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Polar Instruments TONEOHM 950 Operator's Manual

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Polar Instruments Ltd.
TONEOHM 950
Garenne Park
Rue de la Cache
OPERATOR
St. Sampson
Guernsey
MANUAL
Channel Islands
GY2 4AF
England
http://www.polarinstruments.com
Fax: +44 (0)1481 252476
Email: mail@polarinstruments.com
MAN 129–9803
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

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  • Page 1 Polar Instruments Ltd. TONEOHM 950 Garenne Park Rue de la Cache OPERATOR St. Sampson Guernsey MANUAL Channel Islands GY2 4AF England http://www.polarinstruments.com Fax: +44 (0)1481 252476 Email: mail@polarinstruments.com MAN 129–9803 Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 2 Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 3 TONEOHM 950 MULTILAYER SHORTS LOCATOR OPERATOR MANUAL POLAR INSTRUMENTS LTD. HARDWARE WARRANTY Product Warranty. Product hardware is warranted to be free from defects in material and workmanship during the Warranty Period (as defined below). Product hardware is warranted to conform substantially to Polar’s then current (as of the date of Polar’s product shipment) published user documentation during the Warranty Period.

  • Page 4: Declarations

    EC Council Directive 73/23/EEC on the harmonisation of the laws of the Member States relating to electrical equipment designed for use within certain voltage limits. A declaration of conformity with the requirements of these Directives has been signed by: POLAR INSTRUMENTS (UK) LTD 11 College Place London Road...

  • Page 5: Safety

    SAFETY SAFETY WARNING The LIVE and NEUTRAL lines on this unit are BOTH fused. This unit contains no user-serviceable parts. When the unit is connected to its supply, the opening of covers or removal of panels is likely to expose dangerous voltages. To maintain operator safety, do not operate the unit unless the enclosure is complete and securely assembled.

  • Page 6: Power Supply

    Retain these instructions for later use. The TONEOHM 950 is designed for use indoors in an electrical workshop environment at a stable work station comprising a bench or similar work surface.

  • Page 7: Specifications

    SPECIFICATIONS SPECIFICATIONS Track Resistance RANGES [Ω], 200mΩ, 2Ω, 200Ω, 20KΩ. Instruments with serial numbers below 005975 have a 2KΩ range instead of 200Ω. ACCURACY +/-6% in 200mΩ +/-5% in 2Ω +/-4% in 200Ω +/-5% in 20KΩ High sensitivity, uncalibrated. [Ω] RANGE Approximately 40mΩ...

  • Page 8: Environmental Operating Conditions

    TONEOHM 950 OPERATOR MANUAL OUTPUT VOLTAGE 0 to 550mV, adjustable. AC in TRACE, DC in all other ranges. PROTECTION Protected to +/- 30V. ENVIRONMENTAL OPERATING CONDITIONS The instrument is designed for indoor use only under the following environmental conditions: Altitude...

  • Page 9: Accessories

    SPECIFICATIONS ACCESSORIES Standard Accessories Needle Probes ACC152 950 Plane Probe/Clip assembly ACC113 950 Current Trace Probe assembly ACC114 950 Stimulus Lead (Set of 4) ACC134 Lightweight Headphones EPM115 Optional Accessories Bare-board Stimulus Lead set (0.025") ACC121/XG25 Bare-board Stimulus Lead set (0.031") ACC121/XG31 Bare-board Stimulus Lead set (0.040") ACC121/XG40...

  • Page 10: Table Of Contents

    TONEOHM 950 operating modes......................1-1 SECTION 2 – INSTALLATION AND SET UP...................2-1 PREPARATION FOR USE ........................2-1 2.1 Unpacking............................2-1 2.2 Connecting the TONEOHM 950 to a power supply ..............2-1 2.3 Self test ............................2-2 SECTION 3 – DESCRIPTION ........................3-1 3.1 Connectors and probes .......................3-1 Plane Probe ..........................3-1...
  • Page 11 CONTENTS 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...
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  • Page 13: Section 1 Introduction

    Different methods are required to locate different types of short. TONEOHM 950 operating modes The TONEOHM 950 has five operating modes to enable the user to physically locate any type of short circuit without lifting components, cutting tracks or otherwise damaging the board under test: Track Resistance Milliohmmeter for locating low resistance shorts.
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  • Page 15: Section 2 - Installation And Set Up

    Unpacking The instrument is shipped in a sturdy transit pack. Open the pack carefully and remove the instrument and its accessories. The TONEOHM 950 carton should contain the following: TONEOHM 950 Needle probes Current Trace Probe / Drive Source lead assembly...

