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Old 24th Apr 2019, 7:05 pm   #9
MrBungle
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Join Date: Jun 2016
Location: London, UK.
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Default Re: HP 6024A power supply FET.

Good find. Don't agree with TO220 though. Not enough for this supply.

Spent a few minutes looking at this. Looking at the specifications and schematics I would replace A4Q1, 2, 3 and 4 (assuming all are populated?). These were apparently fitted with 1855-0473 originally. Someone has reported success with IRF450 as a replacement for that part [1] and it looks about right on spec sheet as it's primary side switching.

Now the pain with this is the IRF450 is really expensive or from hooky suppliers only now. After reading further, old FETs never die. IRF450 is now sold as an IRFP450 in TO-247 package! So options are spend £££ or bodge IRFP450's in. The latter are £2.47 a go from Farnell so I'd probably go there.

Disclaimer: EXPECT FIREWORKS.

Edit: also expect that it may have blown whatever drives the gate if the drain flashed over to gate as well. Last time I had a preregulator go on me, it took the following bits out in one go:

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[1] http://www.simonsdialogs.com/2014/09...supply-repair/
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