« previous next »
Pages: [1]   Go Down

Author Topic: PSU question  (Read 1601 times)

0 Members and 1 Guest are viewing this topic.

Offline angelothewolfTopic starter

  • Contributor
  • Posts: 43
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...  ??

Logged
 

Offline angelothewolfTopic starter

  • Contributor
  • Posts: 43
Re: PSU question
« Reply #1 on: October 10, 2014, 04:26:25 pm »
nobody?  :scared:
Logged
 

Offline w2aew

  • Super Contributor
  • ***
  • Posts: 1780
  • Country: us
  • I usTa cuDnt speL enjinere, noW I aR wuN
    • My YouTube Channel
Re: PSU question
« Reply #2 on: October 10, 2014, 05:32:27 pm »
Quote from: angelothewolf 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...  ??


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?
Logged
YouTube channel: https://www.youtube.com/w2aew
FAE for Tektronix
Technical Coordinator for the ARRL Northern NJ Section
 
Pages: [1]   Go Up
« previous next »

Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf

 


EEVblog Main Site EEVblog on Youtube EEVblog on Twitter EEVblog on Facebook EEVblog on Odysee