YOKOGAWA 2769 User manual

2769
Portable Double Bridge
User's
Manual
IM 2769-10E
IM 2769-10E
6th Edition: Oct. 2017 (YMI)

IM 2769-10E
―i ―
Introduction
Thank you for purchasing the 2769 Portable Double Bridge.
This User’s manual contains useful information regarding the instrument’s functions and
operating procedures, as well as precautions that should be observed during use.
Before using this product, thoroughly read this manual to understand how to use it properly.
Contact information of Yokogawa offices worldwide is provided on the following sheet.
PIM 113-01Z2: Inquiries List of worldwide contacts
Notice regarding This Document and User’s Manual
• The information covered in this User’s manual is subject to change without prior notice.
• Every effort has been made to ensure accuracy in the preparation of this manual.
Should any errors or omissions come to your attention however,
please inform YOKOGAWA accordingly.
• YOKOGAWA is by no means liable for any damage resulting from
the user’s mishandling of the product.
• This manual is intended to describe the functions of this product.
YOKOGAWA does not guarantee that these functions are suited to
the particular purpose of the user.

IM 2769-10E
―ii ―
Cautionary Notes for Safe Use of the Product
When operating the instrument, be sure to observe the cautionary notes given below to
ensure correct and safe use of the instrument. If you use the instrument in any way other than as
instructed in this manual, the instrument’s protective measures may be impaired.
YOKOGAWA is by no means liable for any damage resulting from use of
the instrument in contradiction to these cautionary notes.
■ The following safety symbols are used on the instrument and in this manual.
Danger! Handle with Care.
This mark indicates that operator must refer to an explanation in
the instruction manual in order to avoid risk of injury or death of
personnel or damage to the instrument.
■ Since mishandling the instrument can result in an accident that may lead to
injury or death of the operator, such as an electric shock, be sure to observe
the following instructions.
WARNING
● Protective Measures
• If a crack appears in the instrument after it has been accidentally dropped or bumped,
the safety-purpose insulation may be damaged.
By all means do not use the instrument, but ask the manufacture for repair.
● Connection
• To avoid electric shock, be sure to apply protective grounding to the grounding terminal.
• Install a protection fuse as shown in the example of measurement.
● Measurement
• Always maintain the instrument within the limits for allowable current, voltage and power,
during operation.
If there is more than one limit for any of these parameters, the lowest limit takes precedence.
● External Power Supply
• Only operate the instrument on a supply voltage no greater than 60 VDC.
● Operating Environment
• Do not operate the instrument in a flammable or explosive gas atmosphere.
• Do not operate the instrument if there is any condensation on it.
● Do Not Remove the Case or Disassemble
• Do not open the case except when replacing batteries or fuse.
Only Yokogawa service personnel are authorized to remove the casing or disassemble or
modify the instrument.
Do not attempt to repair the instrument yourself, as doing so is extremely dangerous.

IM 2769-10E
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■ Since mishandling the instrument can result in an accident, such as an electric shock,
that may injure the operator or damage the instrument, be sure to observe
the following instructions.
CAUTION
● Batteries
• Do not use a mixture of different types of batteries or a mixture of old and new batteries.
If the instrument will not be used for a prolonged period, remove the batteries before storage.
The battery fluid will leak more readily during long-term storage, resulting in an instrument
malfunction.

IM 2769-10E
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CONTENTS
Introduction ....................................................i
Cautionary Notes for Safe Use of the Product .........................ii
1. GENERAL...................................................1
2. SPECIFICATIONS ............................................1
3. COMPONENT NAMES AND FUNCTIONS .........................3
4. OPERATING INSTRUCTIONS...................................7
4.1 Preparation..............................................7
4.2 Operation for Measurement.................................7
4.3 Accessories .............................................9
5. CAUTIONS.................................................10
5.1 Cautions for Operation....................................10
5.2 Cautions for Maintenance .................................10
5.3 Calibration .............................................10
5.3.1 General Check.....................................10
5.3.2 Check on Operation.................................10
5.3.3 Calibration of Standard Resistor .......................11
5.3.4 Calibration of Measuring Arm Dial ......................11
6. PRINCIPLE OF OPERATION...................................12
6.1 Basic Principles .........................................12
6.2 Error..................................................12
6.2.1 Error due to Current Lead ............................12
6.2.2 Error due to Potential Lead ...........................13
7. CIRCUIT DIAGRAMAND PARTS LIST ...........................15

