07-09-2016, 07:55 AM
I have also used them for timing and they are definitely fine.
The main problem with failing tants on decoupler duty is that they fail short-circuit, not open. that means they often also take out associated pass transistors, fuses etc. Electrolytics seem to go high ESR rather than short, so just become ineffective.
Although I must say I had to take out a big 4700uF/70V cap the other day in a signal generator power supply that had turned itself into a 4 ohm resistor with similar consequences.
The main failure on tiny SMD (surface mount) electrolytics nowadays, especially those from the 80s is that they start to leak, and the leakage can destroy or badly contaminate all the nearby pcb traces. So you just can't win!
The main problem with failing tants on decoupler duty is that they fail short-circuit, not open. that means they often also take out associated pass transistors, fuses etc. Electrolytics seem to go high ESR rather than short, so just become ineffective.
Although I must say I had to take out a big 4700uF/70V cap the other day in a signal generator power supply that had turned itself into a 4 ohm resistor with similar consequences.
The main failure on tiny SMD (surface mount) electrolytics nowadays, especially those from the 80s is that they start to leak, and the leakage can destroy or badly contaminate all the nearby pcb traces. So you just can't win!
Jeremy. G8MLK. BVWS Chairman. British Vintage Wireless and TV Museum Friend.
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