Testing for cap leakage at rated voltage question.

[dragonbat13]

I have this Sprague to-6a cap tester I got free.

It will power up to the rated voltage at the banana jacks with a cap installed but I'm having a difficult time getting any trustworthy readings out of the meter. I believe the switch mechanism for all the functions is bad.

So I want to reform and test some ele. Caps at rated voltage and reform them. I am wanting to use my multimeters DC amperage setting to watch for leakage while I use another meter to monitor voltage.

I am thinking I should hook up one meter in parallel to monitor the voltage and the other in series with the cap to monitor leakage current. Is this correct?

Is that all I should have to do?

I plan on getting this thing working or parting it out for a cap reforming and leak testing build without all the fonky switching. But for now I just want to get some voltage through some caps with regulation so I can move on with a build that's been sitting awhile.

[martin manning]

A good way to reform caps is to place a large resistor in series with the cap that will limit current to a few mA into a dead short. A 100k 1W would be a good value to use, and the voltage across it divided by 100 will give you current in mA. Bring the DC supply up to the cap's rated voltage, and monitor the voltage across the resistor to get current. If the cap is good, eventually the current will drop to a very small value and the voltage across the cap will approach the supply voltage. this might take some time. Discharge the cap and repeat the process a couple of times before fully discharging and measuring capacitance.

[Stevem]

How old are some of the filters you’re looking to mess around with to reform?
You can really shoot yourself in the foot sometimes because reusing a to old reformed filter is never going to give even 1/8th of the life span that the filter had when new!

At least that’s been my experience, as 85% of the time it was just a big waste of time in hindsight.

[dragonbat13]

These are around 10 years old.

And there's some that are around 3 years old. Probably nothing wrong with them but I feel it's better to slowly charge them up out of circuit under a controlled condition instead of installed in the amp with a variac.

I have the power supply, so I figure it can't hurt. I'm not in a rush to get amplifiers out the door.