circuit board component???

[kadin]

hello

i have a qestion regarding the component below, i cant find anything online regarding the "double diode" symbol. is this a diode? doesn't seem to be as i cant get a reading from either pin. or does it need to be out of circuit? is it testable with a mm in circuit?
( on the front of the component is written fgh20a15 )
thanks

direct link to image

direct link to image

 

[jpanhalt]

May be a common cathode diode pair. Check out the BAT54C as one example. Diode arrays come in most possible arrangements.

NB: The pin arrangement for the BAT54C is different than the arrangement implied by the diagram on your board.

John

 

[Veraxis]

I couldn't find anything for FGH20A15, but I did find this for FCH20A15, which is a double diode. Judging by the PCB, they appear to be connected in parallel to act as a single high current diode.

http://pdf.datasheetcatalog.com/datasheets2/29/29502_1.pdf

It should generally be possible to measure a diode in circuit, unless there is a transformer winding or other component that is low enough impedance to look like a short across the diodes when it is in-circuit.

 

[Nigel Goodwin]

It's simply a double rectifier, commonly used for full wave applications, or (in this case) with the two halves paralleled.

As the two diodes are on the same piece of silicon they are going to be very well matched, so paralleling them in this way seems to work fine. At least it's pretty rare to ever see one fail.

 

[kadin]

I couldn't find anything for FGH20A15, but I did find this for FCH20A15, which is a double diode. Judging by the PCB, they appear to be connected in parallel to act as a single high current diode.

http://pdf.datasheetcatalog.com/datasheets2/29/29502_1.pdf

It should generally be possible to measure a diode in circuit, unless there is a transformer winding or other component that is low enough impedance to look like a short across the diodes when it is in-circuit.

Yes, that's probably the one, as the lettering is so faint. There are transformers in the circuit, whole board below. Well if they rarely fail, i'll leave alone & hope, i got lots more from other boards that i'll post in a new thread

Thanks all.


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