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Visual Signs of Capacitor Failure - Bulging

Jan Cumps

I received a new TV box from the cable provider They suggested to drop the old one at an electronics recycle collector. That didn't happen Slight smile - I opened it up. I've put the internal hard drive for sale on a 2nd hand site. For the other components, I'm checking what (if anything) is worth keeping.

What caught the attention, is that one of the electrolytical caps is beyond end-of-life. It's definitely bulging: It's the first time that I see one where the symptom is so obvious. I had others that failed or leaked. But never such a visible sign of the internal pressure effects.

image

Can you spot the culprit?

Title inspiration: capacitor labs.

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  • Jan Cumps said:

    Yes. I have seen these low-budget caps many times.

    Such caps were terrible in a project with our customer.
    We had built a communication device with route recording for the ÖBB (Austrian Federal Railway).
    The power supply of this device had an electrolytic capacitor built in that was sensitive to temperature.
    How? What? ----- Well, in the higher regions the ambient temperature can quickly drop very low even in summer.
    One day the customer came with such a defective device.
    I tested it, but at first I couldn't find any fault. - At room temperature in the workshop.
    Then I took a cold spray or a hot soldering iron tip and looked for components to see if they were temperature sensitive.
    Voila, one of these electrolytic capacitors clicked when it cooled down. Its capacity was suddenly only half or it was causing a short circuit.
    I then had to drive across the country and replace these electrolytic capacitors.
    There were about 100s of devices.

    Oh yes... with a capacitor like this it can be quite annoying because you can't see this kind of error from the outside.

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  • Jan Cumps said:

    Yes. I have seen these low-budget caps many times.

    Such caps were terrible in a project with our customer.
    We had built a communication device with route recording for the ÖBB (Austrian Federal Railway).
    The power supply of this device had an electrolytic capacitor built in that was sensitive to temperature.
    How? What? ----- Well, in the higher regions the ambient temperature can quickly drop very low even in summer.
    One day the customer came with such a defective device.
    I tested it, but at first I couldn't find any fault. - At room temperature in the workshop.
    Then I took a cold spray or a hot soldering iron tip and looked for components to see if they were temperature sensitive.
    Voila, one of these electrolytic capacitors clicked when it cooled down. Its capacity was suddenly only half or it was causing a short circuit.
    I then had to drive across the country and replace these electrolytic capacitors.
    There were about 100s of devices.

    Oh yes... with a capacitor like this it can be quite annoying because you can't see this kind of error from the outside.

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