I digged up some capacitors from amplifier and decided to test them, one of them is said to be 8200 uF, the other 4700 uF.
I measured them with LCR meter and it gives very strange numbers.
If LCR meter tests on frequencies 1-100 kHz the LCR meter reads 0L, if LCR tests on 100-120 Hz then it reads around 3 mF for 8200 uF cap(yes, milliFarad, so more than two times less said capacitance). For 4700uF it reads pretty close on lower frequencies, but on higher it is still OL(starting from 1 kHz). I tested the capactiros for short-circuit - no problem.
LCR meter reads small capacitors without a problem.
What is going on? I've seen this before, but I thought maybe the capacitor is dead, but now it comes again. And again with quite big capacitors. The don't have buldges and have no damage.
I usually don't use such big capacitors, so maybe I measure them in wrong way, but I don't have any kind of special mode on LCR meter for big capacitors.
Caps are electrolytes of course.
So the main questions:
Why LCR can't read anything on frequencies higher than 1 kHz for big caps(more LCR meter related quesiton).
*SOLVED - Is it possible for cap to drop it's capacitance to more than two times less? I usually seen capacitance drops for 20-30% for very old caps.
---I found out it is most probably broken capacitor, because other caps I have seem to be within reasonable decrease range.