Fluke 77 Series III, Service Manual

Page 1: ...7 Series III Multimeter Service Manual PN 800604 November 1998 Rev 1 11 99 1998 1999 Fluke Corporation All rights reserved Printed in U S A All product names are trademarks of their respective compani...

Page 2: ...3 Detailed Description 2 3 2 4 Voltage Signal Conditioning 2 3 2 5 Current Conditioning 2 4 2 6 Ohms 2 4 2 7 Additional Circuitry 2 4 2 8 AC Converter 2 5 2 9 Active Filter 2 5 2 10 Rotary Switch 2 5...

Page 3: ...cking the Crystal Oscillator 3 13 3 17 Checking The Reference Voltage 3 13 3 18 Checking Display Drive Voltage 3 13 3 19 Checking Beeper Drive Signal 3 13 3 20 Tracing the VDC Signal Path 3 13 4 List...

Page 4: ...ions 1 5 2 1 S1 Function Codes 2 6 3 1 Recommended Test Equipment 3 3 3 2 DC Voltage Test 3 8 3 3 AC Voltage Test 3 8 3 4 Resistance Test 3 10 3 5 DC mA Test 3 11 3 6 DC Amps Test 3 11 4 1 Final Assem...

Page 5: ...77 Series III Service Manual iv...

Page 6: ...v List of Figures Figure Title Page 2 1 Overview 2 3 2 2 AC and A D Converter 2 7 3 1 Assembly Details 3 6 3 2 Troubleshooting Tree 3 12 4 2 A1 Main PCA 4 9 5 1 A1 Main PCA 5 4...

Page 7: ...77 Series III Service Manual vi...

Page 8: ...rty Never use the meter if the meter or test leads look damaged Always turn off power to the circuit before cutting unsoldering or breaking the circuit Small amounts of current can be dangerous Never...

Page 9: ...rating as specified on the case bottom fuse rating label Do Not Remove Cover Always operate the meter with case top and bottom properly assembled Access procedures and the warnings for such procedures...

Page 10: ...1 1 Chapter 1 Introduction and Specifications Contents Page 1 1 Introduction 1 3 1 2 Organization of the Service Manual 1 3 1 3 Conventions 1 4 1 4 Specifications 1 4...

Page 11: ...77 Series III Service Manual 1 2...

Page 12: ...d Specifications This chapter describes use of the Service Manual and application of special terminology conventions to describe the meter s circuitry A complete set of specifications appears at the e...

Page 13: ...attached parts Circuit Nodes Individual pins or connections on a component are specified by a dash following the component reference designator For example pin 19 of U30 would be U30 19 User Notation...

Page 14: ...y Specified accuracy 0 1 of range Relative Humidity except 32 M range 32 M range only 0 to 90 0 C to 35 C 0 to 70 35 C to 50 C 0 to 80 0 C to 35 C 0 to 70 35 C to 50 C Altitude Operating 2000 meters S...

Page 15: ...Other ranges 45 to 1 kHz 3 200 V 32 00 V 320 0 V 1000 V 2 2 2 2 2 2 2 2 e 320 0 3200 32 00 k 320 0 k 3 200 M 32 00 M 0 5 3 0 5 1 0 5 1 0 5 1 0 5 1 2 0 1 G R 2 0 V 1 typical Function Range Accuracy Bur...

Page 16: ...de Rejection L mL 120 dB at dc 50 Hz or 60 Hz 60 dB at 50 Hz or 60 Hz K 60 dB dc to 60 Hz Open Circuit Test Voltage Full Scale Voltage To 3 2 M 32 M e 3 1 V dc 2 8 V dc typical 440 mV dc 420 mV dc typ...

Page 17: ...77 Series III Service Manual 1 8...

Page 18: ...3 2 2 Functional Block Description 2 3 2 3 Detailed Description 2 3 2 4 Voltage Signal Conditioning 2 3 2 5 Current Conditioning 2 4 2 6 Ohms 2 4 2 7 Additional Circuitry 2 4 2 8 AC Converter 2 4 2 9...

Page 19: ...77 Series III Service Manual 2 2...

Page 20: ...1 OHMS 3 0 0 m V DCV A C V OFF ACmV D C m V A D J1 Input Signal Conditioning Range and Function Control To Bar Graph To Digital Display LCD S1 U2 Microcomputer A D Samples Y1 32 768 kHz Counter U1 Ana...

