A Deeper Look At Capacitor Leakage 

Week ago i got one Telequipment D755 and it was dead as a dodo. Main filtering caps we're gone, started to leak. Interesting fact was that they tested "good"(capacitance and esr) on my Voltcraft lrc-300 meter.I didn't bother to test leakage current, cause i still didn't made diy instrument for that and i wasn't up for making setup using bench psu, a-meter and couple of wires,but my guess they got pretty high leakage current. After i replaced them scope came to life. After that i replaced all other caps on psu board, but managed to solder one wrong way, so there was a bit white smoke involved. I guess you are not only one who makes this small mistakes. haha But how much i recall this was first time i soldered cap wrong way. And ofc great video as usual. I really love your channel.

The date code on your cap is in the 70, all it needs is re-form with proper method, It will then be better any “modern “ cap, I assured you that. The MepcoElectra catalog have the electrolytic cap tutorial and re-form methods. Thanks for the video!

Hi, great explanation 👍, I was recently troubleshooting the capacitors in an old HP3400 meter and it freaked me out that some of the 40 year old Sprague capacitors had less leakage than the newly bought replacements - the quality isn't what it used to be. Since I live in the Czech Republic and the USD/CZK exchange rate is not good, as well as my salary, I can forget about buying an SMU as an electronics amateur, I looked at what is available on the market and bought an AT680 - it works absolutely luxuriously for a fraction of the price of an SMU. It does not replace the four-quadrant measurement, but I tested not only the capacitors, but also the insulation resistances of the device, the function of the digitrons, diodes, etc., and the 650V voltage provided by them is sufficient for my applications In order to buy SMU, I would have to sell my body organs and it might not be enough yet 😂 Nice day 🙂 Tom

Thank you for posting the video, very interesting. I’m sure you know this already, but you can set the source voltage to 0 on the SMU and it will discharge the cap for you.

I find the Keithley running all the time up minute 22.00 in the background by side the Fluke a little distracting.