JENCO VisionPlus 6377 User manual

Operation Manual
MODEL 6377
Microcomputer Based
pH/ORP/Cond/TDS/Salt/Temperature
Benchtop Meter
6377

1
CONTENTS
GENERAL INTRODUCTION 2
INITIAL INSPECTION 2
POWER INPUT 3
INSTALLING THE BATTERIES 3
CONNECTOR 4
DISPLAY & KEYS FUNCTIONS 4
A. Display 4
B. Keys 6
OPERATIONAL PROCEDURES 7
A. Buffer Set Selection 7
B. pH Calibration 7
C. pH Measurements 11
D. Temperature Measurements 12
E. mV Offset 12
F. mV (RmV) Measurements 13
G. Conductivity Calibration 13
H. Conductivity, Salinity, TDS Measurements 15
I. pH Buffers 16
J. Preparing Conductivity Standard Solutions 16
ERROR DISPLAYS AND TROUBLESHOOTING IN
pH/ORP MODE 18
ERROR DISPLAYS AND TROUBLESHOOTING IN
CONDUCTIVITY/SALINITY/TDS MODE 19
SPECIFICATIONS 20
WARRANTY 21

2
GENERAL INTRODUCTION
Thank you for selecting the 6377 meter. The 6377 is a precision tool
that measures pH, mV （RmV）, Conductivity, Salinity, TDS and
temperature. A built-in microprocessor stores, calculates and
compensates for all parameters related to pH and Conductivity
determinations including pH and Conductivity electrode temperature
characteristics, electrode slope deviations, offset and buffer
solutions.
This meter has a waterproof IP54 case. The mechanical keys are
highly reliable with tactile and audio feedback. It is powered by six
AAA-size alkaline batteries or with a UL / CE approved AC adapter
(OUTPUT:DC9V). The meter also displays a “BAT” message when
the batteries are in need of replacement. Re-calibration is not
required when power is restored.
The front of the meter has a large LCD that displays pH , mV , Rmv ,
Conductivity , TDS , Salinity and temperature simultaneously along
with user prompts and mode indicators. The unit prompts the user
through calibration and measurement procedures.
An AUTOLOCK feature for both pH and mV measurements enables
the unit to automatically sense the end point and “LOCK” the display
to indicate the end point value of a measurement. AUTOLOCK and
user prompts help eliminate most errors in determining pH and mV
values, resulting in precise, repeatable and error-free
measurements. The 6377 can also be used in non-AUTOLOCK
mode.
The model 6377 is available with pH, ORP, Conductivity and ATC
(Automatic Temperature Compensation) probes. Other features
include up to 5 points calibration for pH and, 1 point calibration for
both Conductivity and ORP, electrode offset recognition, electrode
slope recognition, electrode efficiency display, built-in buffer
coefficients, automatic or manual temperature compensation and
50/60 Hz AC noise rejection. This meter is user-friendly for
laboratory application.
INITIAL INSPECTION
Carefully unpack the unit and accessories. Inspect for damages
made in shipment. If any damage is found, notify your JENCO
representative immediately. All packing materials should be saved
until satisfactory operation is confirmed.

3
POWER INPUT
The model 6377 can be powered by an UL / CE approved 100 ~ 240
VAC adaptor as well as 6 “AAA” alkaline batteries. Check the label
on the AC adaptor supplied with the instrument to make sure that
the AC line voltage is correct. If the wrong AC adaptor is supplied,
notify your JENCO representative immediately.
INSTALLING THE BATTERIES
To insert the batteries into the meter, follow the procedure outlined
below.
1. Use a Philip screw driver and unlock the battery cover by
turning the screw driver in the counter clockwise direction.
After unlocking the screw, take off the battery cover (Fig.1)
2. Replace the old batteries with new ones and install them on
the correct polarity position.
3. Put the battery cover back on the instrument. Use a Philip
screw driver and turn the screw in the clockwise direction to
lock the battery cover.
Figure 1: Battery compartment

