Kett HG-770 User manual

Lumber Moisture Tester HG-770
Operating Manual

Contents
1. Part Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
2. Operating the HG-770 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
3. Alarm Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
4. The Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
5. Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1
1. Part Names
1. Main Unit Upper Limit Value Setting Display
Moisture Content Value Display
Lower Limit Value Setting Display LED Displays
Upper Limit Value Setting Keys
Wood Type Select Switches (BROAD/NEEDLE)
Power Switch
Voltage Selector
Fuse Holder
Ground Terminals
AC Output
Connector
Buzzer Output
Connector
Sensor Connector
RS-232C Output Connector
Power Supply Connector
(Alarm Output)
Sheet Panel
Temperature Setting Dial
Lower Limit Value Setting Keys

2
2. Accessories
8Option
(Needle Roller Sensor)
34-Pin Connector
7Operating Manual
1Sensor Cable 2Power Supply Cord 4Buzzer
Lumber Moisture Tester HG-770
5Extra Needles 6Hexagonal Wrench

3
1. First, check to make sure that the voltage selector voltage indicator is
matched to the AC power supply voltage.
Reset the voltage selector as described below if it is not set to the
correct voltage.
(1) Use a regular screwdriver to rotate the voltage selector so that the
groove in the center points to the correct AC power supply voltage.
(2) Check to make sure that there is a fuse installed in the fuse holder.
2. Connect the Power Supply Cord and Sensor Cable to the main unit. Connect a ground wire to the Ground Terminal and
be sure to ground properly. Depending on environmental conditions, it may not be possible to obtain accurate measure-
ment results if the unit is not grounded properly.
Note:
Make the RS-232C, buzzer and AC Output Connector connections as necessary. Please refer to section 4., “The Serial
Interface” regarding the RS-232C output format.
Note:
When the Upper Limit Setting described on page 5 is performed, an AC current is output from the AC Output Connector
in accordance with the settings made. Be very careful to avoid electric shock.
Voltage Indicator Window
Voltage Selector
2. Operating the HG-770

4
3. Turn the Power Switch on.
At first “ 8” will appear in all of the LED displays and then the Lower Limit Setting Value, Upper Limit Setting Value
and Moisture Content Value will be displayed. The values displayed initially are the previously set values. The
settings are retained in the unit’s memory even if the power is turned off.
When the measured moisture content of the wood is outside the unit’s measurement range (7 ~ 35%), “ LO ” will
appear in the display if the moisture content is below the measurement range and “ HI ” will appear if the moisture
content is above the measurement range.
“ LO ” will also appear if the sensor needles are not inserted into wood.
4. Wood Type Setting
If the wood of broad-leafed trees is to be measured, press the BROAD Wood Type Select Switch. If the wood of
needle-leafed trees is to be measured, press the NEEDLE switch.
When BROAD is selected the key top lights green and when NEEDLE is selected the key top lights red.
Note:
Lauan wood is an exception and the NEEDLE Wood Type Select Switch should be pressed when measuring it.

5
5. Temperature Setting
Set the Temperature Setting Dial to the temperature of the material being measured.
The dial is graduated from 0˚ ~ 40˚C in 5˚C increments. The temperature cannot be set to an intermediate value
between increments.
6. Upper Limit • Lower Limit Value Setting
Upper and lower limit values can be set in order to use the HG-770 for moisture content management. When the
measured moisture content value falls outside the set limits, an alarm buzzer sounds, the set value blinks in the
display and an alarm signal is output simultaneously. The limit values can be set between 7 and 35% in 1% incre-
ments. The upper and lower limit values can each be changed by pressing the corresponding select switches. The
key is used to increase the setting value in both upper and lower limit setting and the key is used to decrease
the setting value in both upper and lower limit setting. However, it is not possible to set the upper limit to a value
lower than the lower limit. If this is attempted, “ ” will blink in the display. If this indicator appears in the display, be
sure to use the or keys to set the limit values so that numeric values appear in the display or otherwise measure-
ment will not be possible.

