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Polar Instruments TONEOHM 950 Service Manual

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Polar Instruments TONEOHM 950 Service Manual

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  • Page 2 Polar Instruments Ltd. Garenne Park St. Sampson TONEOHM 950 Guernsey SERVICE Channel Islands GY2 4AF MANUAL ENGLAND http://www.polar.co.uk Fax: +44 (0)1481 252476 Email: mail@polar.co.uk MAN130–2011...
  • Page 4 TONEOHM 950 SERVICE 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 6: Declarations

    DECLARATIONS DECLARATIONS European Community Directive Conformance Statement Refer to the Operator Manual to determine conformance with European Community Directives.

  • Page 7: Safety

    TONEOHM 950 SERVICE MANUAL SAFETY WARNING The service instructions contained in this manual are for use by qualified electronic service personnel only. WARNING The LIVE and NEUTRAL lines on this unit are BOTH fused. When the unit is connected to its supply, the opening of covers or removal of panels is likely to expose dangerous voltages.

  • Page 8: Operation

    The unit is designed for use indoors in an electrical workshop environment at a stable work station comprising a bench or similar work surface. Use only the accessories (e.g. test probes and clips) provided by Polar Instruments. The instrument must be maintained and repaired by a skilled electronics technician in accordance with the manufacturer’s instructions.

  • Page 9: Specifications

    TONEOHM 950 SERVICE MANUAL 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.

  • Page 10: Environmental Operating Conditions

    SPECIFICATIONS Drive Source 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 Up to 2000m Temperature +5°...

  • Page 11: Symbols

    TONEOHM 950 SERVICE MANUAL SYMBOLS REFER TO MANUAL These sockets are for connecting only Polar Instruments probes and connectors for use as described in the Operator Manual. To prevent damage to this product and to ensure its safe use observe the specifications given in this manual when connecting to terminals marked with this symbol.

  • Page 12: Table Of Contents

    Current offset calibration — Version 8 firmware and above............... 2-2 Current Trace ............................. 2-2 Plane Shorts ............................2-3 SECTION 3 – CIRCUIT DESCRIPTION....................3-1 TONEOHM 950 THEORY OF OPERATION..................3-1 Main Operating modes........................3-2 Track resistance ..........................3-2 Track Current ..........................3-2 Trace ..............................
  • Page 13 TONEOHM 950 SERVICE MANUAL Plane Shorts ........................... 3-2 Detailed Theory of operation......................3-3 Microvolt Amplifier .......................... 3-3 Trace Amplifier ..........................3-3 Current Source ..........................3-3 Plane Amplifier and Vector Discriminator..................3-3 Vectored Plane Stimulus ........................ 3-4 Drive Source........................... 3-5 Tone Generator ..........................

  • Page 14: Section 1 Performance Check

    SECTION 1 PERFORMANCE CHECK MAINTENANCE AND CALIBRATION OF INSTRUMENTS For most of Polar Instruments’ products there are two maintenance procedures — the Performance Check and the Calibration. Some instruments may have a single (combined) procedure. Performance Check The Performance Check (or Checkout Procedure) is used to verify the basic functions of the instrument.

  • Page 15: Performance Check

    TONEOHM 950 SERVICE MANUAL PERFORMANCE CHECK Equipment required • DC voltage source, variable from 1V to 10V and accurate to 0.1%. • High tolerance resistors (0.5%) of the following values: 10KΩ, 1KΩ (serial numbers below 005975 only), 200Ω, 100Ω, 1Ω and 0.1Ω.
  • Page 16 PERFORMANCE CHECK 20. Slowly turn the DRIVE SOURCE from minimum to maximum (i.e. clockwise). As the control is rotated, check that initially all direction arrow LEDs are on, then the upper LED only, then all LEDs are off. At the same time the tone goes from high to low then off.

  • Page 18: Section 2 - Adjustment Procedure

    SECTION 2 – ADJUSTMENT PROCEDURE ADJUSTMENT PROCEDURE WARNING: Hazardous voltages are exposed on the PCB when the cover is removed. This procedure should only be performed by a technically qualified person aware of the hazards and taking all reasonable care. Equipment required •...

  • Page 19: Current Range Adjustment

    TONEOHM 950 SERVICE MANUAL Current range adjustment (Serial Nº. 012213 and above — below this Serial Nº. there is no adjustment.) 1. Select the 200mA range. Drive source control fully clockwise. 2. Connect the drive source and the DVM across the high tolerance 1Ω resistor.

