Blown Strobe Power Supply

[Tparker]

I have acquired a 90 watt, 4 outlet strobe light power supply as used on emergency and construction vehicles. The 15 amp on board automotive type spade fuse has been destroyed and the circuit board around the input side of the fuse holder shows a burn mark but the foil has not lifted.
The rest of the circuitry, including the step-up transformer appears to be undamaged (no sign of overheating or burning). I suspect either one or both of the step-up mosfets (HUF75639P, 100volt, 56 amp, .025 ohms) have failed. Is there any way to test or elimenate these mosfets as the culprits? By the way, the manufacter claims these power supplies are short circuit and reverse polarity protected. Thanks in advance for any help before I chunk it in the garbage.

[Tparker]

Nevermind, not sure what I did but I got it working after opening the case (riveted), removing the mosfets from the case bottom where they were bolted for heatsinking and cleaning and resoldering the one side of the fuse holder. Only thing I can think of is either the fuse holder was shorting to the case where it protrudes thru or the mosfet heatsink insulators were grounded. It seems the reverse polarity diode worked but it sure played heck with the fuse and holder.

[jollyrgr]

Quite possibly there was a cold solder joint by the fuse. This created a point of "high" resistance which overheated.

[dacflyer]

if anyone needs strobe supplies repaired,,i am the one... i repair all kinds.. heavy duty ones from radio towers to airport runway strobes...also repair the slammer types on aircraft and party / emergency strobes..i have a source for almost any tube too...just giving me 2 cents worth....