HAKKO 920 Soldering Iron User Guide
- June 17, 2024
- Hakko
Table of Contents
HAKKO 920 Soldering Iron
INSTRUCTION
-
Bad Cord : Check the continuity between the tree prongs on the power cord and the cord connections on the PCB in the handle. See Figure 1. If the resistance is above 200 then the power cord is bad and should be replaced. The power cord part number is 777-014.
-
Bad Heating Element : Check the resistance between the two heater leads which is covered by the red tubing. The resistance of the heater should be between 68-760. Then check the resistance on the sensor leads which are covered by the white tubing. The resistance of the sensor should be between 135-185’2.
If the resistance between either set of leads does not match the above resistance, then the heating element is bad and should be replaced. The heating element part number is (See Replacement Parts). -
Bad PCB: If the iron overheats by more than 25 degrees the PCB is bad and needs to be replaced. The part number for the PCB is (See Replacement Parts).
-
Old Tip: In many cases, an old tip will not come up to the proper temperature. Replace with a new tip and check the temperature.
-
Incorrect Calibration Resistor : Check the resistance of the R 5 resistor on the back of the PCB. See Figure 2. If the resistance of the sensor in the heating element and the R 5 resistor do not match as shown in the chart below, then the temperature will be out of calibration. If this is the case, then change the R 5 resistor to match the correct resistance.
REPLACEMENT PARTS
Heater| Heating Element
IC| PC1701C
Triac| AC030GM 400V3A
RSyn| 75kQ 1/6w
RS1| 22kQ 1w
RS2| 22kQ 1w
AO| 300Q 1/6w
A1| 20kQ 1/6w
A2| 510Q 1/6w
A3| 20kQ 1/6w
R4| 20kQ 1/6w
D1| 200v 1A
C1| 10v 100uF
C2| 10v 100uF
TH| Resistance of Sensor
A5| See Sensor Resistance Chart
RESISTANCE CHART
RESISTANCE CHART FOR 918/920/921/922
TROUBLESHOOTING
TROUBLESHOOTING GUIDE FOR THE HAKKO 918/920/921/922/924 IRON
| TROUBLE | POSSIBLE CAUSE |
|---|---|
| Unit is plugged in, but it does not heat up. | Bad cord, bad heating element or |
bad PCB
The unit overheats when turned on.| Bad PCB
Iron is out of calibration.| Bad PCB, old tip or incorrect calibration
resistor.
