Megger MIT510 User manual

MIT510, MIT520, MIT1020,
S1-552, S1-554, S1-1052 S1-1054
High Voltage Insulation Testers.
Issue 2
Date 17/08/06
COPYRIGHT © MEGGER LIMITED
6172-999

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MIT5XX/10XX
1st Used On:
SERVICE MANUAL
Contents Page
Section 1 Safety Warnings and Hazards. 3
Section 2 Instrument Assembly and Disassembly. 4
Section 3 Battery charge calibration. 11
Section 4 Circuit Description Block Diagrams. 13
Section 5 Circuit Diagrams 20
Section 6 Component Layouts 57
Section7 BOM’s 66
Section 8 Test and Calibration Specs. 80
Appendix 1 Common Faults. 81
Appendix 2. Firmware Error Codes. 82
Appendix 3 Firmware Updates. 83
Appendix 4 Spare Parts List. 84

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SERVICE MANUAL
Section1 Safety Warnings and Hazards.
Warning: These instruments generate high voltages. The MIT510 and MIT520 are 5kV insulation testers. The
MIT1020 is a 10kV instrument. Only trained and qualified persons should service this product after a risk
assessment.
The copyright to this document is owned by Megger Ltd. This document must not be copied or reproduced in whole
or part without the prior written consent of the copyright owner.

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The insulation tester models differ in the following ways:
a. The MIT520 has ‘USB’ capability and additional keys for added functionality.
b. The MIT1020 has ‘USB’ capability and a different ‘HV’ Board from the ‘5 series’ models. It also has
additional keys for the added functionality.
c. The S1-552 and S1-554 are the same build as the MIT520 and MIT1020 respectively, but provide a
higher output current (selected in firmware).
d. The S1-554 and S1-1054 are the same build as S1-552 and S1-1052 respectively, but are fitted with
a different measurement board to provide increased noise current filtering. Additional filtering menus
are also available in the firmware
Section 2 Instrument Assembly and Disassembly. Page
2.1 MIT510/520 & 1020 Assembly. 5
2.2 MIT510/520 & 1020 Disassembly. 6
2.3 MIT510/520 & 1020 Assembly Numbers 6
2.4 MIT510/520 & 1020 Drawings. 8
2.5 Interconnect Diagrams. 10

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SERVICE MANUAL
MIT Assembly. (Refer to Assembly Drawings)
2.1 Front Panel assembly.
1. Fit springs to high voltage shutter sockets and locate into recess of raised socket moulding guides.
2. Screw down shutter cover over shutter sockets.
3. Locate and screw down Power board into case bosses.
4. Locate Serial board into boss slots.
5. Screw down one fixing plate (nearest shutter cover) to hold one side of board in place.
6. Snap fit ‘IEC’ socket into front panel. Solder wires of ferrite/3 way Molex (see WACL 6140-388) assembly to ‘IEC’ socket.
Connect 3 way Molex socket to Power board.
7. Secure ‘tywraps’ to ferrite and screw down via second fixing plate onto other Serial board boss slot.
8. Place Perspex window into front panel recess.
9. Fit light pipes into front panel.
10. Locate rubber keypad moulding and affix onto front panel.
11. Locate and screw down Keyboard assembly into case bosses.
12. Locate and screw down Display board into case bosses.
13. Connect Power board to Display board, Serial board to Display board, Keyboard to Display board ribbon cables.
14. Affix to front panel; high voltage terminal indication label, mains input voltage limits label, and communication input/output
label.
15. Locate and fix plastic communications cover.
Module Housing Base and Module Housing Cover Assembly.
1. Locate and fix transformer assembly with cable tie.
2. Locate and screw down ‘Hv’ board into case bosses. Fit crimped ‘0v’ bond wires to tabs on ‘Hv’ board.
3. Place ‘Hv’ socket connector into housing cover terminal near communication recess. Place over bottom of connector a washer,
leakage spring, guard plate and socket mount. Secure these to cover terminal with 2 screws. Place crimp ring on brown wire
with ferrite (WACL 6140-388) onto bottom of connector and tighten on with washer and nut. Locate another ‘Hv’ socket into
next terminal socket through guard plate and secure crimped brown wire by tightening with washer and nut. Locate final ‘Hv’
socket into last housing cover terminal, place crimp ring on blue wire with ferrite (WACL 6140-388) onto bottom of connector,
fasten on with washer and nut.
4. Fit fuse to battery lead assembly (6180-454). Fit battery lead assembly to battery, fused lead fitted to positive terminal. Lower
battery into module base battery compartment, with battery positive terminal closest to base bottom; the battery terminals
facing the base module side.
5. Connect isolation transformer cable terminated in 2 way Molex to power board, connect the other crimped wires to matched
terminals on ‘Hv’ board. Connect battery cable to power board.
6. Connect Measurement board ribbon to ‘Hv’ board.
7. Locate and screw down measurement board onto ‘Hv’ board spacers.
8. Connect crimped wire between tab labelled ‘MB’ on Measurement board and ‘Hv’ board tab near where the isolation
transformer wires have been fitted to the ‘Hv’ board. Connect crimped ‘0v’ bond wires between Measurement board and ‘Hv’
board.
9. Fit blue wire on housing cover to ‘Hv’ board, shown as W5 on assembly drawing. Fit other brown wires on housing cover to
Measurement board. The middle brown wire on housing cover goes to tab screen printed ‘G’, and the other connects to tab
screen printed ‘Lo’.
10. Locate and fasten down module housing cover onto module base.
Fitting case together.
to Measurement board 13497-100
1. Locate and screw down front panel onto module base.
2. Slide case lid onto base module hinges.

