics.<ref name="sm-parts" />
{| class="wikitable styled-table" style="width:100%; text-align:center;"
 
|+'''A3000 main PCB &mdash; tantalum capacitors'''
=== Upgrade boards ===
! Designator !! Value !! Voltage
 
{| class="wikitable styled-table" style="width:80%; text-align:center;"
|+'''Electrolytics on Acorn's internal upgrades (Service Manual p. 54)'''
! Board !! Designator !! Value !! Voltage !! Acorn part no.
|-
| 2 MB RAM upgrade || C9, C10 || 47 µF || 16 V || 0635,470
|-
|-
| C4, C13, C22, C34, C55, C57, C78, C89 || 10&nbsp;µF || 10&nbsp;V
| User Port/MIDI upgrade || C1 || 220 µF || 16 V || 0635,230
|}
|}


The remaining board capacitors are ceramic and not normally replaced: 33&nbsp;nF and 100&nbsp;nF surface-mount decouplers (the "DCPLR 1210" parts, e.g. C1, C5, C11, C17, C18, C20, C21, C35&ndash;C37, C40&ndash;C54, C56, C58, C59, C64, C71&ndash;C74, C76, C84, C87) and plate ceramics (33&nbsp;pF C2, 12&nbsp;pF C16, 100&nbsp;pF C23/C32/C33, 1&nbsp;nF C79/C85, 2.2&nbsp;nF C24&ndash;C31/C75/C81/C82/C86/C90/C91), plus a few 47&nbsp;nF ceramics (C3, C62, C68, C74) and 100&nbsp;nF/22&nbsp;nF polyester (C80/C88, C77).<ref name="sm" />
The RAM upgrade also carries eight 100 nF axial decouplers (C1-C8), and the User Port/MIDI board seven 33/47 nF decouplers (C2-C8).<ref name="sm-parts" />
 
=== Ceramic and film capacitors ===
 
The remaining positions are ceramic or film capacitors. Of these, only C23-C33 and C107 appear in Acorn's fault procedures.<ref name="sm-parts" />
 
* 33 nF surface-mount decouplers (1210): C1, C5, C11, C17, C18, C20, C21, C35-C37, C40-C47, C50-C54, C59, C64, C76, C87, C98, C99, C105, C106, C113, C500-C506.
* 100 nF surface-mount decouplers (1210): C48, C49, C56, C58, C71-C73, C84.
* 47 nF ceramic: C3, C62, C68, C74, C96, C107.
* Plate ceramics: 10 pF C114; 12 pF C16; 33 pF C2, C115; 100 pF C23, C32, C33; 1 nF C79, C85; 2.2 nF C24-C31, C75, C81, C82, C86, C90, C91; 2.7 nF C116.
* Metallised polyester, 50 V: 22 nF C77, C92; 100 nF C80, C88.
* Not fitted: C38, C101-C104.
 
== Capacitors in Acorn's fault procedures ==


== Replacement summary ==
{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''Capacitors named in the A3000 Service Manual fault chapter (pp. 49-50)'''<ref name="sm-fault" />
! Fault !! Acorn's check
|-
| No video || +5 V should be present on both ends of L18. If L18 is open, check C100 for a short and replace L18 and C100 as needed. IC41 (VIDC) pin 43 should be about 3.5 V; if not, check R109, D16 and C93.
|-
| No audio at all || +5 V should be present on both ends of L19. If L19 is open, check C108 before replacing it. VIDC pin 12 should be about 3 V; if not, check R500, C107 and C108.
|-
| Clock and CMOS RAM lose data || With the power off, IC6 pin 8 should read about 1.1 V. Below 1 V, change B1 and check D2 and C15.
|-
| Printer problems || C23-C33 on the printer port occasionally go open circuit.
|}


Use 105&nbsp;°C low-ESR aluminium electrolytics of equal capacitance and equal-or-higher voltage; tantalums may be replaced with tantalum or a good electrolytic of equal value.
== Parts to buy ==


