I was asked to look at a Taco VFD that would not power up. This particular model was discontinued and the replacement cost was more than double the cost of brand new unit. Examined the SMPS and it was clear what the issue was. A number of capacitors had leaked. Based on the design of the SMPS I wouldn’t be surprised that the caps had been leaking for some time. Did a bit of troubleshooting to see if any other parts were damaged as a result, and yes there were.
Ordered parts from one of local suppliers. Due to pandemic restrictions was not able to look at parts before I got them Surprise surprise, parts were the cheap variety, the kind that would fail in a short time and probably do much more damage. Installed those parts temporarily to verify unit functions, and it did. Ordered high grade parts that had better specs than the original. Picked those up a day later, and the unit was back in service. Received a message a few days later that the unit failed again. Whatt?? .
Checked the unit and found another failed component. Based on how it was connected in the circuit, it became clear that this part was weakened from the time of original failure. Although it tested good the first time I examined it, it was not in a position to operate for much longer. I replaced that part and the unit has now been working for two months.
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