Prof-check this schematic (Please!!!!!)

ifrythings · 29th August 2006, 05:45 AM

I copied this schematic off of an ATX power supply, it's the stand-by circuit.

The transformer is a 1 primary, 1 feedback on the same side and one center tapped secondary.(I didn't have the right symbol in my program so I stuck two together)

Only other thing I notice was on the board they had a spot of a resistor going for the emitter of 2SC3150 to base of 2SC945. Any ideas what that mite of been for?

ifrythings · 30th August 2006, 01:06 PM

Bump.

No one has any thoughts on this?

sawreyrw · 30th August 2006, 10:11 PM

Someone might comment on this if you show the transformer inductances or turns ratios. Further, the 103 and 151 caps don't make sense.

ifrythings · 30th August 2006, 11:31 PM

151 is 15 +1 zero (0) so 150pF
103 is 10 +3 zero (0) so .010uF or 10nF

transformer inductance is: Feedback is 5.5uH, Primary is 4.42mH

btw most ceramic disc capacitors have the marking like 104, 103 things like that just in case you weren't sure.

koolkid731 · 12th September 2006, 04:46 AM

It looks like a self-oscillating switcher, not very efficient but cheap. I've seen a 25-watter using that scheme.

AJT · 14th September 2006, 02:22 AM

Quote:

Only other thing I notice was on the board they had a spot of a resistor going for the emitter of 2SC3150 to base of 2SC945. Any ideas what that mite of been for?

it is used to limit the base drive to the chopper trannie, you shouild use that.

12th September 2006, 04:46 AM	#5
koolkid731 diyAudio Member Join Date: Jan 2005 Location: Sonoma, California	It looks like a self-oscillating switcher, not very efficient but cheap. I've seen a 25-watter using that scheme. __________________ Koolkid

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30th August 2006, 01:06 PM	#2
ifrythings diyAudio Member Join Date: Oct 2005	Bump. No one has any thoughts on this?

30th August 2006, 10:11 PM	#3
sawreyrw diyAudio Member Join Date: Apr 2006 Location: Minnesota	Someone might comment on this if you show the transformer inductances or turns ratios. Further, the 103 and 151 caps don't make sense.

30th August 2006, 11:31 PM	#4
ifrythings diyAudio Member Join Date: Oct 2005	151 is 15 +1 zero (0) so 150pF 103 is 10 +3 zero (0) so .010uF or 10nF transformer inductance is: Feedback is 5.5uH, Primary is 4.42mH btw most ceramic disc capacitors have the marking like 104, 103 things like that just in case you weren't sure.