<templatestyles src="Template:StyledTable/styles.css" />
{| class="wikitable styled-table" style="width:80%; text-align:center;"
{| class="wikitable styled-table" style="width:80%; text-align:center;"
|+'''Board recap shopping list'''
|+'''A3000 main PCB electrolytics and tantalums by value'''
! Value !! Voltage !! Type !! Qty
! Value !! Voltage !! Type !! Quantity
|-
|-
| 4.7&nbsp;µF || 16&nbsp;V || Electrolytic (radial) || 1
| 4.7 µF || 16 V || Radial electrolytic || 1
|-
|-
| 10&nbsp;µF || 16&nbsp;V || Electrolytic (radial) || 6
| 10 µF || 16 V || Radial electrolytic || 8
|-
|-
| 10&nbsp;µF || 10&nbsp;V || Tantalum || 8
| 47 µF || 16 V || Radial electrolytic || 4
|-
|-
| 47&nbsp;µF || 16&nbsp;V || Electrolytic (radial) || 3
| 100 µF || 25 V || Radial electrolytic || 2
|-
|-
| 47&nbsp;µF || 10&nbsp;V || Electrolytic (axial) || 2
| 220 µF || 16 V || Radial electrolytic || 6
|-
|-
| 100&nbsp;µF || 25&nbsp;V || Electrolytic (radial) || 2
| 47 µF || 10 V || Axial electrolytic || 4
|-
|-
| 220&nbsp;µF || 16&nbsp;V || Electrolytic (radial) || 5
| 10 µF || 10 V || Tantalum || 12
|}
|}
Add two 47 µF 16 V for the RAM upgrade and one 220 µF 16 V for the User Port/MIDI board if fitted. A replacement can have the same or a higher voltage rating, provided it fits the footprint. For the axial positions, an axial part keeps the original layout.


== Replacement procedure ==
== Replacement procedure ==


# Disconnect the mains lead; open the case and remove the main PCB.
# Disconnect the mains lead. Remove the top cover, keyboard, floppy drive and any RAM upgrade, then the main PCB (Service Manual pp. 31-32).<ref name="sm-dis">Acorn Computers, ''A3000 Service Manual'', part 0480,050, issue 1, September 1989, pp. 31-32 (disassembly and reassembly). Hosted on this wiki as [[Acorn A3000 Service Manual]].</ref>
# Mark the polarity of each electrolytic/tantalum before removal (the silkscreen marks the positive pad).
# Photograph the board and note the polarity mark of every electrolytic and tantalum before removing anything.
# Wet both leads with fresh solder/flux, lift each end in turn, and clear the holes with solder wick.
# Remove B1 at the same time if it is still fitted, and clean any leakage before fitting new parts.
# Fit the new part with correct polarity, solder and trim. Reverse-fitted tantalums fail short, so double-check C4/C13/C22/C34/C55/C57/C78/C89.
# Desolder each part with a desoldering station, or add fresh solder and clear the holes with wick. Do not lever parts out of the four-layer board.
# Inspect for clean joints and no bridges before reassembly.
# Fit the new part with the correct polarity, solder and trim. A reversed tantalum fails short.
 
# Check every joint for bridges before refitting the board.
== PSU module ==


The A3000's switch-mode PSU is a separate cased module containing mains-side suppression capacitors and bulk smoothing electrolytics (output 5&nbsp;V at up to 4.4&nbsp;A, 22&nbsp;W; ripple should be within 50&nbsp;mV pk-pk).<ref name="sm" /> Acorn's service manual treated it as an exchange unit, but replacement modules are long gone, so a supply that shows ripple or causes random resets is '''recapped'''.
== Power supply ==