4
CONNECTOR
1 2 3
Figure 2: Connector
1. pH/ORP connector (BNC connector)
2. Conductivity/ATC connector (8 PIN connector)
3. AC adaptor input connector
DISPLAY & KEYS FUNCTIONS
A. 1. pH/ORP Display
1
2
3
4
5
6
7
9
10
12
11
81.68 4.01 7.00 10.01
4.00 6.86 9.18 12.46
Figure 3 : Active LCD screen
1. WAIT-
This will be displayed when the
unit is still waiting for a stable
reading or end point sensing.
7. AUTO-
AUTOLOCK mode indicator.
2. BAT-
Low battery indicator.
8. Buffer selection-
This indicator will flash if the
unit is not yet calibrated. This
indicator will remain lit-up if
the unit has been calibrated.

5
3. pH-
Unit and mode indicators.
9. LOCK-
This will indicate that the
reading is frozen during
AUTOLOCK mode.
4. mV (RmV)-
Unit and mode indicators.
10. EFF-
This will be displayed if the
user is viewing the efficiency
of the electrode.
5. ATC/MAN-
ATC indicator will be displayed
if a temperature probe is
connected otherwise the MAN
indicator will be displayed.
11. MAIN DISPLAY-
For pH, mV and probe
efficiency values
6. CAL-
This will be displayed when the
unit enters into the calibration
mode.
12. SECONDARY DISPLAY-
For temperature in ℃.
2. EC Display
1
2
3
4
5
6
7
8
9
10
11
12
Figure 4: Active LCD screen
1. mS/cm-
Millisiemens , indicates
Conductivity measurement.
7. mg/L-
Milligrams/Liter indicates TDS
measurement.
2. BAT-
Low battery indicator.
8. CELL K= -
Indicates conductivity cell
constant value.
3. uS/cm-
Microsiemens, indicates
Conductivity measurement.
9. %/ ℃-
Indicates Temperature
Coefficient

6
4. CAL-
This will be displayed when the
unit enters into the calibration
mode.
10. MAIN DISPLAY-
For Conductivity, Salinity and
TDS values.
5. AUTO-
Auto ranging indicator
11. SECONDARY DISPLAY-
For temperature in ℃.
6. ATC/MAN-
ATC indicator will be displayed
if a temperature probe is
connected otherwise the MAN
indicator will be displayed.
12. ppt-
Parts per thousand, indicates
Salinity measurement.
B. Keys
On/Off-
Press and hold this key for 2 seconds to power on
and shut off the meter.
Mea.
Eff.
Stand
Slope
Mode
Clear
Mode-
Selects display mode. Pressing this key changes the
display sequentially to display pH-AUTOLOCK, mV
(RmV)-AUTOLOCK, pH , mV (RmV) , Conductivity ,
Salinity and TDS . The calibration values will not be
affected by changing the display modes. In
“calibration”, press “Mode” key to exit calibration
mode.
Mea.
Eff.
Stand
Slope
Mode
Clear
Clear-
It is used to clear the unit when error signal appears. It
clears all calibration values stored in the internal
memory.
Under normal use the key will not be activated unless
pressed and held for 5 seconds to prevent accidental
erasing stored memory.
In pH, mV (Rmv) or conductivity (salinity, TDS) mode,
when the “Clear” key is pressed for 5 seconds, all
segments of the LCD will be lit on. After 2 seconds the
unit will enter the pH-AUTOLOCK mode,
mV-AUTOLOCK mode or conductivity mode, In the
pH mode, the “AUTO” and “CAL” icons will be
displayed and one of the buffer values in the
pre-selected buffer set will begin to flash. This means
that the unit is un-calibrated and requires new pH
calibration before use. In the ORP mode, the “AUTO”
and “mV” icons will be displayed. This means that the
unit is un-calibrated and requires new ORP
calibration before use. In the conductivity mode, the
“AUTO” icon will be displayed. This means that the
unit is requires new conductivity calibration before
use.
Mea.
Eff.
Stand
Slope
Mode
Clear

