hello everybody first post on the site. my company does some board repair and we came across an object that i cannot identify. this is a larger surface mount package measuring at 0.236" x 0.26" with a designation of CR. all black on top with etching IR3f9742L. to me this indicates a diode by international rectifier (infineon technologies now) possibly package 723fl but i cant find anything guaranteeing that on the web. i have ST5s smart tweezers and on the diode setting it shows a forward voltage of 0.23V. can anyone assist me in figuring out this diodes true number? anything would be appreciated. if i am inside of the wrong location please let me know. after reading the post in the sticky i am confident it is just a general electronics question.

thank you
Ryan

 

A picture is worth a thousand words. So post a pic of it. Also have you try to reverse-engineer the surrounding circuit?

 

Here is an image of the side of the board where these take place this is a newer revision of the board i found in scrap bin it has some lifted traces on the other side. these ones are labeled V3FP142L which finally returned a search for a p142L i guess i may have figure it out. with this being said, these diodes are often a problem within the circuit. the caps we often change to 35V caps because they tend to take alot of damage to them, but i couldnt find a replacement for the diodes ill look into this further.

so a quick description of the board.

it has 26V AC in on other side directly into a bridge rectifier and through some large caps then into this side where the DC circuitry is. here we hace a 9V VR a 12V VR and a 5V VR. quick inspection of the circuit shows me these are only for protection. each female socket on either side of the board does have data pins, AC voltage and DC voltage's running into each one. i am designing a schematic and circuit for this board to make it a more simple repair for the techs that are hired, and was hoping someone might have a quick answer for me.

 

I think that all of these diodes will be Schottky diodes commonly used in DC/DC converters, 3A/40V or more. Simply try to find the VR1 and VR3 IC datasheet to be sure about the current riting.

IR3F marking
http://www.farnell.com/datasheets/13169.pdf

 

I think that all of these diodes will be Schottky diodes commonly used in DC/DC converters, 3A/40V or more. Simply try to find the VR1 and VR3 IC datasheet to be sure about the current riting.

IR3F marking
http://www.farnell.com/datasheets/13169.pdf

Thank you Jony for replying to this i truly appreciate it. i will also take a look at the TI datasheet for the VR's i dont know why i didnt think of that in the beginning. this datasheet you supplies does seem to be closer match than to anything i have found so far