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|
|Macintosh IIsi Logic Board with the caps removed|
Following a precious advice I again learned from Bruce, note on the photo above that I have some exacto knives blades and springs near the board. I used these blades (springs to hold them in place) to shield the heat from the desoldering station from hiting other components nearby, especially plastic connectors that could permanently be deformed due to hot air.
|Close-up look of the IIsi board without the caps|
|Macintosh SE/30 Logic Board with the original caps|
Check this video I made with a digital microscope showing the removal of the old caps, cleaning of the pads and installation of the new capacitors:
|The Macintosh SE/30 Logic Board with the new tantalum caps|
Now, moving on to the power supply:
|Macintosh IIsi Power Supply opened|
|Power Supply board removed from the case|
|Capacitor juice marks everywhere on the board and corrosion present|
|After cleaning the board with distilled water+soap and rinsing with alcohol|
|Installing the new capacitors in the power supply|
|New capacitors installed|
|Power supply assembled|
|Fixing the new caps with hot glue to replicate the original fixture|
|I left a note inside to show to the next technician when it was last recapped :)|
These vintage boards and power supply are now ready for the next 30 years!