IM 2769-10E
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1. GENERAL
The Portable Double Bridge 2769 is quite convenient with low resistance measurement from
1 mΩ to 110 Ω.
This double bridge contains an electronic galvanometer and bridge power supply to
facilitate the operation.
2. SPECIFICATIONS
Measuring Range: 0.100 mΩ to 110.0 Ω
Accuracy: ±{ 0.05 Ω × (multiplaying factor) + 0.01 mΩ }
at ambient temperature 5 to 35°C, and
the lead resistance between C2 terminals and Rx is less than 20 mΩ.
Measuring Dial: 1.00 to 11.00 Ω, 0.05 Ω minimum division
0.0001 *
0.001
0.01
0.1
1
10
0.1ΩmΩto 1.1 mΩ
1 mΩto 11 mΩ
0.01 Ωto 0.11 Ω
0.1 Ωto 1.1 Ω
1 Ωto 11 Ω
10 Ωto 110 Ω
0.01 Ω
0.1 Ω
1 Ω
10 Ω
100 Ω
1000 Ω
10 A
3 A
1 A
0.3 A
0.1 A
0.01 A
±0.1%
±0.1%
±0.1%
±0.1%
±0.1%
±0.1%
Multiply Measuring range Resistance Accuracy Max. current
Standard Resistor
* with an external STANDARD RESISTOR 2771
Table 2.1 Multiply v.s. Standard Resistor

IM 2769-10E
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Electronic Galvanometer
Voltage sensitivity: approx. 20 μV/div.
Input resistance: approx. 11 kΩ
Sensitivity dial:
G
0
(input resistance: approx. 11 kΩ)
G
1=
G
2=
G0 (input resistance: approx.11 kΩ)
G0 (input resistance: approx.11 kΩ
）
GA, OFF and B check
1
11
1
110
Power source: 9 V (dry cell Type 006P)
Battery life: approx. 300 h
Bridge Power Source
Voltage: 1.5 V
(dry cell UM-1 or SUM-1, two cell are parallel connected.)
Max. current supply: approx. 1 to 2 A
Battery life: more than 1200 measurement
(50% duty cycle, 15 sec maximum on-time)
Operating Temperature and Humidity Range:
5 to 35°C, Less than 85%
Dimensions: Approx. 182 × 226 × 118 mm (excluding handle and rubber feet.)
Approx. 196 × 226 × 130 mm (including handle and rubber feet.)
Weight: Approx. 2.6 kg (5.7lbs)
Accessories: Plug (A1025WX)
User’s Manual
Carrying case (B9350AW)
Optional accessories: Standard Resistor 277100
(0.01 Ω ±0.1%, with three leadwires)
Approx. 30 × 175 × 63 mm
Approx. 0.25 kg

IM 2769-10E
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3. COMPONENT NAMES AND FUNCTIONS
OFF
GA
OFF
BA ON GA
Ω
MULTIPLY
MAX CURRENT (A)
×10
0.01 0.1 0.3 1 3
×1 ×0.1 ×0.01 ×0.001
EXT BA
G2
CH G1
G0
C2S
C2 P2 C1P1P2S
P1S
A
A
(INT BA)
(EXT BA)
Rx
[4]
[3]
[7]
[6]
[2]
[1]
[9][8]
[5] Zero Adjustor
[10]
Rx
20 20
10 10
0
GALVANOMETER
B
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.5
7.0
8.0
7.5
8.5
6.0
2.0
1.5
1.0
11.0
10.5
10.0
9.5
9.0
Front Panel
Fig. 3.1 Front Panel
[1] Measuring Dial
This dial is used to adjust the measuring arm.
[2] Multiplying Factor Switching Plug
The multiplying factor is selected by this plug.
[3] Battery Switch
This switch turns on/off the power to the bridge.
[4] Galvanometer Button Switch
The galvanometer is connected to the bridge by depressing this switch.
This switch is locked by turning it clockwise or counterclockwise while keeping it depressed.

IM 2769-10E
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[5] Galvanometer Sensitivity Dial
The galvanometer sensitivity is selected by this dial;
G0gives the highest sensitivity, G1is medium, and G2is lower than G1.
With this switch, the galvanometer driving battery can be checked through observing the meter.
When the pointer is deflected to the blue zone, this shows that the battery is good.
Also, this switch turns on/off the galvanometer driving battery.
[6] INT. BA Terminals
When the self-contained battery is used to supply power to the bridge,
these terminals are short-circuited by the short-bar.
[7] EXT. BA Terminals
When an external power supply is used, these terminals are short-circuited by the short-bar.
[8] Rx Terminals
An unknown resistance is connected to these terminals.
The Rx terminals consist of current terminals C1, C2and potential terminals P1and P2.
[9] P2S Terminal
This is one of the potential terminals to which the Standard Resistor 2771 is connected.
[10] EXT. BA Terminals
An external battery is connected across these terminals.
The minus (-) side of the terminals is one of the current terminals to
which the External Standard Resistor is connected.

IM 2769-10E
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Battery Replacement
The self-contained batteries are located in the bottom of the instrument case.
To open the battery cover, push the clamping plate thoroughly in the arrow direction,
and raise the foot of the cover.
While, to close the cover, push the clamping plate in the arrow direction, fit the edge A-A’ with
the groove of the instrument body, and depress the cover.
The stopper will lock the cover in its place.
Since two batteries are used in parallel connection, replace them with two new ones at a time.
Note that use of old battery in combination with new one will result in short battery life.
Fig. 3.2 Removal of the Battery Cover
A A’
Fig. 3.3 Location of Batteries