Editing IBM PS/2 Model 70 (section)

== SMD Electrolyte Leakage — The Famous PS/2 Plague ==

The Model 70 (and the Model 80) planar uses '''surface-mount aluminium electrolytic capacitors''' (SMD electrolytics) — typically 10 µF / 16 V or 47 µF / 16 V — scattered across both sides of the planar for IC supply rail bypassing. The aluminium electrolyte inside these caps is corrosive and the rubber bung seal degrades over decades, allowing the electrolyte to leak onto the planar.

Symptoms of SMD electrolyte leakage:

* Brown / green residue near a SMD cap base.
* Crusty deposits on nearby PCB traces.
* Intermittent POST faults; system passes POST cold but fails when warm.
* Random reboots.
* Specific functional area (e.g., onboard VGA, RTC, serial port) becomes intermittent before failing.
* Eventually, planar dies completely.

The leak is cumulative. Once electrolyte is on the planar surface, it continues to corrode traces and ICs even after the PSU is unplugged. Restoration requires complete SMD cap removal, planar wash (IPA or laboratory cleaning), trace repair where necessary, and recap with modern equivalents.

The Model 70 SMD leak is the single most common cause of an apparently-dead 8570. See [[IBM PS/2 Model 70 Capacitor Replacement Guide]] for the full recap procedure.