7
Mea.
Eff.
Stand
Slope
Mode
Clear
Mea.
Eff.
Stand
Slope
Mode
Clear
Up/Down-
In the pH/ORP/conductivity/salinity/TDS measure
mode, these two keys are used to manually enter the
temperature values. They have no effect on the unit
when operating in ATC mode.
In the ORP and conductivity calibration mode, these
two keys are used to adjust values in ORP or
conductivity.
Stand/Cal & Slope/Enter-
These two keys are used for pH, ORP and
conductivity calibration. For their specific functions,
please see the "calibration" section in each
parameter.
Mea.
Eff.
Stand
Slope
Mode
Clear
Mea. / Eff.-
1. The key is used to bring the unit out of the AUTO
condition when operating in the pH-AUTOLOCK or mV
(RmV)-AUTOLOCK mode.
2. In the pH mode, press and hold this key for 5
seconds, the LCD will display the efficiency of the
electrode and Offset value.
3. In the ORP mode, press and hold this key for 5
seconds, the LCD will display the electrode Offset value.
4. In the Conductivity, Salinity or TDS mode, press
and hold this key for 5 seconds, the LCD will display the
electrode cell K value.
OPERATIONAL PROCEDURES
A. pH Buffer Set Selection
The 6377 meter has two buffer sets: 1.68, 7.00, 4.01, 10.01, 12.46
pH and 1.68, 6.86, 4.00, 9.18, 12.46 pH.
To change the buffer set, turn off the unit, then press and hold the
“Stand/Cal” key while turning on the unit again.
[Note: There is no need to repeat this procedure every time the unit
is power up unless one decides to change the buffer settings.]
B. pH Calibration
The 6377 uses up to 5 points calibration.
[Note: If the device requires to calibrate more than one calibration
point, the first calibration point must be 6.86/7.00 pH.]
a. Calibration with an ATC/Temp probe in the pH-AUTOLOCK
mode.
1. Turn the unit on. In pH mode, press “Clear” key for 5
STAND
CAL
SLOPE
ENTER

8
seconds, all LCD elements will lit up. The meter clears all
calibration values stored in internal memory.
2. Connect the pH electrode to the BNC connector and the
ATC/Temp probe to the ATC/Temp connector of the unit:
“ATC” icon will lit up. “pH” icon and “AUTO” icon will lit up.
The "CAL" icon begins to flash.
3. Rinse the pH and ATC/Temp probes in distilled water and
immerse them in the first buffer solution. Allow temperature
reading to stabilize, then press and hold “Stand/Cal” key for 2
seconds to calibrate. The “WAIT” icon will flash until the unit
detects a stable reading. Once the unit calibrates the first
point, the selected buffer will lit up while two other selectable
buffers start to flash. The unit is ready to be sloped at the
second buffer.
[Note: If the first buffer solution is 7.00 or 6.86 pH, at this
moment, press the “Mode” key. The unit will exit the
calibration mode. Single point calibration is complete.
If the first buffer solution is 1.68,4.00, 4.01, 9.18 , 10.01 or
12.46 pH, at this moment, the unit will automatically exit the
calibration mode. Single point calibration is complete.]
4. Rinse the pH and ATC/Temp probe in distilled water and
immerse them in the second buffer solution (either 4.00 / 4.01
pH or 9.18 / 10.01 pH corresponding to the flashing number
on display). Allow temperature reading to stabilize, then press
“Slope/Enter” key to calibrate. The “WAIT” icon will flash
until the unit detects a stable reading. Once the unit calibrates
the second point, the selected two buffers lit up and the
remaining buffers start to flash. The unit is ready to be sloped
at the third buffer.
[Note: At this moment, press the “Mode” key, the unit will
exit the calibration mode. Dual point calibration is complete.]
5. The third point, the fourth point and the fifth point are the
same as the second point calibration. When the unit
completed the fifth point calibration, press the “Mode” key
and exit the calibration.
6. The unit calculates and compensates for the pH electrode
slope deviation corresponding to the values of the calibrated
buffers. After calibration, press and hold “Mea./ Eff.” key for
about 5 seconds to display the new electrode efficiency and
offset.
b. Calibration with manual temperature compensation in the
pH-AUTOLOCK mode.