'''Danger:''' the primary side and the reservoir and mains-suppression capacitors can hold a '''lethal charge after the machine is unplugged''' &mdash; a shock from them can be fatal. Only work on the PSU if you are competent with mains switch-mode supplies. Unplug the mains lead, '''discharge the reservoir capacitor through a bleeder resistor and confirm 0&nbsp;V with a meter''' before touching the primary side, then replace the electrolytics and any cracked mains-suppression (RIFA-style) capacitor &mdash; the suppression parts must be replaced with safety-rated X/Y-class capacitors, never ordinary ones. Read each value off the fitted part, and re-apply the earth-continuity and insulation safety tests afterward.
The supply is part 0180,010, "22W 240V PSU", in the final assembly parts list.<ref name="sm-parts" /> Acorn's service manual covers only removing and refitting it as a unit and gives no component list or circuit for it, so read each value and voltage off the part being replaced.<ref name="sm-dis" /> When refitting, replace the plastic insulating film beneath it and locate its cover correctly.<ref name="sm-dis" />


== Post-recap verification ==
== Checks after recapping ==


# Reassemble; reconnect the mains lead.
# Measure the +5 V rail. Acorn's specification is 4.9-5.1 V, with ripple and noise up to 50 mV peak to peak.<ref name="sm-psu">Acorn Computers, ''A3000 Service Manual'', part 0480,050, issue 1, September 1989, p. 19 (power supply performance). Hosted on this wiki as [[Acorn A3000 Service Manual]].</ref>
# Power on and confirm RISC OS reaches the desktop.
# Check that the machine reaches the desktop, then test sound through the speakers and headphones, a floppy read, and the printer port if it is used.
# Measure the +5&nbsp;V rail (4.9&ndash;5.1&nbsp;V) and check ripple is within 50&nbsp;mV pk-pk.
# Run Acorn's functional tests from the service manual if a test disc is available (pp. 36-43).
# Confirm sound (the A3000 has stereo output) and a floppy access.
# If a function that worked before the recap now fails, check the polarity of the parts in that area first.


If a previously-working function fails after the recap, re-check the polarity of every replaced electrolytic and tantalum first.
After refitting or replacing an assembly, Acorn requires an earth continuity test on the assembled computer, between the mains plug earth pin and the expansion-card fixing screws and printer-port fixing bolts (pp. 33 and 45; Appendix B, p. 57).


== Related pages ==
== Related pages ==
Line 102: Line 132:
* [[Acorn Archimedes A3000 Maintenance Guide]]
* [[Acorn Archimedes A3000 Maintenance Guide]]
* [[Acorn Archimedes A3000 Troubleshooting Guide]]
* [[Acorn Archimedes A3000 Troubleshooting Guide]]
* [[Acorn Archimedes A4000 Capacitor Guide]]
* [[Acorn Archimedes A3010 Capacitor Guide]]
* [[Capacitor Failure Symptoms]]
* [[Capacitor Failure Symptoms]]


Latest revision as of 07:42, 1 October 2026

A3000 main board 0180,000 Issue 3. The radial electrolytics are the blue cans; B1, the backup cell, is at the bottom left.

The Acorn Archimedes A3000 main board uses leaded radial and axial aluminium electrolytics and leaded tantalums, with surface-mount ceramic decouplers. Every capacitor on the board, and on Acorn's two internal upgrades, is listed with its value, voltage, type and Acorn part number in the parts lists of the Acorn A3000 Service Manual.[1] The tables below are taken from those lists. The leaking backup cell, B1, does more damage to these boards than the capacitors do; deal with it first (see the Acorn Archimedes A3000 Maintenance Guide).

Safety

[edit | edit source]

Warning: the power supply inside the case runs from the mains. Acorn's service manual warns that dangerous voltages are exposed when the cover is removed and that the computer must be disconnected from the mains first.[2] Capacitors on the primary side of the supply can hold a charge after the plug is pulled. Discharge them and confirm with a meter before touching that side.

The main board is a four-layer PCB, and Acorn says components should be removed from it only with equipment designed for the job.[3] A through-hole pad pulled from an inner-layer connection is hard to repair, so use a desoldering station or plenty of fresh solder and wick, and do not pull a lead until the joint is fully molten.

