How The Leakseeker Works - EDS LeakSeeker 89 Operation Manual

Preliminary
The LeakSeeker model EDS-89 will locate a shorted or leaky component or any other
shorted condition (such as a pinched wire or solder bridge) with a short resistance value
from zero to 300 ohms, to the exact spot on a pc board. If the unit has multiple pc boards,
LeakSeeker will first identify which board contains the defective component, then will
guide the technician directly to the location of the defective component on that board.
The EDS-89 version is an updated version of the original LeakSeeker EDS-82 series with
three sensitivity modes, all fully automatic. Tests are done simply by touching the solder
pads along a "shorted" foil trace and the pad with the highest pitch marks the defect.
This unit includes a universal AC adapter with a 2.1mm plug. The internal regulator in
LeakSeeker allows it to run from any AC or DC adapter or battery from 9 to 25 volts AC
or DC, as long as it has a 2.1mm plug.

How the Leakseeker works

The EDS-89 LeakSeeker pinpoints the exact location of a shorted or leaky component by
comparing the resistance at different component solder pads along a shorted pc foil trace,
and subtracts the foil's milliohm resistance from the value of the defective component.
Therefore, there is a different reading at each pad, although by a very small amount, with
the lowest reading at the short. Leakseeker consists of a 16 bit self-calibrating digital
comparator with a range of zero to 300 ohms, auto memory, and a variable gain
comparison circuit with visual and audible indicators. Initial search for a shorted
component automatically starts at the LeakSeeker's maximum range and counts down to
the resistance of the defective component, within a "window" that is indicated by nine
small distance LEDs. It also uses a variable pitch tone, which will be at its highest when
the test probe is touching the pad where the resistance is lowest.
LeakSeeker can use one of two different test methods to locate the defect. The NORMAL
test causes a precise voltage/current to appear at the test PROBE, and as the technician
touches each pad, the small difference in the voltage/current readings is translated into
the change of the beep pitch and distance LEDs. This test method is ideal for finding the
location of typical "dead" shorts under a few ohms.
The 3-WIRE test is used when the readings are confusing, for example, if the "short" is
actually many ohms, and a large electrolytic capacitor is somewhere along the trace.
Instead of a steady tone, the pitch may constantly change as the capacitor tries to charge
or the leaky defective component warms up, making stable readings impossible. The 3-
WIRE test separates the precise voltage reference +REF from the PROBE port. It is
more difficult to use, so the technician should have a thorough understanding of the
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