9
1. Turn the unit on. In pH mode , press “Clear” key for 5
seconds, all LCD elements will lit up. The meter clears all
calibration values stored in internal memory.
2. Connect the pH electrode to the BNC connector of the unit,
“MAN” icon will lit up. “pH” icon and “AUTO” icon will lit up. The
"CAL" icon will begin to flash.
3. Rinse the pH probes in distilled water and immerse it in the
first buffer solution. Adjust the temperature reading to that of the
first buffer using the “Up” or “Down” keys (0.0 ~ 60.0 ℃).
Then press and hold “Stand/Cal” key for 2 seconds to
calibrate. The “WAIT” icon will flash until the unit detects a
stable reading.
4. Once the unit calibrates the first point, the selected buffer
remains lit up while two other selectable buffers start to flash.
The unit is ready to be sloped at the second buffer.
[Note: If the first buffer solution is 7.00 or 6.86 pH, at this
moment, press the “Mode” key, the unit will exit the
calibration mode. Single point calibration is complete.
If the first buffer solution is 1.68, 4.00, 4.01, 9.18, 10.01 or
12.46 pH, at this moment, the unit will automatically exit the
calibration mode. Single point calibration is complete.]
5. Repeat steps 4 of “Calibration with an ATC/Temp probe in
the pH-AUTOLOCK mode” for 2 to 5 points calibration.
c. Calibration with an ATC/Temp probe in the pH NON-
AUTOLOCK mode.
1. Turn the unit on. In pH mode, press “Clear” key for 5 seconds,
all LCD elements will lit up. The meter clears all calibration
values stored in internal memory.
2. Connect the pH electrode to the BNC connector and the
ATC/Temp probe to the ATC/Temp connector of the unit:
“ATC” icon will lit up. Press “Mode” key to select “pH” mode.
“pH” icon is on. The "CAL" icon will begin to flash.
3. Rinse the pH and ATC/Temp probes in distilled water and
immerse them in the first buffer solution. Allow temperature
reading to stabilize, then press and hold “Stand/Cal” key for 2
seconds to calibrate, the unit immediately calibrates the first
point, the selected buffer remains lit up while two other
selectable buffers start to flash. The unit is ready to be sloped
at the second buffer.
[Note: If the first buffer solution is 7.00 or 6.86 pH, at this

10
moment, press the “Mode” key, the unit will exit the calibration
mode. Single point calibration is complete.
If the first buffer solution is 1.68, 4.00, 4.01, 9.18, 10.01 or
12.46 pH, at this moment, the unit will automatically exit the
calibration mode. Single point calibration is complete.]
4. Rinse the pH and ATC/Temp probe in distilled water and
immerse them in the second buffer solution (either 4.00/4.01
pH or 9.18/10.01 pH corresponding to the flashing number on
display). Allow temperature reading to stabilize, then press
“Slope/Enter” key to calibrate. The unit immediately
calibrates the second point, the selected two buffers lit up and
the remaining buffers start flash. The unit is ready to be sloped
at the third buffer.
[Note: At this moment, press the “Mode” key, the unit will
exit the calibration mode. Dual point calibration is complete.]
5. The third point, the fourth point and the fifth point are the
same as the second point calibration. When the unit
completed the fifth point calibration, press the “Mode” key
and exit the calibration.
6. The unit calculates and compensates for the pH electrode
slope deviation corresponding to the values of the calibrated
buffers. After calibration, press and hold “Mea./Eff.” key for
about 5 seconds to display the new electrode efficiency and
offset.
d. Calibration with manual temperature compensation in the
pH NON-AUTOLOCK mode.
1. Turn the unit on. In pH mode, press “Clear” key for 5 seconds,
all LCD elements will lit up. The meter clears all calibration
values stored in internal memory.
2. Connect the pH electrode to the BNC connector of the unit,
“MAN” icon will lit up. Press “Mode” key to select “pH” mode.
“pH” icon is on. The "CAL" icon will begin to flash.
3. Rinse the pH probes in distilled water and immerse it in the
first buffer solution. Adjust the temperature reading to that of
the first buffer using the “Up” or “Down” keys (0.0 ~ 60.0 ℃)
before pressing “Stand/Cal” key. Then press and hold
“Stand/Cal” key for 2 seconds to calibrate. The unit
immediately calibrates the first point, the selected buffer
remains lit up while the remaining buffers start to flash. The
unit is ready to be sloped at the second buffer.
[Note: If the first buffer solution is 7.00 or 6.86 pH, at this
moment, press the “Mode” key, the unit will exit the calibration

