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Reinhard Zwirner[_2_] Reinhard Zwirner[_2_] is offline
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Default Finding A Power Supply Schematic

Michael Karas schrieb:
[This followup was posted to sci.electronics.repair and a copy was sent
to the cited author.]

In article , says...



Is there a "bleed-through" route for start-up?


I do not really know what you are asking about here. ...


This

http://www.bilder-hochladen.net/files/big/12b4-a6-6c52.jpg

is a typical schematic for a SMPS. The supply voltage for the
controlling IC is provided via R1 for the first moment - I think this
is N_Cook's "bleed-through" route. When the circuit is working the
supply voltage is generated by W3/D1/C6.

If R1 is open and/or C6 has a short the SMPS won't start.

HTH

Reinhard