  • Page 20: Plane Shorts

    ADJUSTMENT PROCEDURE Plane Shorts 1. CONNECT the 4 Plane Stimulus leads BLUE to YELLOW and RED to GREEN 2. Push PLANE twice to enter ACTIVE mode. 3. CONNECT the Plane Clip to the Plane Probe. Adjust R85 for a reading of 00.0 ± 3 counts.

  • Page 22: Section 3 - Circuit Description

    SECTION 3 – CIRCUIT DESCRIPTION TONEOHM 950 THEORY OF OPERATION. The TONEOHM 950 consists of the following functional blocks. 1. Microvolt Amplifier Amplifies/attenuates PCB track voltages, and is used in conjunction with the internal current source for the calculation of track resistance and current.

  • Page 23: Main Operating Modes

    TONEOHM 950 SERVICE MANUAL Main Operating modes. Track resistance Current is injected into the track with the needle probes using the CURRENT SOURCE module, the µV AMPLIFIER conditions the resulting track voltage and displays the result directly on the LCD.

  • Page 24: Detailed Theory Of Operation

    CIRCUIT DESCRIPTION Detailed Theory of operation. Microvolt Amplifier JP11 is the input connection from the probe sockets. Relays K1, 2 and 3 provide ÷ 1, ÷ 10 and ÷ 1000 attenuation setting for the main Amplifier U1. K4 provides a switchable 120Ω input resistance used in 2mV and 20mV.

  • Page 25: Vectored Plane Stimulus

    TONEOHM 950 SERVICE MANUAL The 950 extracts this information as follows: U12 Amplifies the low level signal from the Plane Probe; this chopper-stabilised amplifier is clocked by a signal synchronous with the Vectored Stimulus to minimise clock noise on the a.c. output signal. JP12 connects to the Drive Source/Sensitivity control to allow user adjustment of sensitivity.

  • Page 26: Drive Source

    CIRCUIT DESCRIPTION In order to protect semiconductor devices, D30 and D34 are Schottky diodes which conduct if the stimulus voltage attempts to rise above approximately 0.4 volts. This will occur if the stimulus is not connected correctly. As D30 or D34 conduct, current no longer flows through L1 or L2, the microprocessor registers NO_PLANE_DS and turns off K14.

  • Page 27: Microprocessor

    TONEOHM 950 SERVICE MANUAL Note that from Serial Nº. 011265 a line filter was fitted and the line voltage selector switch was replaced by links. The power transformer has undergone several changes — check the REPLACEMENT PARTS list before ordering spares.

  • Page 28: Section 4 - Dismantling Instructions

    SECTION 4 – DISMANTLING INSTRUCTIONS WARNING Service of this instrument should only be performed by skilled electronics service personnel. There are hazardous voltages inside the instrument when connected to its power supply. REMOVE THE POWER CORD before touching any part of the line input circuit. Note that high voltages may continue to be present for 2 minutes after power is removed until internal capacitors discharge.

  • Page 30: Section 5 - Line Voltage And Fuse Changing

    SECTION 5 – LINE VOLTAGE AND FUSE CHANGING WARNING Service of this instrument should only be performed by skilled electronics service personnel. There are hazardous voltages inside the instrument when connected to its power supply. REMOVE THE POWER CORD before touching any part of the line input circuit. Note that high voltages may continue to be present for 2 minutes after power is removed until internal capacitors discharge.

  • Page 32: Section 6- Fault Diagnosis

    SECTION 6– FAULT DIAGNOSIS WARNING Service of this instrument should only be performed by skilled electronics service personnel. Hazardous voltages are exposed on the PCB when the cover is removed. These procedures should only be performed by a technically qualified person aware of the hazards and taking all reasonable care.

  • Page 34: Section 7 - Maintenance And Cleaning

    If it becomes necessary to repair the instrument, in the first instance contact the Polar Instruments distributor in your country. In case of difficulty contact Polar Instruments Ltd. at the address at the front of this manual. Do not send the instrument until shipping instructions have been received from the...

  • Page 36: Section 8 - Replacement Parts

    Note: Parts marked with an asterisk (*) have been subject to modification in later instruments. Safety critical parts (listed in bold type) must be replaced with parts obtained from Polar Instruments Ltd or your Polar Instruments distributor to ensure continued safe operation.

  • Page 37: Front Panel Kit

    TONEOHM 950 SERVICE MANUAL FRONT PANEL KIT Part Nº Description CircuitReference CEA103 10µF Electrolytic C57, C66, C68 CVD101 0.1µF Polyester CVD102 0.01µF Polyester CVD105 0.22µF Polyester C58, C59 CVD116 100pF Ceramic CVD136 0.1µF Mini Ceramic C67, C69 CVD154 * Polyester...