11
mode. Single point calibration is complete.
If the first buffer solution is 1.68, 4.00, 4.01, 9.18, 10.01 or
12.46 pH, at this moment, the unit will automatically exit the
calibration mode. Single point calibration is complete.]
4. Repeat steps 4 of “Calibration with an ATC/Temp probe in
the pH NON- AUTOLOCK mode” for 2 to 5 points calibration.
C. pH Measurements
To take pH measurements, 6377 must be calibrated before first
use.
a. Measurement with an ATC/Temp probe in the pH-
AUTOLOCK mode.
1. Connect the pH electrode to the BNC connector and the
ATC/Temp probe to the ATC/Temp connector of the unit. The
“ATC” icon will lit up.
2. Press “Mode” key until “pH” icon and “AUTO” icon lit up.
3. Rinse the pH electrode and ATC/temp probe with distilled
water and immerse in the sample to be measured. Remove
any air bubbles trapped around the probe by shaking or
stirring the probe.
4. Press the “Mea./Eff.” key. The “WAIT” icon will start flashing.
The unit is waiting for a stable reading. The display will track
the pH value as sensed by the pH electrode and the
ATC/Temp probe.
5. When the “WAIT” icon disappears, the reading is then “LOCK”
and will not respond to further changes from the sample. The
pH value shown is the pH value of the sample at the displayed
sample temperature.
[Note: For samples that are inherently unstable, the unit will
not AUTOLOCK. In this case, use the pH NON- AUTOLOCK
mode for measurements.]
b. Measurement with manual temperature compensation in
the pH-AUTOLOCK mode.
1. Connect the pH electrode to the BNC connector of the unit.
The “MAN” icon will lit up. Set unit to display the sample
temperature by pressing the “Up” and “Down” keys (0.0 ~
100.0 ℃).
2. Repeat steps 2 ~ 5 of “Measurement with an ATC/Temp
probe in the pH- AUTOLOCK mode”.