Page 21: ...nt R5 and R13 act as a voltage divider for the 300 mA range F1 protects the mA circuitry F3 protects the 10A circuitry 2 6 Ohms When the ohms function is selected the meter compares the unknown resist...

Page 22: ...T selects and routes the input signals Function codes for switch S1 REAR are shown in Table 2 1 Range switch S2 signals the microcomputer U2 for the manual ranging and automatic Touch Hold function CR...

Page 23: ...sistors of Z1 between pins 8 9 and 10 C8 is the integrator capacitor A series of 10 minor cycle conversions occurs without taking time for an autozero phase between the conversions These minor cycle c...

Page 24: ...C AC AC AC FILTER FILTER R10 C11 C5 C6 C8 C7 C9 R18 R19 R17 R9 16 17 28 26 39 40 27 44 45 10 9 8 46 47 INPUT DIGITAL SECTION Z1 Z1 INT DE INT REF REF AC CONVERTER ACTIVE FILTER BUFFER INTEGRATOR COMPA...

Page 25: ...77 Series III Service Manual 2 8...

Page 26: ...3 7 3 8 AC Voltage Test 3 8 3 9 Resistance Test 3 8 3 10 Diode Test 3 9 3 11 DC mA Test 3 10 3 12 DC Amps Test 3 11 3 13 Calibration 3 11 3 14 Troubleshooting 3 11 3 15 Supplemental Troubleshooting Pr...

Page 27: ...77 Series III Service Manual 3 2...

Page 28: ...quipment required for the performance tests and calibration is listed in Table 3 1 If the recommended equipment is not available instruments with equivalent specifications may be used Table 3 1 Recomm...

Page 29: ...s from the back side of the pca 2 Remove the LCD mounting bracket 3 Insert a small screwdriver under the edges of the display holding bracket and gently pry the bracket loose from the snaps 4 Turn the...

Page 30: ...gent and water The pca may be washed with isopropyl alcohol or deionized water and a soft brush Remove the display assembly and fuses before washing and avoid washing the switch if possible Dry the pc...

Page 31: ...eric Connector Internal Cover Shaft Adapter AC Shield Main PCA Screw 4 14 Bottom Shield Case Bottom Assembly Screw 5 14 Probe Holder Tilt Stand Knob Assembly Shock Absorber Detent Spring Key Pad Screw...

Page 32: ...the rating shown on the back of the meter Warning To avoid false readings which could lead to possible electric shock or personal injury replace the battery as soon as the battery indicator N appears...

Page 33: ...e Calibrator for the output given in Table 3 3 verify that the UUT display reading is within the limits shown Note When the input is open in the VAC function it is normal for the meter to read some co...

Page 34: ...n 3 10 Diode Test 1 Set the UUT to the Diode Test function Note On Fluke 5100 series calibrators activate the 50 divider override On Fluke 5500A calibrators lock voltage to the 33V range 2 Apply an in...

Page 35: ...1911 4 19 k 18 89 to 19 11 k 5 190 k 188 9 to 191 1 k 6 1 9 M 1 889 to 1 9111 M 7 19 M 18 61 to 19 39 M Decades of 2 7 2 270 268 3 to 271 7 plus 0 reading 3 2 7 k 2685 to 2715 4 27 k 26 85 to 27 15 k...

Page 36: ...cover as previously described 3 Connect the DC Voltage Calibrator to the zand COM input terminals of the UUT 4 Set the DC Voltage Calibrator for an output of 3 000V dc and adjust R8 for a display rea...

Page 37: ...nd R12 for 1 6V dc Switch meter to V and apply 3V dc Does meter display 3 VDC 4 ON YES Probable cause a RV1 or RV2 or RV3 shorted b S1 Contacts bad c Z1 open or out of tolerance d U1 bad e U1 loose sh...

Page 38: ...e related failures include R11 or R12 3 19 Checking Beeper Drive Signal Put the unit in the Diode Test Mode and short the input leads Using an oscilloscope measure the signal at pin 3 of U1 The signal...

Page 39: ...77 Series III Service Manual 3 14...

Page 40: ...elines for handling them 3 Using the procedures packaging and bench techniques that are recommended The following practices should be followed to minimize damage to S S static sensitive devices 1 MINI...

Page 41: ...CONDUCTIVE EDGES AND NEVER TOUCH OPEN EDGE CONNECTOR EXCEPT AT STATIC FREE WORK STATION PLACING SHORTING STRIPS ON EDGE CONNECTOR HELPS PROTECT INSTALLED S S DEVICES 9 HANDLE S S DEVICES ONLY AT A STA...

