I have a low power mains operated HID lamp power supply with a problem I am trying to diagnose. My question is what exactly is this diode, Panasonic B2ZAZ0000020. Looks like a standard 4A axial lead high speed diode. No conductivity in either direction, not even a uA till you get to about 250V. This is located on the primary of a H bridge driven ballast. I've searched to no avail and know it is bad. Others have reported that good ones conduct in one direction. My guess this is one of those TVSS high speed zeners used in clamping surges and that the internal reverse diode has failed open. My usual source is back ordered for more than a month. Any designers know if TVSS diodes are used in these supplies? I'm about ready to parallel the bad one with a high speed diode and see if it will work. I can eventually get the correct diode, but really curious of what this is. Never seen a diode fail like this.
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