PDP 11 gear finally moved

On Fri, 17 Jul 2015, Todd Killingsworth wrote: No. It is because the typical aluminum electrolytic capacitor at 20-30 years old is simply past its useful service life. At that point they tend to suffer from all sorts of issues and can no longer be considered reliable. That whole "botched industrial espionage" thing is also somewhat of a myth. There have been at least 3 different cases where there have been industry wide problems with aluminum electrolytics. The earliest I tend to see are the first generation SMD aluminum electrolytics from the late 1980s to about 1993. Those have problems with their rubber seals due to the rubber compound breaking down either due to the temperature they were reflow soldered at or because the boards were cleaned with chlorinated solvents. Newer SMD aluminum electrolytics do not have this problem (and capacitor manufacturers explicitly warn against using chlorinated solvents to clean pc boards). The second were those which you are referring to above, aka the "capacitor plague". Those started showing up in the marketplace around about 2000 and were mostly gone by about 2005. The third were the ultra-low ESR types from certain major manufacturers. The most common I dealt with were Nippon Chemicon KZG and KZJ (all of them, replace them wholesale on sight) and a batch of Nichicon HN and HM (only a certain date range were affected). The Nippon parts are of a faulty design (which Nippon never would admit to it, instead they tried to wipe all data about them from their site) while the affected Nichicon HN and HM parts were supposedly just overfilled with electrolyte (according to Nichicon). I don't know how much equipment you service, but equipment made in the 80s pretty much needs replacement aluminum electrolytics today if it has many hours on it and/or it needs to remain reliable. I have a number of early '80s monitors and PSUs currently in my repair queue which only need replacement electrolytic capacitors (distorted picture, excessive ripple, etc).