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MIT5XX/10XX
1st Used On:
SERVICE MANUAL
2.2 Disassembly is reverse of assembly.
1. Unscrew front panel.
2. If the front panel is to be removed from the module housing base, disconnect the battery and isolation transformer cables from
the power board assembly, otherwise rest the front panel down beside the module housing case.
3. Unscrew the module housing cover. If the module housing is to be removed, pull off the three crimped wires screwed down on
the module housing cover from their respective tabs on the measurement and ‘HV’ board. Otherwise angle the module housing
cover towards the lid and rest it on the module base.
4. To remove the measurement board, remove all crimped wires attached to measurement board, disconnect ribbon going to ‘HV’
board and then unscrew the measurement board from ‘Hv’ board spacers. Remove measurement board.
5. To remove the ‘HV’ board disconnect the crimped wires from the isolation transformer and unscrew from case bosses. Remove
‘HV’ board.
6. To remove the isolation transformer, disconnect 2 way Molex connector from power board, cut mounting cable tie, and pull off
panel mounted cable tie securing ferrites.
7. To remove battery, disconnect battery cable to power board, and slide it out of the battery housing compartment.
8. To remove power board assembly, disconnect all cables left on the power board. Unscrew the board from front panel bosses.
9. To remove display board assembly, remove all ribbon, and unscrew the board from front panel bosses.
10. To remove keyboard, unscrew from front panel.
11. To move serial ‘coms’ board, unscrew fixing plates and slide board from boss guides.
2.3 Assembly Numbers.
MIT510 insulation tester 6411-093
MIT1020 insulation tester 6411-092
Mechanical Drawing Assembly PDF No. 6411-092
MIT510/1020 keyboard PCB 5240-432
MIT510/1020 power PCB 5240-431
MIT510 high voltage PCB 5240-430
MIT1020 high voltage PCB 5240-429
MIT510/1020 measurement PCB 5240-428
MIT510/1020 display PCB 5240-433
MIT510 serial interface PCB 5140-988
MIT520/1020 serial interface PCB 5140-987
Assembly Drawing List
6430-861 MIT510/1020 Display Board Assembly.
6231-756 MIT510 Serial Interface Board Assembly.
6231-758 MIT520/1020 Serial Interface Board Assembly.
6231-716 MIT510/1020 Key Board Assembly
6331-804 MIT510/1020 Power Board Assembly.
6430-865 MIT510/520 5kv Module Assembly.
6430-864 MIT1020 10kv Module Assembly.
6231-766 MIT510/1020 Isolation Transformer.
Cable Forms WACL 6140-388
Keyboard to Display board 30 way ribbon 13497-095
Power board to Display board 14 way ribbon 13497-100
Serial board to Display board 14 way ribbon 13497-100
HV board

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SERVICE MANUAL
2.4 Assembly Drawings.

