Identify an SMD component

From: Scott Stevens <sastevens_at_earthlink.net>
Date: Sun Aug 29 19:51:31 2004

On Sun, 29 Aug 2004 19:43:07 -0400 (EDT)
der Mouse <mouse_at_rodents.montreal.qc.ca> wrote:

> >>>> The black plastic SOT-23 package is marked with 5A followed by a
> >K>>> rotated 90deg counter-clockwise.
> >> This says to me "five-amp rectifier pair", especially if [...]
> > Are you suggesting a 5A diode (or diode pair) in an SOT23 package?
> > I would be _very_ suprised.
>
> I don't know the SOT23 package. I do know I have seen surface-mount
> devices I would have no trouble believing capable of carrying five
> amps. This is another reason I asked for pictures, if possible; if
> (as I infer from your note) the SOT23 package is too small for it to
> plausibly hold a five-amp device, that theory slips down the list.
>
> As I noted, though, I'd be surprised to see such a thing on a 72-pin
> memory module. :-)
>
> > More like the '5A' is a code for the diode type.
>
> That's one plausible other theory I have, too. A third is that the
> device is something more like a voltage regulator and the CR
> designation on the board does not indicate a rectifier, but instead,
> perhaps, a parts-list code, or maybe refers to some other device, or
> whatnot. Another reason to want pictures: to estimate how plausible
> some of those theories are.
>
> > Can you figure out what it's connected to (do any of the connections
> > go to supply lines or ground, for example).
>
> Yet another reason I'd like to see pictures. Many memory modules
> include solder pads for some large-size module; for a module of (say)
> half that size, only some of the RAM chips are installed. Such
> modules not infrequently include solder pads for what I might loosely
> call jumpers, to indicate the module size. It would not surprise me
> if that's what this device were - and if, for example, there are
> similar pads nearby with nothing attached on either stick, that would
> reinforce the theory.

Perhaps he should use a DMM to carefully ohm out the part on the
non-damaged module. If it's a diode it will conduct only one way. If
it's a zero ohm shunt it will read as a short. Or it might be a
capacitor.
Received on Sun Aug 29 2004 - 19:51:31 BST