EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: scsi on July 24, 2019, 07:24:10 am
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Hello all,
I am testing ultrafast rectifier diode with DMM (internal schematic attached)
pins 1 - 2 reads diode drop (0.6V) reverse (infinity)
pins 2 - 3 reads diode drop (0.6V) reverse (infinity)
pins 1 - 3 reads short
Is this a normal behavior?
[attachimg=1]
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Should not be. Are you sure you have the right diode?
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original part in question is U1640G in TO-220 package and it is from SMPS so it must be ultrafast rectifier ^-^
desoldered one pin and it still reads short accros 1 - 3 pins.
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original part in question is U1640G in TO-220 package and it is from SMPS so it must be ultrafast rectifier ^-^
desoldered one pin and it still reads short accros 1 - 3 pins.
Oh, you are measuring in-circuit. Then your initial measurement was OK because often those diodes are used in parallel, pins 1-3 tied together. Why you still measure short between anodes - dunno. Perhaps you think you desoldered one pin but actually did not?
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Perhaps you think you desoldered one pin but actually did not?
Might be, these double sided commercial pcbs are pain to desolder without damaging the pads.
Thanks for the info!
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I propose title "is my common cathode diode assembly broken?".
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Oh, you are measuring in-circuit. Then your initial measurement was OK because often those diodes are used in parallel, pins 1-3 tied together.
Or the two diodes are connected to different points on the same transformer winding producing the same result.