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Switch Mode PSU

 
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miox
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PostPosted: Mon Jul 07, 2008 6:22 pm    Post subject: Switch Mode PSU Reply with quote

hi there, i have a 24 volt switching power supply that has fried its quad opamp "LM324N" i did replace the chip but it still got fried, i measured the output of the psu and it was over voltage by 200% "70-75 volts" i did check some parts eg, capacitors and resistors and some diodes and its all ok, can any one pls help tnx
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vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Tue Jul 08, 2008 3:58 am    Post subject: Re: Switch Mode PSU Reply with quote

miox wrote:
hi there, i have a 24 volt switching power supply that has fried its quad opamp "LM324N" i did replace the chip but it still got fried, i measured the output of the psu and it was over voltage by 200% "70-75 volts" i did check some parts eg, capacitors and resistors and some diodes and its all ok, can any one pls help tnx


Depending on your circuit design, sounds like you may have somehow lost a feedback signal which could be many things?-w/out a diagram, it is not going to be easy. Over 200% increase in output during failure? Wow Not a very good design I might add!?
Not sure if I'd even trust using such a device as it will likely damage whatever is powering. Wink
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miox_24



Joined: 07 Jul 2008
Posts: 5

PostPosted: Wed Jul 09, 2008 6:22 pm    Post subject: Reply with quote

Very Happy
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miox_24



Joined: 07 Jul 2008
Posts: 5

PostPosted: Wed Jul 09, 2008 6:29 pm    Post subject: Reply with quote

Very Happy yes sir ur ryt, i found & replaced a deffective shunt regulator "TL431" in the reg ckt. thanks a lot
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