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Old 11th January 2009, 05:57 AM   #1
PM650 is offline PM650  United States
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Location: Tennessee
Default SMPS repair has me stumped

I receiver a BASH subwoofer amp to repair, and the smps was (is) dead. One mosfet was shorted and D2 was turned black (see schematic below). I was unable to determine the original part no. of D2 or the orientation, so I installed another 4148 (silk-screen actually shows cathode on both ends...) in series with D1.
All of the resistors, except for R2/3/12/13, were turned dark green due to heat (originally bright blue). All resistors were still within tollerance, but I decided to replace them all, along with both fets and the lone transistor.

I am pretty sure the taps for C4/5 on the primary are shown wrong on the schematic, but it should still give a good idea.

1N5245B = 15V zener
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Old 19th January 2009, 05:59 AM   #2
jtkraj is offline jtkraj  India
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I did not get what do you want...
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Old 19th January 2009, 09:23 AM   #3
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Diode D2 it is an 32V Diac used for turn on the smps at power on.
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Old 19th January 2009, 10:56 PM   #4
PM650 is offline PM650  United States
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Quote:
Originally posted by jtkraj
I did not get what do you want...
What I wanted was an opinion on why it still doesn't work, and possibly why. As the title says, I have been unable to repair it so far.

Quote:
Originally posted by adi109cj
Diode D2 it is an 32V Diac used for turn on the smps at power on.
Thank you, I will try replacing it once I order some parts. I guess the diac symbol would explain the double cathode on the silkscreen.
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