12
c. Measurement with an ATC/Temp probe in the pH NON-
AUTOLOCK mode.
1. Connect the pH electrode to the BNC connector and the
ATC/Temp probe to the ATC/Temp connector of the unit. The
“ATC” icon will lit up.
2. Press “Mode” key until “pH” icon lit up.
3. Rinse the pH electrode and ATC/temp probe with distilled
water and immerse in the sample to be measured.
4. Allow sufficient time for the display to stabilize. The instrument
will display the pH value of the sample at the displayed sample
temperature.
d. Measurement with manual temperature compensation in
the pH NON-AUTOLOCK mode.
1. Connect the pH electrode to the BNC connector of the unit.
The “MAN” icon will lit up. Set unit to display the sample
temperature by pressing the “Up” and “Down” keys (0.0 ~
100.0 ℃).
2. Repeat steps 2 ~ 4 of “Measurement with an ATC/Temp
probe in the pH NON- AUTOLOCK mode”.
D. Temperature Measure
The 6377 can measure temperature independently with the
ATC / temp probe without using the pH electrode. Place the
ATC / temp probe in the sample. The unit will display the
measured temperature.
E. mV Offset
1. Turn the unit on. In mV mode, press “Clear” key for 5
seconds, all LCD elements will lit up. The meter clears all
calibration values stored in internal memory.
2. Connect the ORP electrode to the BNC connector of the unit,
“MAN”, “mV” and “AUTO” icons will lit up.
3. Rinse the ORP probes in distilled water and immerse it in the
standard solution. Then press and hold “Stand/Cal” key for 2
seconds to calibrate. The “CAL” & “RmV” icons will lit up.
According to the mV (RmV) value displayed, press the “Up”
and “Down” keys to adjust the display value to the same
value as the standard solution. Press the “Slope/Enter” key
to save and complete the calibration.

13
F. mV (RmV) Measurements
a. Measurement in the mV (RmV)-AUTOLOCK mode.
1. Connect the optional combination ORP electrode to the BNC
connector of the unit.
2. Press “Mode” key until “mV” or “RmV” icon and “AUTO” icon
lit up.
3. Rinse electrode with distilled water and immerse it in sample to
be measured.
4. Press the “Mea. / Eff.” key. The “WAIT” icon will start flashing.
The unit is waiting for a stable reading. The display will track
the mV (Rmv) value as sensed by the ORP electrode
5. When the “WAIT” icon disappears, the reading is then “LOCK”
and will not respond to further changes from the sample. The
mV (RmV) value is the sample reading.
[Note: For samples that are inherently unstable, the unit will
not AUTOLOCK. In this case, use the mV (RmV) NON-
AUTOLOCK mode for measurements.]
b. Measurement in the mV (RmV) NON-AUTOLOCK mode.
1. Connect the optional combination ORP electrode to the BNC
connector of the unit.
2. Press “Mode” key until “mV” or “RmV” icon lit up.
3. Rinse electrode with distilled water and immerse it in sample to
be measured.
4. Allow sufficient time for the display to stabilize. The instrument
will display the mV (RmV) value of the sample.
G. Conductivity Calibration
Calibration setup contains six sections: TDS Constant,
Temperature Coefficient, Temperature Reference, Probe
Basic Cell Constant, Standard Solutions Calibration and K
Value Input. To access these sections:
1. Connect the conductivity probe to the unit and turn the unit
on.
2. In conductivity mode, allow temperature reading to stabilize,
press “Stand/Cal” key to enter the calibration mode. “CAL” &
“ATC” (MAN) icons appears on the LCD.

14
[Note: Press “Slope/Enter” key to accept any values
changes in each section and automatically advance to the
next section. If there are no changes, the unit accepts the
current value and proceeds to the next section.]
TDS Constant
TDS is determined by multiplying conductivity (mS/cm) by a
TDS factor. The default factor value is 0.65. To change the
TDS factor, use the “Up” and “Down” keys to adjust the
value between 0.30 ~ 1.00. Press “Slope/Enter” key to save
the new value and go to the next calibration parameter.
Temperature Coefficient
The unit uses the temperature coefficient to calculate
temperature compensated conductivity. The default value is
1.91%. To change the Temperature Coefficient, use the “Up”
and “Down” keys to adjust the value between 0.00 ~ 4.00%.
Press “Slope/Enter” key to save the new value and go to the
next calibration parameter.
Temperature Reference
The unit uses the temperature reference value to calculate
temperature compensated conductivity. The default value is
25 ℃. To change the temperature reference, press the “Up”
and “Down” keys to adjust the value between 15 ~ 25 ℃.
Press “Slope/Enter” key to save the new value and go to the
next calibration parameter.
Probe Basic Cell Constant
The main display shows the Cell Constant of the conductivity
probe (calibrated previously or default, the deviation range is
70% ~ 130%). The secondary display shows the current
selected cell constant which is either 0.10 or 0.475. Press the
“Up” and “Down” keys to select the one you want to use.
Press “Slope/Enter” key to save the new value and go to the
next calibration parameter.
Standard Solutions Calibration
Immerse the probe in a standard of known conductivity solution
(See section Preparing Standard Solutions), preferably a
standard in the middle range of the solutions to be measured.
Immerse the probe (at least 2” to 3” or 5 ~ 7cm from the tip)
without touching the sides of the calibration container. Shake
the probe lightly to remove any air bubbles trapped in the
conductivity cell. The unit will display the conductivity value.

