help with reflow unit

Discussion in 'General Electronics Chat' started by lokeycmos, Mar 31, 2013.

  1. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    432
    7
    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:

    http://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!
     
  2. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,392
    1,606
    Last time I used my hot air pencil I forgot about the magnetic holder it needs to be in to start, does yours have one?

    If it's not something simple then it's a lot of grunt work if you don't have a schematic to follow.
     
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,998
    745
    Follow the heater wires back to the pcb, i bet they go to the Triac {on the heatsink top right pcb} and {opto coupler white 6 pin chip Moc3041}



    There is an LM358 dual op amp that will be the thermostat, prob using a thermocouple in the heating element also.
     
    Last edited: Apr 1, 2013
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