while floating server PSU's burned tvs diode (4 in series)

Thread Starter

bigjoncoop

Joined Feb 1, 2019
167
hey Guys,

recently I've been using some 2 HP server power supply connected in series to make 24 volts. doing so by floating one of them so mains ground not connected to dc output

they have been working great. Until today I tried to add a 3rd power supply in order to make 36 volts. when I floated this one I forgot to disconnect one of pigtails coming off the PCB to the chassis.

as soon as I connected in series with the other two the Magic Smoke came out. there is 4 tvs diodes that seemed to be in series and one side was connected to the grounded pigtail I forgot to remove. the power supply still seems to work but I'm wondering if I should replace the the burned TVS diode... I have a feeling since the power supply still works that those TVS diodes are only being used if the output is grounded and not floated. which I think I should be fine without replacing it.

the diodes are:
SMAJ5.0A Marking: A E 400W SMA DO-214AC SMD TVS DIODE

just wanted some Input. Thx

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