15
Wait for the values of temperature and conductivity to stabilize
for a few seconds. Press the “Up”and “Down”keys to
adjust the reading of the display until it matches the value of the
known standard conductivity solution at 25 ℃. Press the
“Slope/Enter” key to save and exit the calibration.
[Note: If you want input K value directly, press the
“Slope/Enter” key to go to the K Value Input.]
K Value Input
The unit will display the cell constant value of the conductivity
probe with the CELL K= staying on. Adjust the probe constant
to a known value by pressing the “Up” and “Down” keys. You
can now input the K value (from 70% ~ 130% of the probe
basic cell constant). Press the “Slope/Enter” key to exit
calibration and return to normal operation.
H . Conductivity, Salinity, TDS Measurements
1. Turn the unit on. Place the probe in the solution to be
measured. Immerse the probe (at least 2” to 3” or 5 ~ 7cm
from the tip). Shake the probe lightly to remove any trapped
air bubbles in the conductivity cell.
2. Press “Mode” key to enter the desired measurement mode
(Conductivity, Salinity or TDS). The message“rAn9” may
appear briefly on the display indicating auto-ranging; this is
normal. Allow temperature to stabilize before taking
measurements.

16
I. pH Buffers
The temperature coefficient of pH calibration buffers 1.68, 4.00,
4.01, 6.86, 7.00, 9.18 , 10.01 and 12.46 pH are stored inside the
instrument. The buffers used to calibrate the instrument must
exhibit the same temperature characteristics as the stored
values.
Temperature coefficient of the pH buffers
°C
1.68
4.00
6.86
9.18
4.01
7.00
10.01
12.46
0
1.67
4.01
6.98
9.46
4.01
7.11
10.32
13.42
5
1.67
4.00
6.95
9.39
4.01
7.08
10.25
13.21
10
1.67
4.00
6.92
9.33
4.00
7.06
10.18
13.01
15
1.67
4.00
6.90
9.28
4.00
7.03
10.12
12.80
20
1.68
4.00
6.88
9.23
4.00
7.01
10.06
12.64
25
1.68
4.00
6.86
9.18
4.01
7.00
10.01
12.46
30
1.68
4.01
6.85
9.14
4.01
6.98
9.97
12.30
35
1.69
4.02
6.84
9.10
4.02
6.98
9.93
12.13
40
1.69
4.03
6.84
9.07
4.03
6.97
9.89
11.99
45
1.70
4.04
6.83
9.04
4.04
6.97
9.86
11.84
50
1.71
4.06
6.83
9.02
4.06
6.97
9.83
11.71
55
1.72
4.07
6.83
8.99
4.08
6.97
9.80
11.57
60
1.72
4.09
6.84
8.97
4.10
6.98
9.78
11.45
[Note: The actual reading of the instrument can differ from the
values shown by ±0.01 pH ]
J. Preparing Conductivity Standard Solutions
Suitable conductivity standards are available commercially or
the user can prepare them using research grade reagents.
Here are some standard solutions the user can prepare to
calibrate the probe of the model 6377.
1. Standard solution of 1413 uS/cm at 25 ℃: Accurately weight
out 0.746 grams of research grade dried Potassium Chloride
(KCL). Dissolve in 1000 ml of distilled water.
2. Standard solution of 12.90 mS/cm at 25 ℃: Accurately weight
out 7.4365 grams of research grade dried Potassium Chloride
(KCL). Dissolve in 1000 ml of distilled water.