6
7. Releasing the Upper and Lower Limit Settings
To release the upper limit setting, hold down the Upper Limit Value Setting key until the setting value exceeds 35.
The display will indicate “ –– ” and the upper limit setting is released. To
release the lower limit setting, hold down the Lower Limit Value Setting key until the setting value decreases to 7
or less. The display will indicate “ –– ” and the lower limit setting is released.
8. Moisture Content Value Correction
When hard woods or woods with large moisture content gradients are measured, the measured moisture content
value tends to be lower than the actual moisture content. In these types of cases, it is necessary to make an upward
correction in the moisture content value. The possible correction range is 0 ~ +50% in 5% increments. When the
correction is set to zero, the displayed moisture content y1= (1 + 0.01 * x) y0where x% is the correction factor and y0
is the measured moisture content value.

7
Setting Procedure
(1) Set the Temperature Setting Dial to the position shown in the diagram on the
right.
(2) With the dial set to this position, press the BROAD switch. A correction value
of 0 ~ 50 (in increments of 5) will appear in the display. Each successive press
of the BROAD key increments the correction value by +5. (After 50 the correc-
tion value returns to 0).
(3) When the desired correction value is set, press the NEEDLE switch. The cor-
rection value setting procedure is complete and the display returns to the
moisture content value display. Once the correction value has been set it
remains in the unit’s memory even if the power is turned off.

8
The HG-770 features the following buzzer and AC alarm outputs.
(1) Buzzer Output
The buzzer sounds when the measured moisture content value is equal to or greater than the upper limit value setting.
(2) AC Output
AC current is output from terminals 1and 2when the measured moisture content value is equal to or greater than the
upper limit value setting.
AC current is output from terminals 3and 4when the measured moisture content value is equal to or less than the
lower limit value setting.
Notes:
1. The maximum allowable AC output is 250V, 1A. Be sure that
the load never exceeds this.
2. Terminals 1and 2are connected to one of the AC power sup-
ply poles at all times. These terminals are not necessarily on the
grounded side. Terminals 1~ 4are connected inside the main
unit as shown in the diagram on the right.
3. The moisture content signal A/D conversion capability is approximately 10 times per second.
The sampling data is compared with the set lower and upper limit values each time. However, in order to make the
moisture content value display easier to read, the maximum value encountered in 5 consecutive samplings of data
is displayed. For this reason, in some cases an alarm may be output if the measured moisture content value momen-
tarily drops below the lower limit value, even though the moisture content value displayed is higher than the lower
limit setting.
3. Alarm Output

The HG-770 features an RS-232C output.
The unit’s output format is as indicated below.
• Output Format
9
STX ,,,,
Measured
Moisture
Content
Value
Set Tem-
perature
ETX CR LF
• The following information is output in sequential ASCII code as data:
START : 1 bit
DATA : 7 bits
PARITY : 1 bit (even)
STOP : 1 bit
BAUD RATE : 9600 baud
START DATA PARITY STOP
1 1 1
7
4. Serial Interface
Upper
Limit
Setting
Value
Lower
Limit
Setting
Value
Set Wood
Type
(N/B)

10
1. Measurement Method : Direct current resistance (needle roller sensor)
2. Measurement Range : 7% ~ 35% (1% resolution)
3. Precision : ±1% (7% ~ 14%)
±2% (15 ~ 35%)
4. Alarm Setting : Upper and lower limit setting between 7% and 35%
5. Alarm Output : 1) Buzzer
2) AC output
6. Alarm Display : Upper limit or lower limit setting value blinks
7. Moisture Content
Correction Functions : 1) Temperature Correction (manual dial setting)
2) Wood Type Correction(Switchable between BROAD and NEEDLE)
3) 0 ~ +50% Correction (in 5% increments)
8. Display : Large LED digital display
9. Serial Interface : RS-232C standard
10. Power Supply : AC 100, 120, 220, 240V, 50/60Hz
5. Specifications

0401 • KO • 0201 • 010