Author Topic: PSU question  (Read 1208 times)

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Offline angelothewolf

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PSU question
« on: October 10, 2014, 02:13:38 pm »
Hi there!! im working with this power supply that is delivering 38VDC where it's supposed to be 25VDC. Should R205 adjust this voltage? got 35VAC coming out of the transformer and 41VDC after rectifier on filter caps...  ??

 

Offline angelothewolf

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Re: PSU question
« Reply #1 on: October 10, 2014, 04:26:25 pm »
nobody?  :scared:
 

Offline w2aew

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Re: PSU question
« Reply #2 on: October 10, 2014, 05:32:27 pm »
Hi there!! im working with this power supply that is delivering 38VDC where it's supposed to be 25VDC. Should R205 adjust this voltage? got 35VAC coming out of the transformer and 41VDC after rectifier on filter caps...  ??


Perfectly normal to see a larger DC voltage after the bridge rectifier, so no sweat there.

If everything was operating normally, then yes, R205 should adjust the regulated output.  However, it is possible that he pass transistor T201, or the regulator IC itself have failed.  Measure the voltages around the pass transistor.  Do they make sense?  What voltages do you see on the regulator IC pins - do they make sense?
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