finding value of emitter bias resistor

Discussion in 'Electronics Resources' started by thampiverghese, Mar 11, 2014.

  1. thampiverghese

    Thread Starter New Member

    Mar 10, 2014
    3
    0
    I am trying to repair an Ecolite.I found that it has a MMBTA42 as oscillator for wireless.The grounding resistor is open.How do I find the value to replace it?No info available on circuit. It is a 276 V system.When I arbitrarily substituted a 10K resistor it worked . But how do I know that is the correct value? Please help.Thanks.
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,041
    3,243
    Unless you have a circuit schematic it would be difficult to know what the correct value is.
     
  3. thampiverghese

    Thread Starter New Member

    Mar 10, 2014
    3
    0
    Thanks.There is no info available on the schematic.All components are SMT. Color coding or values are not written on resistors.ID of transistors,diodes and capacitors are available. This is almost like reverse engineering.
     
  4. thampiverghese

    Thread Starter New Member

    Mar 10, 2014
    3
    0
    Here is the circuit.I am trying to find the value of R3.
     
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