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[The_Almighty_Bacon_Lord]

Delete Delete Delete

[grifftech]

Where is the image?

[Ian.M]

Chances are the 'ghetto diode' is too slow for the application.  What's its part number?

ATX PSU diodes wont be any use if the rail the diode is for is over about 18V.  They wont have the voltage rating.

The original SR210 is probably this 2A 100V Schottky diode: https://www.wontop.com/uploadfiles/56/sort_excel/pdf/sr22.pdf
but we'd need exact dimensions to confirm that.

[Ian.M]

Yes. The 10A10 is a normal silicon PN junction power diode intended for 50/60Hz rectification.  You need a Schottky diode (or possibly an ultra fast 'normal' diode) for a switched mode boost circuit like that.   

Try the FR202 - it's got the voltage and current rating you need and *MAY* be fast enough.  If it runs hot you'll probably need to buy a 100V 2A Schottky diode  though if you've got some scrap boards from large screen CRT TVs or monitors, you may get lucky and find something suitable near the line output transformer or in the PSU.

[Ian.M]

I've edited above. Try FR202.

As to what the 10A10 diode is good for - well if you are building a HV DC motor drive or a real brute of a valve power amp with a linear PSU, it would be a good choice for use in the bridge rectifier feeding the high voltage bus.

[Ian.M]

In that case you are S.O.L.  The switching frequency must be too high for anything other than a Schottky.

[Ian.M]

No.  To get 34V for the backlight, the diode has to stand that + the inductor ringing when the current through the diode cuts off which can take its anode negative by the same amount, so it can have 70V across it.  Add a moderate safety margin and you are up to 100V.

A motherboard Schottky certainly wont have a 100V rating as the max voltage used for any rail is 12V.   Ratings may be as low as 20V.

[Ian.M]

Its just a best guess as there are a few other (much smaller) inductors on the board.  However the 34V backlight rail is a good match to the diode's 100V PIV rating.  If that voltage's gone AWOL and the other rails are OK, its conclusive evidence for it to be in the backlight boost circuit.   Other rails aren't likely to be >12V and any diodes in switching buck regulator circuits running off 12V don't need more than a 30V PIV rating.