  • Page 16: Self Test

    GREEN GROUND Check that the TONEOHM 950 mains switch (on the rear panel) is OFF. Plug the power cable into the receptacle on the rear panel of the TONEOHM 950. Plug the other end into a wall outlet. Self test When the instrument is switched on it performs a self test.

  • Page 17: Section 3 - Description

    SECTION 3 – DESCRIPTION 3.1 Connectors and probes The instrument is supplied with three sets of probes. Each probe fits into a unique socket on the front panel. A LED adjacent to each socket indicates which probe to use in the selected range. Plane Probe The blue Plane Probe and Clip are used in the PLANE SHORTS range.

  • Page 18: 3.2 Indicators

    TONEOHM 950 OPERATOR MANUAL 3.2 Indicators Liquid crystal display The liquid crystal display (LCD) gives an indication of the parameter being measured in the units appropriate to the selected range. When TRACE, PLANE SHORTS or [Ω] is selected, the display is uncalibrated but proportional to the reading at the probes.

  • Page 19: 3.4 Ranges

    DESCRIPTION 3.4 Ranges Track Resistance There are five resistance ranges. A low resistance generates a high tone, and a high resistance generates a low tone. On the 200 mΩ range resistances below 15 mΩ generate a steady warble. Use the 200 mΩ and [Ω] ranges for locating low resistance shorts. These ranges are sensitive enough for measuring track resistance.
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  • Page 21: Section 4 - Operation

    SECTION 4 – OPERATION LOCATING FAULTS WITH THE TONEOHM 950 4.1 Range selection Different types of short circuit and loading fault require different location techniques. It is often possible to find the fault in more than one way, but the following approach is recommended. In some cases a combination of techniques may be required.

  • Page 22: 4.2 (Low Resistance) Shorts

    TONEOHM 950 OPERATOR MANUAL Table 4-1 indicates the suggested range for locating different types of short circuit. Type of fault Range Section Shorts below 200 mΩ [Ω], 200 mΩ Multi-layer shorts (static) PLANE SHORTS Multi-layer shorts (dynamic) 200mA Excessive Vcc loads...

  • Page 23: Plane Shorts

    OPERATION Moving the probe from B to C gives a higher reading and a lower tone, indicating that • the probe has moved beyond the fault. This implies that the fault is between B and C. • Now move the other probe from E to give the lowest reading and the highest •...

  • Page 24: Causes Of Shorts On Multi-Layer Boards

    Causes of Shorts on Multi-layer Boards Polar Instruments has evaluated many defective multi-layer boards (both bare and assembled) from a range of manufacturers and found that the cause of most of these faults are the same as on single or double-sided boards (e.g.

  • Page 25: Sensitivity Adjustment

    OPERATION If the warning bell sounds and the 950 returns to STANDBY, check that all the Plane • Stimulus leads are connected to the same plane. To protect components the maximum voltage appearing on the stimulus outputs is 500mV, and disconnecting any one of them will automatically turn the stimulus off and return to STANDBY.

  • Page 26: High Resistance Shorts

    Vcc pin of the IC. If this situation is suspected, try stimulating the Vcc plane instead of the ground plane. High Resistance Shorts When the resistance of the short is greater than 20–30 Ω then the TONEOHM 950 will not be able to resolve its position as precisely as for a "hard short".

  • Page 27: Multiple Shorts

    OPERATION Multiple Shorts If there are multiple shorts between planes, the Direction Arrows will not lead the operator to the short(s) and a different probing technique must be used as described in this section. To determine if multiple plane shorts are present, probe various points on the un- •...

  • Page 28: 4.4 Track Current Measurement

    Either power the board from its own supply, or disconnect external power and • connect the TONEOHM 950's Drive Source between the shorted nodes. Use of the Drive Source is recommended, as its output voltage is limited and its amplitude can be adjusted using the Drive Source control.
  • Page 29 OPERATION Positive current flowing through the track provides a tone and meter indication of the current flow. Negative current will produce a zero reading, no tone and the PROBES REVERSED LED will light. WRONG WRONG Figure 4-4 Track Current Probing Artisan Technology Group - Quality Instrumentation ...

  • Page 30: Excessive Vcc Loads

    TONEOHM 950 OPERATOR MANUAL Excessive Vcc Loads A common problem is a power supply rail being held low by a faulty device drawing excessive current. This is not a low resistance short (less than 200 mΩ) or the rail would read 0V and the shorts location procedure (Section 4.2) could be used.