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SERVICE MANUAL

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SERVICE MANUAL
2.5 Interconnect Diagram for MIT510/MIT520 models
Note: The W numbers shown on this diagram are not the same as W numbers on assembly drawings.
Note: The 520 Model uses serial board Assy 6231-758, Pcb 5140-987
Keyboard
Assy 6231-716
Pcb 5240-432
Display Board
Assy 6430-861
Pcb 5240-433 Serial Board
Assy 6231-756
Pcb 5140-988
Power Board
Assy 6331-804
Pcb 5240-431 IECPlug
25960-117
Front Panel
W1 W2
W3
W4
Isolation Tx
Assy 6231-766
Battery12v4Ah
r
Assy 6180-454
25985-030
5kVHVAssy 6430-865
Meas Board
Pcb 5240-428
W5 W6 W7 W8
W9
W1 13497-095
W2 13497-100
W3 6140-388
W4 13497-100
W5 6140-388
W6 6140-388
W7 6140-388
W8 6180-454
W9 13497-100
W10 6140-387
W11 6140-387
W12 6140-387
W10 W11 W12
HV Board
Pcb 5240-430

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SERVICE MANUAL
Interconnect Diagram for MIT1020 models.
Note: The W numbers shown on this diagram are not the same as W numbers on assembly drawings.
Keyboard
Assy 6231-716
Pcb 5240-432
Display Board
Assy 6430-861
Pcb 5240-433 Serial Board
Assy 6231-758
Pcb 5140-987
Power Board
Assy 6331-804
Pcb 5240-431 IECPlug
25960-117
Front Panel
W1 W2
W3
W4
Isolation Tx
Assy 6231-766
Battery12v4Ah
r
Assy 6180-454
25985-030
10kVHVAssy 6430-864
Meas Board
Pcb 5240-428
W5 W6 W7 W8
W9
W1 13497-095
W2 13497-100
W3 6140-388
W4 13497-100
W5 6140-388
W6 6140-388
W7 6140-388
W8 6180-454
W9 13497-100
W10 6140-389
W11 6140-389
W12 6140-389
W10 W11 W12
HV Board
Pcb 5240-429

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SERVICE MANUAL
Section3. Battery charge calibration
A battery calibration charge sequence will need to be carried out after the following:
1. A new instrument has been fully assembled for the first time.
2. An instrument’s battery has been replaced.
3. An instrument’s display board has been replaced.
4. An instrument’s power supply board has been replaced.
The battery charge calibration procedure is as follows:
The charge sequence.
1. Switch on the unit and wait for the instrument to complete its initialisation. Note, if the battery becomes
disconnected for any reason during or after assembly briefly apply the mains to reset the battery circuit.
2. If mains power is not connected the instrument screen displays ‘bat’ and ‘start charge’. This instructs the user
to connect the instrument to mains power.
3. With mains power connected, the green ‘led’ next to the ‘on/off’ switch is lit, the screen displays ‘bat’ and the
segments of the battery monitor bar graph light sequentially indicating the battery is being charged.
4. After a charge period of 14 hours the instrument then enters a rest state for 2 hours. In this state the instruments
screen displays ‘bat’ and ‘resting bat’.
5. After the 2 hour rest period has elapsed the instrument screen displays ‘bat’ and ‘end charge’. The green ‘led’
flashes. This message remains on the screen until the mains power is disconnected.
6. When mains power is disconnected the screen displays ‘bat’ and ‘switch off’. The operator should now switch
the instrument off.
The discharge sequence.
1. Switch the instrument back on. The instrument screen displays ‘bat’ and ‘discharging’. The instrument remains
in this state for 15 minutes.
2. After the 15 minute period has elapsed, the instrument screen displays ‘switch off’. The operator should now
turn the instrument off. Battery calibration is now complete.
An instrument can be put into battery calibration mode at any time by connecting up a PC to the instrument
front panel RS232. Open the programme ‘S1-5XX, S1-10XX Test and Calibration Software’ and press the ‘Recal
Battery’ button. Switch the unit back on and follow the sequence described above.
The software is available for download from the Megger Limited website part number (6111-759). Support files for
this will have to be downloaded from the Microsoft™ website. A CD version (including the necessary support files) is
available on request.

