Many vintage (15+ years) electronic boards (PCBs) are at a higher risk of having its non-solid electrolytic capacitors leaking by now. Such leaking occurs regardless of whether the component is actually being used/energized (although storage conditions may further contribute to the component degradation). The leakage happens due to natural aging of the component sealing and/or internal corrosion within the capacitor. The consequence of such leakages can be catastrophic not only for the capacitor itself, but for the electronic board as a whole. Here is why...
The most commonly used capacitor (aka caps) in computer logic boards and power supplies are the non-solid electrolytic capacitors, which use a liquid or gel as electrolyte. The problem is that the electrolyte liquid/gel used in these caps are conductive and corrosive and both these characteristics do not go well if spilled over your PCB. Therefore, when these capacitors leak, they can cause:
1) The PCB to malfunction by creating electric contact (short circuits) between components that were intended to be connected. Depending on the short circuits created by the conductive liquid, it could completely burn components and even create holes in the PCB, potentially damaging the board beyond repair.
2) In addition to shortening components, the corrosive nature of the electrolyte will (with time) corrode the copper traces on the PCB as well as the components terminals to a certain extent. The electrolyte will also cover the solder joints creating a crusty layer that shields the solder joint from heat, requiring you to add more heat to be able to remove components (by desoldering).
|Macintosh IIsi Power Supply with leaky capacitors