Editing Sinclair ZX Spectrum 128 Capacitor Replacement Guide (section)

== Is the 128 a recap candidate? ==

The 128 uses ordinary leaded electrolytics and is '''not''' a machine with a systematic capacitor plague — it is not a "recap on sight" case. There are, however, only '''13 electrolytics''' on the whole main board, so a targeted recap is quick and cheap when it is justified.

Recap when there is evidence:

* '''Visibly failed parts''' — bulging, leaking, crusty residue or a cracked sleeve.
* '''Supply instability''' — random crashes, or rails out of tolerance or showing ripple. The parts to look at are C25, C44/C45 (supply smoothing) and C111/C112 (the −12 V charge pump).
* '''Dead RS-232 or keypad''' — check C111/C112 in the −12 V charge pump, since both ports depend on that rail.<ref name="sm128" />
* '''Wavy lines across the display''' — press each electrolytic in turn; if the artefact clears while pressing one, that is the culprit.<ref name="ian" />

'''Do not recap to cure jailbars.''' Vertical banding on the RGB output is a noise artefact that survives a routine recap; it has its own specific modification, described below.