Replacing Bad WEP898D Heater Gun (SMD Rework Station)
It is not easy to replace a bad heater gun from a solder station when there is only a direct cable connection without any connector plug. Also because the cable here uses all 8 internal wires and there is no standard in the wiring color code. Any new hot air gun will most likely differ in color code for the wiring. But there are a few certainties we can depend up on. For one thing will the thicker wiring most certainly be used for both the heater wires, and one thicker wire for the safety E_GND connection to the metal outside of the nozzle. And in these heater guns there is a mutual gnd connection for both the Handle switch and the Temperature sensor. So they share one common ground and so they together are only 3 wires. Also the ohmic resistor value of the temp sensor is very low compared to the heater coil. Only just about between 1 to 3 ohm. And the heater gun value is inbetween about 70 to 80 ohm depending on what solder station and what wattage is used.
The Handle wire is connected to a magnetic sensitive contact, a glass reed contact switch, that detects when the gun is put back on its station holder. And in this WEP 898D+ hot air & solder station a 24V DC Fan is used in the gun handle to blow the hot nozzle air out. Older hot air stations still used a large air pump in the station and a long teflon tube to blow air through out to the gun with the electrical wiring inside the tube.
This was already the second time that my shop owner friend had a bad heater gun cable after many repair jobs. And again this new ordered heat gun used completely changed colors for the wiring. And fixing the defect heat gun by simply replacing the broken wires in the old cable is just waiting for the next issue to happen. So my friend had ordered a complete new heater gun that also had a 8 pin Din like connector. But he forgot to also order a matching chassis part to upgrade his station for more easily exchanging the cable the next time his heater gun cable would cause new problems.
In this case he had ordered a 858XB heater gun which I had to examine thorougly before I could cut the 8 pin plug and connect all 8 wires to the right WEP898D+ mainboard connector pins.
A plug that probably was glued to the new cable and couldn’t be removed other than by cutting it off.
Above photo shows the old YH858-3V3 heater gun pcb with the old now defect cable we need to replace. Below picture of the internal connectors was made after all old cable wire connections and their colors were checked.
Next picture was made after examining the new 858XB heater gun (pcb No 20180314) replacement with the 8 pin connector plug we removed to connect all wires direct onto all WEP 898D+ mainboard connectors.
In above picture I only used purple for a white wire that is hard to draw on white paper. Take notice that the temperature sensor is also placed in close position to the heater element.
As we can see we used all 8 wires : 2 for the heater element, 2 for the 24V DC Fan, 3 for the Handle switch and the Temp sensor (mutual GND connection!) , and one VERY important safety E-ground wire connected to the outside metal nozzle construction of the gun.
And after this already second repair on this WEP898D+ station my friend could again fully use his as new fixed hot air station. The first time we didn’t need to replace the 8 wire cable but we only needed to replace the heater gun with a new heater element which was much easier!
After this I also checked the wiring of my own hot air solder stations to make sure it is documented in case a fast and easy repair is required in the near future. My good old Gordak 952-A with teflon tube,
and also following my Atten AT8586 2 in 1 Hot air and solder station, and also shown data of my Aoyue 937+ station. Also some info on the often used 5 pin wired 24V/50W solder iron.
Fixing hot air stations, solder irons and completely replacing those heater guns should be no big problem anymore after reading this. But probably always look for a good heater element that matches the wattage of your hot air station and uses the same Fan voltage!
And if you do replace the cable on a unit without any Din plug connector as was the case in this repair, maybe better also order a matching chassis plug to upgrade your hot air station with. Because my friend failed to order one although I told him it would be better to add one now to his unit.
It will save you a lot of extra work and time in case you also have to replace the complete heater gun with all 8 wires attached the next time.
Albert van Bemmelen, Weert, The Netherlands.
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Note: You can read his previous article on DIY- Make A REAL Universal 20 Pins SMD To DIP Chip Adapter That Does Not Exist