  • Page 31: Example - Excessive Vcc Load

    OPERATION Example – Excessive Vcc Load Consider the board shown in Figure 4-5 where the Vcc supply is being loaded. Assume the fault is static. DRIVE SOURCE Figure 4-5 Excessive Vcc Load Connect the Drive Source leads across the Vcc and ground connections of the PCB. •...

  • Page 32: Example - Multiple Current Paths

    TONEOHM 950 OPERATOR MANUAL Example – Multiple Current Paths Often on power supply rails, there can be several paths from the Drive Source to the low resistance fault. As the current is not confined to one track, some interpretation is required.

  • Page 33: Current Tracing (Non-Contact)

    OPERATION 4.5 Current Tracing (non-contact) NOTE: Disconnect power from the board under test before using TRACE. Locating faults using TRACE This method is effective in the following situations: Densely populated double sided PCBs. • Environmentally coated PCBs. • Cable looms with internal shorts. •...

  • Page 34: Operation

    TONEOHM 950 OPERATOR MANUAL The DRIVE SOURCE LED indicates flow of Drive Source current. If the LED does not light, either the leads are connected incorrectly, or there may be insufficient current flowing for the Current Trace Probe to detect the resulting field.

  • Page 35: Bus Faults (Stuck Nodes)

    OPERATION DRIVE SOURCE Figure 4-7 Board Sectoring Connect the Drive Source Leads 10-20mm apart near one corner of the board • (Sector 3 in the illustration). Run the Trace Probe along the lines AB, then CD to determine if current is flowing •...

  • Page 36: Edge Connectors

    TONEOHM 950 OPERATOR MANUAL Connect the Drive Source leads across the faulty lines. • Adjust the Drive Source control so that the Trace Probe responds within 10mm of one • of the Drive Source leads. Pass the Probe over each suspect IC, with the thickest sides of the probe tip parallel •...

  • Page 37: Faulty Decoupling Capacitors

    OPERATION Adjust the Drive Source control to give a reading with the Current Trace Probe at edge connector height. Move the Probe down the gap between each connector in turn, starting nearest to the • Drive Source leads. As the Probe is moved between connectors 1 and 2, 2 and 3, 3 and 4, a tone is •...

  • Page 38: Track Voltage Measurement

    NOTE: Do not rely too much on voltage readings, or differences between readings, of less than 15µV. Readings as small as these can be caused by thermoelectric voltages instead of PCB track currents. For this reason the TONEOHM 950 does not produce a tone for readings below about 50µV. 4-18...

  • Page 39: Example - Excessive Vcc Loads

    OPERATION Example – Excessive Vcc Loads See Section 4.5 for a preferred method of tracing current. However, if the PCB tracks are very thick (i.e. very low resistance) then the following method is applicable. Consider the board shown in Figure 4-10 where the Vcc supply is being loaded. Assume the fault is static.
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  • Page 41: Section 5 - Maintenance And Cleaning

    SECTION 5 – MAINTENANCE AND CLEANING WARNING This instrument should only be serviced by a qualified electronics technician. Refer all servicing to qualified service personnel. Polar Instruments publishes a TONEOHM 950 Service Manual to assist the service technician. Calibration requirements To maintain the calibration of the instrument it is recommended that its Calibration/Adjustment Procedure is carried out at intervals not exceeding 12 months.
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  • Page 43: Section 6 - Application Note

    SECTION 6 – APPLICATION NOTE QUESTION ABOUT PLANE SHORTS For full details on using the PLANE SHORTS range refer to Section 4.3. Even if I can find the location of a short on a multi-layer board, will I be able to repair it? Most shorts on multi-layer boards have similar causes to those on single or double-sided boards —...
  • Page 44 TONEOHM 950 OPERATOR MANUAL What are the symptoms of multiple shorts? If the results of probing the stimulated plane are inconclusive, try probing the un-stimulated plane. If varying readings greater than 5.0 are obtained, this suggests that there are multiple shorts between the planes.
  • Page 45 Artisan Technology Group is your source for quality FAST SHIPPING AND DELIVERY Experienced engineers and technicians on staff Sell your excess, underutilized, and idle used equipment at our full-service, in-house repair center We also offer credit for buy-backs and trade-ins TENS OF THOUSANDS OF www.artisantg.com/WeBuyEquipment View...

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