Why does the thermometer show a lower temperature than the set temperature?

The following cases could be a cause of the above problem.

Case 1.The measurement method is not correct.
Case 2.The thermal sensor became deteriorated.
Case 3.The battery in the thermometer is almost consumed.
Case 4.The soldering tip, enclosure pipe and nut were oxidized.
Case 5.The tip shape is changed, after the fine temperature adjustment (changing offset value or CAL adjustment)

If any of the above is not your case, contact the shop you purchased the product from or the local HAKKO sales representative/distributor for repair.

Case 1.
The measurement method is not correct.

If you measure the temperature incorrectly, you cannot obtain the correct temperature value, and sometimes you have a lower temperature than the actual one.
Measure the temperature with the correct method.

Measuring method of a tip temperature

Remove solder stuck on the tip before measurement.
Apply new solder to the tip.
Place the tip on the measuring point and feed solder on the tip.
How to apply the tip to the measuring point of the sensor
- Place the tip on the measurement point horizontally.
- Place the central part of the pre-tinned tip end on the measuring point of the sensor.
- Make a measurement placing the tip end on the sensor gently.
Please do not press the tip end to the sensor too much not to break it.

OK

No Good

( image of 191-212 discontinued )

Please do not move the tip until the display shows a stable temperature.

Measure the temperature in a place where there is no airflow from the air conditioner or the like.

Example of the measurement method according to tip shapes

B type, I type, D type
<Measure the central part of the pre-tinned tip end>

BC type, C type(including the tips with tinned on cut-surface only)
<Measure the cut-surface>
( image of FG-100 discontinued )
Read the value displayed. (It shows 376℃ in the photo.)

( image of FG-100 discontinued )
Repeat the above procedure (1 to 4) to find the highest temperature.

Hakko rules it as the correct temperature, which is the highest after measuring the same tip several times.: Soldering tips with slim shanks such as shape-I or shape-1C could be lower than the actual temperature, and it is necessary to read the value displayed after spending enough time until it becomes stable.

Case 2.
The thermal sensor became deteriorated.

If the sensor has deteriorated due to corrosion by solder, the measured temperature could be lower in some cases.

Timing of the sensor replacement

AS5000 :

Approx. 1,500times
191-212 (Discontinued):

Approx. 50times

Deteriorated sensor — ( image of 191-212 discontinued )

Case 3.
The battery in the thermometer is almost consumed.

If batteries are low on power, the display may show errors.
Replace it with a new battery before measuring the temperature again.

Example of display when the battery becomes low

In the case of FG-100B / FG-100 (Discontinued)

When the battery is low on power, the 'B' mark circled in red in the photo lights up. If the battery becomes further lower with continuous use, the icon begins to fade and disappears finally.

If batteries are low on power, the display may show errors. — ( image of FG-100 discontinued )

In the case of FG-102

When the battery is low on power, the battery icon circled in red in the photo flashes. If the battery becomes further lower, the icon becomes steadily lit. In some cases, the screen may display "Low Battery" when you power it on, and then it immediately turns off.

In the case of HAKKO 191 (Discontinued)

When the battery is low on power, the 'B' mark circled in red in the photo lights up.
If the battery becomes further lower with continuous use, the icon begins to fade and disappears finally.

Case 4.
The soldering tip, enclosure pipe and nut were oxidized.

It happens that you would obtain lower measured temperatures due to oxidation of the tip, enclosure pipe, and nut.
Replace them with new ones.

HAKKO 907 whose parts are oxidized — HAKKO 907 (discontinued) with oxidized parts

Case 5.
The tip shape is changed after the fine temperature adjustment (changing offset value or CAL adjustment)

The length and weight vary depending on the tip shape. If the tip shape is changed, it may cause the temperature to become lower or higher in some cases as the themal capacity is changed.

Make fine temperature adjustment (changing the offset value or CAL adjustment) with the tip you use.

Setting of the offset value

Calculate the offset value from the difference between 'Tip temperature' and 'Set temperature' and the current offset value, and input it to the station.
If the tip temperature is lower than the set temperature, input a positive offset value to the station. If the tip temperature is higher than the set temperature, input a negative offset value.

(A setting example when set temperature : 350℃, tip temperature : 320℃, current offset value : +10)

Calculate the temperature difference with tip temperature and set temperature.
320℃　-　350℃　＝　－30
Calculate a new offset value for input with the current offset value and the current temperature difference.
＋10　＋　(－30)　＝　－20
Input the new offset value to the station.。

The input method of the offset value differs among the models. Please refer to the instruction manual.

CAL adjustment

Adjust the CAL knob using a tool like a screwdriver.

Please turn to the right to increase the temperature and to the left to decrease it.

If there is any problem other than above mentioned or you cannot fix, please contact the store of purchase or the Hakko official distributor for solution.

Why does the thermometer show a lower temperature than the set temperature?

Case 1. The measurement method is not correct.