Polar Instruments TONEOHM 950 - Section 4 Operation; Locating Faults with the TONEOHM 950; Range Selection; Low Resistance Shorts

CONTENTS
xi
3.4 Ranges.........................................................................................................................................3-3
Track Resistance.......................................................................................................................3-3
Track Current.............................................................................................................................3-3
SECTION 4 – OPERATION ......................................................................................................................4-1
LOCATING FAULTS WITH THE TONEOHM 950 ................................................................................4-1
4.1 Range selection ...........................................................................................................................4-1
4.2 (Low resistance) shorts................................................................................................................4-2
Example – Low Resistance Short ..........................................................................................4-2
4.3 Plane Shorts ................................................................................................................................4-3
Causes of Shorts on Multi-layer Boards ....................................................................................4-4
Connection.................................................................................................................................4-4
Sensitivity Adjustment................................................................................................................4-5
Operation (Single Short) ............................................................................................................4-5
High Resistance Shorts..........................................................................................................4-6
Multiple Shorts .......................................................................................................................4-7
Segmented Planes.................................................................................................................4-7
Non-Rectangular Boards........................................................................................................4-7
4.4 Track current measurement ........................................................................................................4-8
Excessive Vcc Loads ...............................................................................................................4-10
Example – Excessive Vcc Load...........................................................................................4-11
Example – Multiple Current Paths........................................................................................4-12
4.5 Current Tracing (non-contact)....................................................................................................4-13
Locating faults using TRACE...........................................................................................................4-13
Connection and Sensitivity Adjustment....................................................................................4-13
Operation .................................................................................................................................4-14
Bus Faults (Stuck Nodes) ........................................................................................................4-15
Edge Connectors .....................................................................................................................4-16
Faulty Decoupling Capacitors ..................................................................................................4-17
4.6 Track voltage measurement ......................................................................................................4-18
Example – Excessive Vcc Loads .........................................................................................4-19
SECTION 5 – MAINTENANCE AND CLEANING.....................................................................................5-1
5.1 Calibration requirements..............................................................................................................5-1
5.2 Plane Stimulus Protection Fuses.................................................................................................5-1
5.3 Cleaning.......................................................................................................................................5-1
5.4 Technical Support........................................................................................................................5-1
SECTION 6 – APPLICATION NOTE ........................................................................................................6-1
QUESTION ABOUT PLANE SHORTS..................................................................................................6-1
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