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Join Date: Aug 2006
Posts: 30

Switching power supply problems

05/11/2007 11:19 AM

I have one broken power supply with schematic as below:

at point A is 400V as normal but now is 270V and didn't have pulses.Checked IC L6561D is ok.Mosfet ok, bridge diod ok. all the resistor between A and B ok. does anyone can help me to solved this problems? Thank in advance !

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#1

Re: switching power supply problems

05/11/2007 11:28 AM

Dude what's up with your avatar? Do you have issues with women? While you obviously have some technical chops, I seriously question your maturity if you think that avatar is in any way appropriate.

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#3
In reply to #1

Re: switching power supply problems

05/11/2007 1:27 PM

What? You find NO WHITE WOMEN to be an inappropriate sentiment?

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#5
In reply to #1

Re: switching power supply problems

05/11/2007 2:14 PM

Maybe the OP avatar means "no nude picture"?

MidniteFighter

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#2

Re: switching power supply problems

05/11/2007 11:31 AM

I would like to help but the image is just too small, sorry I do not know how to enlarge it. Come on in and explain this so we can all know, I see various people have a much clearer understanding of how to manipulate images within CR4. So would those better aquainted help out. Thank you.

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There's them that knows and them that just thinks they know, whitch are you? Stir the pot and see what rises up. I have catalytic properties I get a reaction going.
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#7
In reply to #2

Re: switching power supply problems

05/12/2007 1:36 AM

the pic is too samll to watch. but you can download it to your computer and then enlarge use ordinary software.

its no problem for you.

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#12
In reply to #7

Re: switching power supply problems

05/12/2007 11:08 AM

I down loaded it just said un able to read doc.

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#14
In reply to #7

Re: switching power supply problems

05/12/2007 10:42 PM

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#4

Re: Switching power supply problems

05/11/2007 1:30 PM

No pulses? Is the gate of your mosfet pulsing?

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#6

Re: Switching power supply problems

05/11/2007 11:26 PM

Replace three Electrolytic capacitors next to diode bridge, your problem will be solved. I am not able to read values of capacitors presently used.

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#8

Re: Switching power supply problems

05/12/2007 1:56 AM

the pic is too deepth compression to acquire a clear view.

but I think its not a big problem.

measure the filter of X capacitor to see if it drains? generally speaking its of 102/800v

and one of the industor is broken?

first to recorve your 400v.

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#9

Re: Switching power supply problems

05/12/2007 2:43 AM

Nice invisible circuit diagram. Your avatar is clearly visible however, and has attracted the attention of our Heroes. It's a little peculiar I'll agree, but your choice no doubt.

You should firstly review your measurements - before and after - and think about what has changed between them, your measurement techniques, instrument and settings.

Then understand your circuit. There are several evil feedback loops and regulation sources in power supplies like this, so you will need to understand them, even to the extent of changing or removing them to check the effect is as predicted. Often the fault can be a long way away from the points at which you are likely to take diagnostic measurements.

Chuck it away and buy another one. Or buy another one so you can take reference measurements ........

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#10

Re: Switching power supply problems

05/12/2007 4:00 AM

it indeed not clear. but the model is common.

as above all point out if your measurement is not error, most of the failure part is at the filt inductor. try to think, if the filter capacitor or behind part fail to come out 270v voltage, the huge current will ocur and switcher will be broken heavily.

simple way, short the inductor!

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#11

Re: Switching power supply problems

05/12/2007 4:14 AM

I am having difficulty finding point A in the pic where you dont find pulse.....I mean the woman in your avatar. We would love to help u revive her !

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#13

Re: Switching power supply problems

05/12/2007 11:09 AM

If this circuit could be read it could be fixed.

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#15

Re: Switching power supply problems

05/13/2007 3:58 AM

Thanks for all comments. This is the schematic, hope you can see clearly. i don't know how to upload the big picture on CR4.

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#17
In reply to #15

Re: Switching power supply problems

05/15/2007 9:32 AM

Check the opto isolators.

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#16

Re: Switching power supply problems

05/14/2007 6:24 PM

Schematic isn't too clear but assuming the Regulation Loop isn't putting an excessive load on the Rectifiers output it sounds like a filter capacitor is shorted or installed in reverse. I'd remove the Regulator from the equation by lifting the supply leads to the Transformer. If the Voltage is still low then its definitly a partial short somewhere in the Rectifier/filter section and you should be able to find it with an Ohm-meter.

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Anonymous Poster (1); bhankiii (2); BrainWave (3); cnpower (3); Ganter (1); Haajee (1); kvsubramanyam (1); maufi (1); MidniteFighter (1); QSK (1); Silas Marner (1); wmstutz (1)

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