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As the title says, I accidentally ripped the lead off this film capacitor. It was the only one I had - am I out of luck, or can this be soldered back on? I've provided photos, including one under my microscope of the damaged area.

This appears to be a 2 μF, 400 V film cap with a 5% tolerance (the J letter code). It's easy enough to replace; I have found a few on Mouser that are relatively inexpensive ($3.50 USD), but wanted to see if it was worth trying to repair before I ordered some.

Separate question - as mentioned, I found some replacements (from Panasonic). Does anyone recognize the manufacturer of the one pictured? These were taken from the inside of an Tripp-Lite isolation transformer.

Ripped off capacitor lead

Ripped off capacitor lead under microscope

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    \$\begingroup\$ I would avoid trying to do this type of repair on anything that goes on mains, is rated for 400V and costs 3 bucks. \$\endgroup\$
    – Wesley Lee
    Jan 28, 2023 at 16:17
  • \$\begingroup\$ Is there a part number on the back? \$\endgroup\$
    – Voltage Spike
    Jan 28, 2023 at 16:25
  • \$\begingroup\$ @VoltageSpike no, the only labelling is what's shown in the images provided (which is enough for me to find a replacement) \$\endgroup\$
    – riptusk331
    Jan 28, 2023 at 16:43
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    \$\begingroup\$ You'll deform the plastic film if you try to repair it, resulting in a part with unknown max voltage and capacitance ratings. Capacitance you could measure, max voltage, not really. \$\endgroup\$ Jan 30, 2023 at 10:24

4 Answers 4

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Do not try to repair the capacitor. You're more likely to create a short and possibly damage something else in the circuit. Just buy a suitable replacement.

The leads are connected with the edge of the coiled metalized plastic (likely polyester aka Mylar) film by a layer of sprayed metal (called "Schoopage" after Swiss engineer Max Schoop who developed the process). You cannot easily reproduce it without specialized equipment. It's not a strong connection and the epoxy dip or powder coat provides much of the strength. So-called "box" capacitors are potted in a plastic housing and are more immune to mishandling.

There are many manufacturers of film capacitors, particularly in Asia. Personally I don't recognize that logo. It's not very important anyway.

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    \$\begingroup\$ thanks for the detailed answer and interesting background! already ordered replacements based on the responses here. \$\endgroup\$
    – riptusk331
    Jan 29, 2023 at 2:25
  • \$\begingroup\$ @riptusk331 and from what I can tell, they're rather cheap. \$\endgroup\$ Jan 31, 2023 at 16:16
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It really is not worth trying to attach the leg back to capacitor. The layers may have suffered mechanical damage. Buy a new one.

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The first problem is you would have to know how the pin is attached, either by welding or soldering, they reattach it by removing the epoxy and then applying new epoxy. This would cost you well over the cost of getting a new capacitor.

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Maybe electrically conductive epoxy? Or see if a solder joint works and then coat in normal epoxy for strength? But as others have said, it’s really not worth the risk.

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