Hello all,
I have an old compaq portable I in my possession with a dead power supply, it's is the same power supply that Dave filmed in his video on his YT channel. Visual inspection revealed two blown tantalum 2.2uF 25V caps (C37, C39) close to the comparator circuit, no other caps are bulged but given their age I'm willing to replace them.
I took some of the bigger caps out of circuit to test them and found these values with my DER DE-5000 LCR meter:
3300uF 6.3V reading 3.3mF 0.0ohm ESR @100Hz freq
100uF 250V reading 91.3uF 0.4ohm ESR @100Hz freq
470uF 25V reading 470uF 0.03ohm ESR @1KHz freq
The ESR values above are way off any of the ESR charts I was able to find online (guess it has to do with being older tech, maybe my LCR meter is not sensitive enough) and capacitance values look good to me.
What's the best approach in this case since ESR is undetermined? Should I be replacing them or wasting my money?
I don't understand how a cap can have 0.0ohm ESR, maybe shorted but then how am I reading correct capacitance? Could it be faulty LCR meter?