Failure signs

[edit | edit source]
  • An electrolytic with a domed top, a vented seal, residue around the base or a cracked sleeve.
  • A tantalum that has gone short circuit. Acorn's video fault procedure checks C100 for a short when L18 is open, and its audio procedure checks C108 when L19 is open.[3]
  • Printer faults. Acorn notes that C23-C33 on the printer port occasionally go open circuit.[3]

See Capacitor Failure Symptoms for general signs.

A3000 capacitor list

[edit | edit source]

Electrolytic and tantalum capacitors, main PCB

[edit | edit source]
A3000 main PCB electrolytic and tantalum capacitors (Service Manual pp. 52-53)
Designator Value Voltage Type Acorn part no.
C4, C13, C22, C34, C55, C57, C78, C89, C94, C100, C108, C111 10 µF 10 V Tantalum 0610,010
C6, C7, C8, C9, C10, C19, C93, C97 10 µF 16 V Aluminium electrolytic, radial 0635,100
C12, C14, C61, C66, C69, C112 220 µF 16 V Aluminium electrolytic, radial 0635,230
C15, C60, C63, C95 47 µF 16 V Aluminium electrolytic, radial 0635,470
C39, C83, C109, C110 47 µF 10 V Aluminium electrolytic, axial 0621,470
C65, C70 100 µF 25 V Aluminium electrolytic, radial 0642,103
C67 4.7 µF 16 V Aluminium electrolytic, radial 0635,047

That is 25 aluminium electrolytics and 12 tantalums. Acorn numbers capacitors in a single sequence across all types, so the electrolytics are scattered through C1-C116 among the ceramics.[1]

Upgrade boards

[edit | edit source]
Electrolytics on Acorn's internal upgrades (Service Manual p. 54)
Board Designator Value Voltage Acorn part no.
2 MB RAM upgrade C9, C10 47 µF 16 V 0635,470
User Port/MIDI upgrade C1 220 µF 16 V 0635,230

The RAM upgrade also carries eight 100 nF axial decouplers (C1-C8), and the User Port/MIDI board seven 33/47 nF decouplers (C2-C8).[1]

Ceramic and film capacitors

[edit | edit source]

The remaining positions are ceramic or film capacitors. Of these, only C23-C33 and C107 appear in Acorn's fault procedures.[1]

  • 33 nF surface-mount decouplers (1210): C1, C5, C11, C17, C18, C20, C21, C35-C37, C40-C47, C50-C54, C59, C64, C76, C87, C98, C99, C105, C106, C113, C500-C506.
  • 100 nF surface-mount decouplers (1210): C48, C49, C56, C58, C71-C73, C84.
  • 47 nF ceramic: C3, C62, C68, C74, C96, C107.
  • Plate ceramics: 10 pF C114; 12 pF C16; 33 pF C2, C115; 100 pF C23, C32, C33; 1 nF C79, C85; 2.2 nF C24-C31, C75, C81, C82, C86, C90, C91; 2.7 nF C116.
  • Metallised polyester, 50 V: 22 nF C77, C92; 100 nF C80, C88.
  • Not fitted: C38, C101-C104.

Capacitors in Acorn's fault procedures

[edit | edit source]
Capacitors named in the A3000 Service Manual fault chapter (pp. 49-50)[3]
Fault Acorn's check
No video +5 V should be present on both ends of L18. If L18 is open, check C100 for a short and replace L18 and C100 as needed. IC41 (VIDC) pin 43 should be about 3.5 V; if not, check R109, D16 and C93.
No audio at all +5 V should be present on both ends of L19. If L19 is open, check C108 before replacing it. VIDC pin 12 should be about 3 V; if not, check R500, C107 and C108.
Clock and CMOS RAM lose data With the power off, IC6 pin 8 should read about 1.1 V. Below 1 V, change B1 and check D2 and C15.
Printer problems C23-C33 on the printer port occasionally go open circuit.

