On Tue, Feb 10, 2015, at 10:01 AM, Dean Posekany wrote: > > On 2/10/2015 3:00 AM, Gene Heskett wrote: > > snip > > The diode checker of the modern meter reads the voltage drop, fwd > > direction on this type of diode s/b under .15 volts, while the reverse > > of the probes should show a much higher voltage, maybe even off-scale > > for reverse. Right where they sit in circuit. A reading in both > > directions that is similar and probably under .1 volts is a shorted one. > > I checked the three diodes on the bottom near output port and they all > read generally the same: forward bias ~0.48V and reverse bias ~1.47V. I > checked a few of the topside diodes of the same value and got: forward > bias ~0.48V and reverse bias .OL. It appears that the bottom diodes are > bad. >
Not neccessarily. You are testing them in-circuit, and the 1.47V might be a completely different path through some other part(s) on the circuit board. The 0.48V forward voltage seems reasonable. Usually a shorted diode would read lower than that, and the same both directions. If they look scorched, it probably isn't a bad idea to replace them anyway. I'm sure they're less than $1 each, the main issue might be unsoldering and re-soldering if you're not familiar with surface mount stuff. If you do unsolder one, test it with the meter again, and see if the reverse readong goes up to .OL. I wouldn't be at all surprized. -- John Kasunich [email protected] ------------------------------------------------------------------------------ Dive into the World of Parallel Programming. The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
