I have a BK Precision 1665 0-20V variable SMPS. When I got it, it had 2 burned out switching MOSFETS, IRF840A and 2 shorted 1N4744A zener diodes on the MOSFET driver circuits. The driver transistors test good. I was unable to find any more shorted semiconductors.
Problem is, after and even before replacing those parts, when using a 100W bulb in place of the fuse and I turn on the PSU, the bulb blinks and the panel lights go out. The bulb blinks at full brightness and when it is off, it is completely dark. The front panel is lit when the bulb is off, dark when bulb is lit. It blinks at a steady rate, just like the turn signal on a car.
It was doing this even with the bad parts removed, and it does the same even with the new parts installed. New parts seem not to have been harmed.
Any ideas what I should check?
Problem is, after and even before replacing those parts, when using a 100W bulb in place of the fuse and I turn on the PSU, the bulb blinks and the panel lights go out. The bulb blinks at full brightness and when it is off, it is completely dark. The front panel is lit when the bulb is off, dark when bulb is lit. It blinks at a steady rate, just like the turn signal on a car.
It was doing this even with the bad parts removed, and it does the same even with the new parts installed. New parts seem not to have been harmed.
Any ideas what I should check?
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