help with reflow station

[lokeycmos]

the other day my yihua 8508D heat gun stopped working. the display comes on,but no heat or air flow. I have verified that the air pump works outside of the unit. there is some info on the unit here:



https://www.alibaba.com/product-gs/216305021/YIHUA_8508D_diaphragm_pump_Hot_Air.html



it says that the heating element is supposed to be 90 ohms, but im measuring 20 ohms. I removed the connecter where the heating element connects to the circuit board. I measure 120v across the two connectors,but when I reconnect the heating element I only measure a few volts AC.



im thinking that there may be more than one issue. does anyone have any advice or pointers for me? also, anyone know where I can get a schematic for it? thanks!

 

[alec_t]

the heating element is supposed to be 90 ohms, but im measuring 20 ohms.

Is that with the element disconnected from everything? If so, the low resistance may have caused excessive current flow and blown a fuse or burnt out any switching/control device.

Edit: If the blue cube next to the air pump connector is a relay, check the continuity of its coil.
The adjacent BT136 transistor is also a possible failure candidate.