Page 42: ...Chapter 4 List of Replaceable Parts Contents Page 4 1 Introduction 4 3 4 2 How to Obtain Parts 4 3 4 3 Newer Instruments 4 3 4 4 Service Centers 4 3 4 5 Manual Status Information 4 4 4 6 Parts Lists...

Page 43: ...77 Series III Service Manual 4 2...

Page 44: ...stallation instructions if necessary To ensure prompt delivery of the correct part include the following information when you place an order Part number and revision level of the pca containing the pa...

Page 45: ...the location of each part and its reference designator The parts lists give the following information Reference designator An indication if the part is subject to damage by static discharge Descripti...

Page 46: ...991 1 MP4 HOLDER PROBE 648748 1 MP5 STAND TILT 648961 1 MP6 LABEL WINDOW 844337 1 MP9 SHIELD AC 648755 1 MP10 SPRING DETENT 822643 4 MP11 KNOB SWITCH 648706 1 MP12 ADAPTER SHAFT 649175 MP14 CASE BOTTO...

Page 47: ...77 Series III Service Manual 4 6 MP6 MP17 MP18 MP20 DS1 MP21 MP19 MP12 MP9 A1 H2 MP23 MP14 H7 MP4 MP5 MP11 MP16 MP10 S2 H1 F1 F2 BT1 MP40 LS1 FLUKE 77 3 aaa05c eps Figure 4 1 Final Assembly...

Page 48: ...NPN 60V 350MW SOT 23 742676 1 R1 RES WW 3 5K 5 5W 20PPM 107695 1 R2 RES CERM 1K 5 1W 200PPM 601176 1 R3 RES CERM 1M 5 1W 655175 1 R4 RES CF 100K 1 0 25W 100PPM 769802 1 R5 RES MF 402K 0 25 0 25W 50PP...

Page 49: ...Manual 4 8 Table 4 2 A1 Main PCA cont Ref Des Description PN Qty Notes XF2 CONTACT FUSE 707190 2 Y1 CRYSTAL 32 768KHZ 1 3 X 8MM 643031 1 Z1 RNET CERM SIP FLUKE 77 HI V DIV 946202 1 Z2 RNET CERM SIP H...

Page 50: ...List of Replaceable Parts Parts Lists 4 4 9 FLUKE 77 3 4001 aaa06f eps Figure 4 2 A1 Main PCA...

Page 51: ...77 Series III Service Manual 4 10 FLUKE 77 3 4001 aaa07f eps Figure 4 2 A1 Main PCA cont...

Page 52: ...5 1 Chapter 5 Schematic Diagrams...

Page 53: ...77 Series III Service Manual 5 2...

Page 54: ...uto Zero Point BPR Beeper Driver BT Battery CLK Clock Output COM Common DCS DC Sense EC Reference Voltage FA0 Active Filter Amp Output FA Active Filter Amp Feedback INT Integrator Oputput K0 Buffer x...

Page 55: ...77 Series III Service Manual 5 4 FLUKE 77 3 4001 aaa06f eps Figure 5 1 A1 Main PCA...

Page 56: ...Schematic Diagrams 5 5 5 FLUKE 77 3 4001 aaa07f eps Figure A1 Main PCA cont...

Page 57: ...44 8K R3 1 0M RT1 1 1K C1 0 01 S1 R4 100K 33PF C14 R2 1 0K RV3 910V NOT USED USED LAST REFERENCE DESIGNATON Z2 Y1 VR1 U2 TP2 TP3 S3 RV3 RT1 R2 R19 Q3 LS1 J4 F2 DS1 CR2 C15 BT1 VAC VDC OHMS VDC MVDC OH...

Page 58: ...ER INTEGRATOR TO DIGITAL SECTION COMPARATOR BUFFER D3 D2 D1 D0 C0 NDAV CLK C1 C2 C3 EC OHMS DE INT DE INT AP75 U1 47PF C16 TP1 10 C9 9 20K R18 32 768KHZ Y1 47PF C12 33PF C15 027 C6 20 5K R17 027 C5 R1...

Page 59: ...TES MYLAR POLYESTER FILM CAPACITOR CERM DESIGNATES CERMET FILM RESISTOR MF DESIGNATES METAL FILM RESISTOR MG DESIGNATES METAL GLAZE RESISTOR WW DESIGNATES WIRE WOUND RESISTOR TA DESIGNATES TANTALUM CA...