17
3. Standard solution of 111.9 mS/cm at 25 ℃: Accurately weight
out 74.264 grams of research grade dried Potassium Chloride
(KCL). Dissolve in 1000 ml of distilled water.
[Note: You can store the unused portion of the standard
solution in a plastic container for six months but the air space
between the cap and the solution must be kept to an absolute
minimum. Storing the excess solution below 4 ℃can increase
the storage life. If you have any doubt of the accuracy of the
stored solution, a fresh batch should be prepared.]

18
ERROR DISPLAYS AND TROUBLESHOOTING IN
pH/ORP MODE
Main
Display
Possible cause(s)
Corrective Action(s)
"Er1"
1. “Stand/Cal” was
pressed before the
electrode and ATC/Temp
probe settled to within
+/-1.00 pH of the buffer
value.
2. pH electrode offset is
greater / less than +/-1.00
pH.
3. pH electrode is faulty.
1. Press “Clear” key, allow
sufficient time for the
electrode and ATC / Temp
probe to stabilize, re-press
“Stand/Cal” key to start
the calibration procedure.
2. Replace the buffer and /or
the pH electrode. Press
“Clear” key to recalibrate
meter.
3. Replace electrode.
"Er2"
1. “Slope/Enter” was
pressed before the
electrode and ATC/Temp
probe settled to within
30% of the buffer value.
2. Buffer 1.68, 4.00, 4.01,
9.18, 10.01 and 12.46 pH
is not correct.
3. pH electrode slope is off
by more than 30% of
ideal slope.
1. Allow sufficient time for the
electrode and ATC/Temp
probe to stabilize, re-press
“Slope/Enter” key to
continue the calibration
procedure.
2. Check if the correct buffer
is used.
3. Replace the buffer and /or
the pH electrode. Press
“Clear” key to recalibrate
meter.
"Er3"
In pH calibration mode
Temperature is out of the
0.0 ~ 60.0 °C range.
Bring the pH buffer
temperature within range.
"over"
/ ”undr”
1. Measured pH is out of
the -2.00 ~ 16.00 pH
range.
2. Measured mV (RmV) is
out of the –1999.9 ~
1999.9 mV range.
3. Measured temperature is
out of the 0.0 ~ 100.0 °C
range.
1. Bring sample pH into the
correct measuring range.
2. Bring sample ORP into the
correct measuring range.
3. Bring sample temperature
into the correct measuring
range.

19
ERROR DISPLAYS AND TROUBLESHOOTING IN
CONDUCTIVITY / SALINITY / TDS MODE
[Note: If the meter still does not perform normally after the above
measures are taken, call JENCO representative.]
Main
Display
Secondary
Display
Possible cause(s)
Corrective
Action(s)
"over" during
measurements
0.0 ~
100.0 ℃
1. Sample
Conductivity
value > 200.0
mS/cm; Sample
TDS > 200 g/L.
Sample Salinity >
80.0 ppt
2. Conductivity cell
contaminated or
defective.
3. Incorrect K
constant value
input.
1. Sample cannot
be tested
.
2. Decontaminate
/ clean cell or
replace cell.
3. Input correct K
value.
"over" during
calibration
0.0 ~
100.0 ℃
1. Incorrect standard
solution.
2. Conductivity cell
contaminated or
defective.
3. Incorrect K
constant value
input.
1. Replace
standard
solution.
2. Decontaminate
/ clean cell or
replace cell.
3. Input correct K
value.
"over " during
measurements
over
1. Sample
temperature >
100 ℃.
2. Defective
conductivity cell.
1. Reduce
sample
temperature.
2. Replace cell.
undr
1. Sample
temperature
< 0.0 ℃
2. Defective
conductivity cell.
1. Increase
sample
temperature.
2. Replace cell.