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  1. L

    0-30V Stabilized Power Supply

    i see.... right now the LED is light up after i change the capacitor but without U2 and U1 in place,  still looking in local store here.
  2. L

    0-30V Stabilized Power Supply

    after browsing old posting. i found that picmaster pcb drawing has a fault on C10 or C3 if using audioguru schematic it is + and - of the capacitor is backward in the pcb. and i found mine was backward and it is now shorted maybe this is the cause of the U1 and u2 blew?
  3. L

    0-30V Stabilized Power Supply

    ok... i have to wait the new op-amp from digikey. will inform you later. btw can i use opa445? i have few in the drawer. thanks
  4. L

    0-30V Stabilized Power Supply

    what should i do? when P2 set to 3.8V the ZD 10V and op-amp is impossible to touch i think it will blow too if i set to long.
  5. L

    0-30V Stabilized Power Supply

    hi all specially Audioguru, i build with mc34071, 24VAC transformer and picmaster PCB layout... yesterday i blew two op-amp U1 and U2. i trace from u3 when i turn P2 until 3.4-4.0V on R18 u3 and ZD 10V become very hot. and i think when those op amp blew i set the P2 more than 3.4V.... what's...
  6. L

    0-30V Stabilized Power Supply

    just replace R2 with higher watt, 5W and C2 with branded one still -2.1V with full load. output still stuck at 28.5V. R7 because i have difficulties to find one so i use 4 1Ω parallel is it problem? thanks
  7. L

    0-30V Stabilized Power Supply

    without load (remove all ICs) it is -5.6V. with load (all component) except Q1, R13, R14 is -2.1V thanks
  8. L

    0-30V Stabilized Power Supply

    so i just remove the Q1, R13, R14, R15, D10 correct? is it in D7 i have to measure the -5.6V? thank's
  9. L

    0-30V Stabilized Power Supply

  10. L

    0-30V Stabilized Power Supply

    Hi audioguru, just finished soldering all the component using old schematic + old pcb layout with OPA445 and 25Vac 6.25A toroid. but there is a problem the output can not be adjust? and the U1 is slightly hotter than the others. do you have test point what the voltage should be at that point so...
  11. L

    0-30V Stabilized Power Supply

    ok Thanks audioguru.
  12. L

    0-30V Stabilized Power Supply

    hi audioguru, i have opa445 on hand right now, so which schematic should i use? thanks,
  13. L

    0-30V Stabilized Power Supply

    Thanks audioguru for the answer
  14. L

    0-30V Stabilized Power Supply

    hi all, is it possible to use LT1491 for the op-amp? coz i have few on my drawer thanks,
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