Sinclair ZX80 Capacitor Replacement Guide: Difference between revisions
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'''Replacing the electrolytic capacitors (“recapping”) in your Sinclair ZX80 is a crucial preventative maintenance step.''' | '''Replacing the electrolytic capacitors (“recapping”) in your Sinclair ZX80 is a crucial preventative maintenance step.''' | ||
Original capacitors from 1980 are now far beyond their expected lifespan, and failure can cause instability, video issues, or even prevent startup. Fresh, quality capacitors restore reliable operation and protect | Original capacitors from 1980 are now far beyond their expected lifespan, and failure can cause instability, video issues, or even prevent startup. Fresh, quality capacitors restore reliable operation and protect logic chips. | ||
== | == Visual Inspection & Failure Signs == | ||
* '''Leaking or crusty capacitors''' – Look for brown, green, or white residue at the base of any can. | * '''Leaking or crusty capacitors''' – Look for brown, green, or white residue at the base of any can. | ||
* '''Bulging or tilted cans''' – Even small axial capacitors may bulge or lean if failing. | * '''Bulging or tilted cans''' – Even small axial capacitors may bulge or lean if failing. | ||
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If '''any''' capacitor shows trouble, replace '''all''' electrolytics on the board. | If '''any''' capacitor shows trouble, replace '''all''' electrolytics on the board. | ||
== | == Sinclair ZX80 Capacitor List == | ||
The ZX80 uses a small number of electrolytic capacitors, all easily accessible on the main PCB. | The ZX80 uses a small number of electrolytic capacitors, all easily accessible on the main PCB. | ||
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''All original capacitors are axial-lead types. Modern radial types may be used if carefully fitted and insulated.'' | ''All original capacitors are axial-lead types. Modern radial types may be used if carefully fitted and insulated.'' | ||
== | == ZX80 Recapping Procedure == | ||
# '''Unplug and disassemble''' – Remove the case screws and carefully lift the top shell. | # '''Unplug and disassemble''' – Remove the case screws and carefully lift the top shell. | ||
# '''Remove the PCB''' – Disconnect the keyboard membrane and gently free the main board. | # '''Remove the PCB''' – Disconnect the keyboard membrane and gently free the main board. | ||
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# '''Reassemble and test''' – Power up and confirm stable video and reliable boot. | # '''Reassemble and test''' – Power up and confirm stable video and reliable boot. | ||
== | == Post-Recap Voltage Checks == | ||
After recapping, measure the +5V rail at the 7805 regulator output and at the RAM/CPU pins: | After recapping, measure the +5V rail at the 7805 regulator output and at the RAM/CPU pins: | ||
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''Excessive ripple or voltage drop may indicate a faulty regulator or incorrect capacitor installation.'' | ''Excessive ripple or voltage drop may indicate a faulty regulator or incorrect capacitor installation.'' | ||
== | == Recommended Tools & Parts == | ||
* Temperature-controlled soldering iron (fine tip, 1–2 mm) | * Temperature-controlled soldering iron (fine tip, 1–2 mm) | ||
* Desoldering braid and/or pump | * Desoldering braid and/or pump | ||
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* Heatshrink tubing (for radial cap lead insulation) | * Heatshrink tubing (for radial cap lead insulation) | ||
== | == Extra Tips == | ||
* '''Double-check polarity!''' The ZX80 board is single-sided and traces lift easily. | * '''Double-check polarity!''' The ZX80 board is single-sided and traces lift easily. | ||
* '''Use axial capacitors''' for easiest fit, but radial types are fine if insulated and laid flat. | * '''Use axial capacitors''' for easiest fit, but radial types are fine if insulated and laid flat. | ||
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* '''Store the ZX80 in a dry place''' – moisture accelerates capacitor aging. | * '''Store the ZX80 in a dry place''' – moisture accelerates capacitor aging. | ||
== | == Related Pages == | ||
* [[Sinclair ZX80 Troubleshooting Guide]] | * [[Sinclair ZX80 Troubleshooting Guide]] | ||
* [[Sinclair ZX81 Capacitor Replacement Guide]] | * [[Sinclair ZX81 Capacitor Replacement Guide]] | ||
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[[Category:Sinclair Computers]] | [[Category:Sinclair Computers]] | ||
[[Category:Capacitor Replacement Guides]] | [[Category:Capacitor Replacement Guides]] | ||