  • Page 38: Main Board Kit

    REPLACEMENT PARTS MAIN BOARD KIT Part Nº Description CircuitReference CEA103 10µF Electrolytic C4, C5, C29, C41, C49, C50, C52, C53, C71, C75*, C78*, C82 CEA105 220µF Electrolytic CEA117 2,200µF Electrolytic C40, C43, C45, C46 CEA122 1µF 63V Electrolytic C75*, C79* CVD101 0.1µF Polyester...
  • Page 39 TONEOHM 950 SERVICE MANUAL ICA166 CD74HC74E ICA173 MC74HC04N ICA186 TL084CN (or LF347N) U2, U9 ICA187 LM386N-1 ICA188 ICA189 TL 7705 ICA190 74HC138 U37, U43 ICA191 74HC08 ICA192 74HC374 U28, U39, U40, U46, U47, U63 ICA195 74HC32 ICA198 74HC245 ICA208 74HCT373...
  • Page 40 REPLACEMENT PARTS RCF10K R12, R29, R31*, R63, R64, R74, R75, R86, R88, R89, R112, R124, R127, R147, R155, R171, R207, R208, R209, R256, R260, R265, R279, R281, R282, R717 RCF10M R251 RCF10R R174, R714 RCF150K 150K R2, R244 RCF15K R28* RCF1K0 R15, R16, R18, R21, R23, R92, R100, R109, R129, R201, R206,...
  • Page 41 TONEOHM 950 SERVICE MANUAL RCT1K 1/4W RCT1M0 1/4W R46, R54, R56 RCT1R0 1/4W R36, R43, R284 RCT200R 200R 1/4W R203 RCT20K 1/4W R11, R96 RCT220K 220K 1/4W RCT24K 1/4W RCT2K0 1/4W R10, R159, 5160 RCT430K 430K 1/4W R204 RCT470K 470K...

  • Page 42: Mechanical Kit

    REPLACEMENT PARTS MECHANICAL KIT 0Part Nº Description CircuitReference CVD155 * 470pF Polypropylene C709, C710, C711, C712, C713 EPM111 Loudspeaker FCA112 Fuse 250mA T F5*, F6* 115V FCA119 Fuse 125mA T F5*, F6* 230V FCA121 Fuse 160mA T F5*,F6* 230V FCA122 Fuse 315mA T F5*,F6* 115V IND107 *...
  • Page 43 TONEOHM 950 SERVICE MANUAL WMA197 Speaker Lead WMA202* Plane Cable Blue WMA305* Plane Drive Cable...