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Blank Page

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Section 4. Electronic Circuit Description. Page
4.1 Power Board. 14
4.2 Display Board. 14
4.3 Key Board 14
4.4 Comms Boards. 15-16
4.5 Measurement Board. 17
4.6 ‘Hv’Board. 18
Note: Block diagrams provide an over view of a circuits function. For more detail consult circuit diagrams in
this service manual.

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Power Board, Display Board and Key Board Block Diagram.
Battery
Battery
Protect
Mains
Off Line Reg
Emc Filter
Isolation
Tx
BatteryVolts
Monitor
Charger
PSUBoard
HV Module
Iso Tx
SwitchReg
EEProm
DCPower and
Backlight supply
Power on and
watchdog
Lcd and
Driver
circuitry
Rs232/USB
Board
IRDAComs
Micro
Display Board
Keypad matrixBuzzer Leds
Key Board

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SERVICE MANUAL
The MIT510 serial board has the facility for USB communication, but the MIT510 instrument does not use USB communications.
RS 232 level
Translate
USB
EE
p
rom
USB/RS 232
Convertor 3.3 USB
3.3 USB
3.3
USB Rx
USB Tx
Buffer Level
Translate
Or gate
USB Connect RS232 Connect
Instrument
Connect
Switch
USB detect
Tx
Rx

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Isolated Comms
Or gate
RS 232 Buffer &
Iso Tx Drive
Iso Tx
RS232 Level Translate
& + rail generate
Regulate &
-- rail generate
USB/RS232
Convertor
+10v iso
--10v iso
3.3v iso3.3v USB
3.3v iso
RS232 Connect
USB detect
USB Connect
Instrument
Connect
Switch
USB Rx
USB Tx
Buffer Level
Translate
Opto
Tx
Rx

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Meas Board
Fuse
I meas
A5
A3
A6
A1
A8
A4
A2
A7
Low
Medium
High
Filter
Guard OK
Break Down Detect
Ac Detect
IRDA Coms
Power on,
Watchdog and
Flash circuit
To ‘Hv’ board
Discharge on/off
‘Hv’ on/off
Set ‘Hv’
Set current limit
G
__
0v
0v
Cap meas
Terminal volts meas
Micro
Attenuated ‘Hv’
From ‘Hv’ board
Attenuated ‘Hv’ from
Discharge path
ADC
0v
Discharge
Current Overrange
A9

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Pulse Width
Modulator
Oscillator
Current Limit
Feedback
Discharge
Attenuator
To ‘Meas’
board
Set ‘Hv’ from
‘Meas’ board
‘Hv’ on/off
Discharge on/off
From ‘Meas’ board
Attenuator
Capacitance meas
To ‘Meas’ board
HV Control Board
5240-429-A7 & below
5240-430-A9 & below

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Feedback
Pulse Width
Modulator
Oscillator
Current Limit
Discharge
Attenuator
To ‘Meas’
board
Set ‘Hv’ from
‘Meas’ board
‘Hv’ on/off
Discharge on/off
From ‘Meas’ board
Attenuator
Capacitance meas
To ‘Meas’ board
HV Control Board 5240-429-A8 & above
5240-430-A10 & above

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1st Used On:
SERVICE MANUAL
Section 5 Circuit Diagrams. Pages
5.1 Display Circuit Diagrams. 20 - 27
5.2 Keyboard and Engineering Board Circuit Diagrams. 28 - 31
5.3 Interface 10 & 20 Circuit Diagrams. 32 - 34
5.4 Isolated Interface Circuit Diagrams. 35 - 37
5.5 Power Supply Circuit Diagrams. 38 - 42
5.6 Measurement Circuit Diagrams. 43 - 50
5.7 5KV Generator Circuit Diagrams. 51 - 53
5.8 10KV Generator Circuit Diagrams. 54 - 56