Parts to buy

[edit | edit source]
A3000 main PCB electrolytics and tantalums by value
Value Voltage Type Quantity
4.7 µF 16 V Radial electrolytic 1
10 µF 16 V Radial electrolytic 8
47 µF 16 V Radial electrolytic 4
100 µF 25 V Radial electrolytic 2
220 µF 16 V Radial electrolytic 6
47 µF 10 V Axial electrolytic 4
10 µF 10 V Tantalum 12

Add two 47 µF 16 V for the RAM upgrade and one 220 µF 16 V for the User Port/MIDI board if fitted. A replacement can have the same or a higher voltage rating, provided it fits the footprint. For the axial positions, an axial part keeps the original layout.

Replacement procedure

[edit | edit source]
  1. Disconnect the mains lead. Remove the top cover, keyboard, floppy drive and any RAM upgrade, then the main PCB (Service Manual pp. 31-32).[4]
  2. Photograph the board and note the polarity mark of every electrolytic and tantalum before removing anything.
  3. Remove B1 at the same time if it is still fitted, and clean any leakage before fitting new parts.
  4. Desolder each part with a desoldering station, or add fresh solder and clear the holes with wick. Do not lever parts out of the four-layer board.
  5. Fit the new part with the correct polarity, solder and trim. A reversed tantalum fails short.
  6. Check every joint for bridges before refitting the board.

Power supply

[edit | edit source]

The supply is part 0180,010, "22W 240V PSU", in the final assembly parts list.[1] Acorn's service manual covers only removing and refitting it as a unit and gives no component list or circuit for it, so read each value and voltage off the part being replaced.[4] When refitting, replace the plastic insulating film beneath it and locate its cover correctly.[4]

Checks after recapping

[edit | edit source]
  1. Measure the +5 V rail. Acorn's specification is 4.9-5.1 V, with ripple and noise up to 50 mV peak to peak.[5]
  2. Check that the machine reaches the desktop, then test sound through the speakers and headphones, a floppy read, and the printer port if it is used.
  3. Run Acorn's functional tests from the service manual if a test disc is available (pp. 36-43).
  4. If a function that worked before the recap now fails, check the polarity of the parts in that area first.

After refitting or replacing an assembly, Acorn requires an earth continuity test on the assembled computer, between the mains plug earth pin and the expansion-card fixing screws and printer-port fixing bolts (pp. 33 and 45; Appendix B, p. 57).

[edit | edit source]

References

[edit | edit source]
  1. ↑ 1.0 1.1 1.2 1.3 1.4 Acorn Computers, A3000 Service Manual, part 0480,050, issue 1, September 1989, pp. 52-54 (main PCB assembly parts list, 2 MB RAM upgrade and User Port/MIDI upgrade). Hosted on this wiki as Acorn A3000 Service Manual.
  2. ↑ Acorn Computers, A3000 Service Manual, part 0480,050, issue 1, September 1989, p. 25 (danger notice). Hosted on this wiki as Acorn A3000 Service Manual.
  3. ↑ 3.0 3.1 3.2 3.3 Acorn Computers, A3000 Service Manual, part 0480,050, issue 1, September 1989, pp. 45-50 (main PCB fault diagnosis and repair). Hosted on this wiki as Acorn A3000 Service Manual.
  4. ↑ 4.0 4.1 4.2 Acorn Computers, A3000 Service Manual, part 0480,050, issue 1, September 1989, pp. 31-32 (disassembly and reassembly). Hosted on this wiki as Acorn A3000 Service Manual.
  5. ↑ Acorn Computers, A3000 Service Manual, part 0480,050, issue 1, September 1989, p. 19 (power supply performance). Hosted on this wiki as Acorn A3000 Service Manual.


Retrieved from "https://wiki.retrotechcollection.com/index.php?title=Acorn_Archimedes_A3000_Capacitor_Guide&oldid=17122"