  • Page 44: Section 9 - Schematic Diagrams

    REPLACEMENT PARTS SECTION 9 – SCHEMATIC DIAGRAMS...
  • Page 45 TONEOHM 950 SERVICE MANUAL This page is intentionally blank.
  • Page 46 +5UREG USES 4053 ON TONE GENERATOR DIAGRAM U62A TL082 L272 R272 R273 1M 1% 100K 1% .22u 270pF MJE350 R713 05 Boards and later used 56mV 1N4007 on 970 .1u 400V Ohms Adjust .56V 100K R712 U62B R287 R275 200R L272 R276 R277...
  • Page 47 C706 DMM_HI PLANEV+ DMM_LO Trace+ R158 TRACE- 100K 4052 R289 R161 MODE_0 MODE_1 R290 REF- 100K TL084 REF IN- STATUS BUSY C34 1uF REF CAP- DACV+ REF CAP+ REF+ REF IN+ D[0..7] D[0..7] .01u IN HI IN LO COMMON R159 REF25Z R203 2K0 1%...
  • Page 48 +5UREG USES 4053 ON TONE GENERATOR DIAGRAM 100K 1% 1M 1% U62A TL082 L272 R272 R273 .56V 56mV 1M 1% 100K 1% .22u 270pF MJE350 R713 05 Boards and later Ohms Adjust Current 56mV 1N4007 To U5A Pin 3 .1u 400V Ohms Adjust .56V 100K...
  • Page 49 +12V DS +5V DS R104 2N3906 U13A To front panel connector +5V DS R123 R102 DS_POT1 68R 2W R105 LM339 113K 1% DS_POT2 R100 .1uF R112 R106 20K 1% PIN 3 OF POT TO 0V DS 2N3904 U13B 0V DS 1N4148 CA3140 0V DS...
  • Page 50 +12V DS +5V DS R104 2N3906 U13A +5V DS To front panel connector R123 R102 68R 2W DS_POT1 R105 LM339 113K 1% PIN 3 OF POT TO 0V DS R100 .1uF DS_POT2 R112 R106 20K 1% 2N3904 U13B 0V DS 1N4148 CA3140 0V DS...
  • Page 51 PLANE Headphones L701 10uH HEADER3 VPLANE+ R710 82ZA2 VSHORT C709 C710 470pF 470pF Track DS / Current Probe Trace NEEDLE HEADER10 PROBES Kelvin+ Probe+ Probe- C712 Kelvin - C713 C711 470pF 470pF 470pF R705 82ZA2 Polar Intruments Ltd Garenne Park, St. Sampsons Guernsey, Channel Islands Inst.
  • Page 52 A[0..15] A[0..15] A[0..15] A[0..15] D[0..7] D[0..7] D[0..7] D[0..7] D[0..7] Z80A D[0..7] DS_POT1 /MREQ MREQ QUADRANT_1 IORQ ARROW_OFF 8-3K3 BD[0..7] BD[0..7] REFSH A[0..15] HALT WAIT 6116 RESET BUSRQ QUADRANT_0 8-22K BUSAK CS31 27256 CS33 DS_POT2 0V DS CS32 VOLUME_POT2 R171 A[0..15] CS34 REVERSED A[0..15]...
  • Page 53 D9 1N4148 D10 1N4148 D11 1N4148 10uF JP13 1N4148 0V DS R19 4K7 .01uF TL084 .022uF JP11 100K .1uF TL084 Trace+ 1N4148 TL084 TL084 R297 100K .1uF 10uF .1uF Trace- VSHORT PLANE+ RELAY K1 connected this way for thermal match I_SOURCE 100K C708...
  • Page 54 R715 Fitted from S/No 012213 R717 SAMPLE R251 1M 1% R716 74HC04 PHASE C703 R252 C714 0.1uF R714 GUARD R209 10K 1% 100K GUARD PLANE+ CLAMP 100K 1% TLC279 DIODE DIODE R236 1K JP12 R292 100K 1% INT/EXT 0.01 CLK OUT 10K 1% 1N4148 TLC279...
  • Page 55 U21A NO_TONE R206 U23C 4016 R134 R147 4013 R207 R144 R143 R148 10uF LF353 270R 1N4148 U21B Pin7 to -5A R151 R279 U20D Invert ON for uV R135 R157 22K R278 R145 LM339 4013 R136 10RET .01uF Pin7 to -5A R149 R137 .56V...
  • Page 56 BD[0..7] BD[0..7] Sensitivity 74HC374 R191A OHMS R174 270R 20mOHMS R175 270R 100K Ganged 2OHMS DS_POT2 VOLUME_POT1 R176 270R 2KOHMS R177 270R Volume 20KOHMS R178 270R R192 TRACE 100K Panel R184 270R R700 QUADRANT_0 ARROW_OFF QUADRANT_1 330R DS_POT2 DS_POT1 VOLUME_POT1 DS_POT3 VOLUME_POT2 NO_TRACK_DS D[0..7]...
  • Page 57 BD[0..7] BD[0..7] Sensitivity 74HC374 R191A OHMS R174 270R 20mOHMS R175 270R 100K Ganged 2OHMS DS_POT2 VOLUME_POT1 R176 270R 2KOHMS R177 270R Volume 20KOHMS R178 270R 200mA R192 R179 270R R181 270R 100K Panel TRACE R180 270R R700 QUADRANT_0 ARROW_OFF QUADRANT_1 330R DS_POT2 DS_POT1...
  • Page 58 R227 R231 R228 R229 R230 R232 R233 BACKLIGHT ARRAY .22uF R226 C59 .22uF DMM_LO BUFF C700 IN LO .1uF R194 IN HI DMM_HI COMMON C- REF C701 C+ REF R196 REF LO REF HI .01uF TEST OSC3 OSC2 OSC1 R197 Volts Cal 7106 R195...
  • Page 59 R715 Fitted from S/No 012213 R717 SAMPLE R251 1M 1% R716 74HC04 PHASE C703 R252 C714 0.1uF R714 GUARD R209 10K 1% 100K GUARD PLANE+ CLAMP 100K 1% TLC279 DIODE DIODE R236 1K JP12 R292 100K 1% INT/EXT 0.01 CLK OUT 10K 1% 1N4148 TLC279...

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