[WriteLog] W5XDKeyer Help - Bridge Rectifier Mis-Labeled??

[Ed Sleight]

Dan Levin wrote:

The DB101MS 1A bridge rectifier that I received from Digi-key has 4 pins
marked "+", "-", "~" and "~".  There is a "+" marked next to one pin on
the silk-screen of the board. There is no orientation that allows the
part to be mounted on the top of the board and the "+" on the part to be
matched to the "+" on the board.  See diagram below:
Part is like this:
 
 +   ~
 
 -   ~
 
OK, the very first possibility I would check is that the rectal fire is
mislabeled. This can easily be checked. But first, assuming the output
of the power supply is a + voltage, the following applies. The + is the
positive unfiltered output of the rectifier. The - is the negative
unfiltered. The ~ are for ac input voltage. Makes no difference which
side of the ac line goes to either one.

To check it for mislabeling, use some jumpers and connect the ac to the
2 ~ pins, connect a VTVM to the + and - pins and plus it in, making sure
you have the VTVM RED lead to the +. If the device is properly marked,
you will have a positive reading on the meter. If the voltage on the
meter is negative, then the rectifier is not correctly labeled. Which is
no big deal. Just correct the markings.

Now, there is a possibility that the output voltage is designed to be
negative. So before you insert that sucker in the board, check the
schematic and see if the first electrolytic down stream of the bridge
has the - on the capacitor to ground or the + to ground. IF the + is to
ground, the output is designed to be negative. Of course, the opposite
also applies.

Hope this helps...brings back memories

73
Ed

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