There was a peripheral reason I went off on the capacitor voltage rating tangent. An acquaintance mentioned the Tektronix TDS500 - TDS700 series of digital scopes that came out in the '90s. These were a really nice 4 channel, 500 Mhz digital scope which were $$$$. You can now find them for less than $200 on EBay, not because they are out dated; but, because they have a bit of a reputation for croaking. Since I have never set eyes on one, I can't verify; but he claimed that they suffer from the leaky electrolytic problem which was brought on by Tektronix using marginal voltage ratings on the capacitors (strikes me as odd as this would not have been a price point product for Tektronix when it was released). He says that techy people in the know buy these things and do the capacitor replacement with next voltage step up rated caps (switched fro 10 v to 16 v) because new 500 Mhz 4 channel scopes are in the $4000+ range. Apparently Tektronix knew they might have had a problem because they did a lot of switching to tantalum caps on their high end scopes. Again, all anecdotal.
The voltage rating thing got me thinking about the C19 and C25 capacitors on the Bose amplifiers which anecdotally seem to be common failure points. C19 and C25 are on the power supply side and others have pointed out that their 16 v rating might be marginal. Typically the running voltage on a car is around 14- 14.2 volts which gives a 13 % margin with a 16 volt capacitor. If there is any construction uncertainty in the capacitors voltage rating or the capacitors withstand deteriorates as it ages, that margin may disappear. As such, I was thinking that rather than trying for a 16 volt higher temperature / longer life rating it might be useful to try a step up in the voltage rating (next would be 20v or 25v). I recognize that may be a problem because the real estate around those capacitors is limited and higher voltage ratings come with larger size. Higher voltage rating, all things being equal, also usually come with an increase in ESR which may or may not be a problem.
Anyway - just a thought.
The voltage rating thing got me thinking about the C19 and C25 capacitors on the Bose amplifiers which anecdotally seem to be common failure points. C19 and C25 are on the power supply side and others have pointed out that their 16 v rating might be marginal. Typically the running voltage on a car is around 14- 14.2 volts which gives a 13 % margin with a 16 volt capacitor. If there is any construction uncertainty in the capacitors voltage rating or the capacitors withstand deteriorates as it ages, that margin may disappear. As such, I was thinking that rather than trying for a 16 volt higher temperature / longer life rating it might be useful to try a step up in the voltage rating (next would be 20v or 25v). I recognize that may be a problem because the real estate around those capacitors is limited and higher voltage ratings come with larger size. Higher voltage rating, all things being equal, also usually come with an increase in ESR which may or may not be a problem.
Anyway - just a thought.
