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berniedd

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Posts posted by berniedd

  1. Audioguru is right about the PIV of a rectifier should be higher than the peak inverese voltage of the AC wave it is connected to. Please note that in a half wave rectifier circuit WITH A CAPACITOR to act as an energy storage device to smooth out peaks and valleys in the rectified voltage, the PIV of the rectifier must withstand the peak voltage of the AC  wave PLUS the voltage stored in the capacitor. This is because in the next half wave of the AC where the rectifier is not conducting, the total reverse voltage impressed on the rectifier is the peak of the AC reverse voltage which is now in series with the charge stored in the capacitor (minus the small forward conducting voltage drop of the diode rectifier) .

  2. I'm just an electronics hobbyist,not a service tech. Can anyone tell me where I should start troubleshooting my eMachines CRT monitor? It shows a slight out of focus at the bottom right of the screen and there's also a slight "ghosting" with an orange color of a part of any object displayed there. For example, any icons at that part of Windows' task bar exhibit an orange smudge of their borders to 1 mm beyond to the right and below their borders. The problem used to start only 15 minutes after turn on, but now it's present all the time. Other than that, the monitor is fine. Thanks for any help guys.

  3. Hi all. i'm troubleshooting my CRT monitor and need a schematic to go. I think it's the jungle IC (STV7778) but I gotta check out other components before I replace that 42-pin chip. Symptoms: Loss of vertical sweep (horizontal line across screen) that quickly returns to normal. Later this transformed into a vertical and horizontal shrinkage of the image, accompanied by decreased brightness. It's intermittent and sometimes returns to normal, sometimes it doesn't. I've already resoldered all cold joints. Still no dice.

  4. Hi all. i'm troubleshooting my CRT monitor and need a schematic to go. I think it's the jungle IC (STV7778) but I gotta check out other components before I replace that 42-pin chip. Symptoms: Loss of vertical sweep (horizontal line across screen) that quickly returns to normal. Later this transformed into a vertical and horizontal shrinkage of the image, accompanied by decreased brightness. It's intermittent and sometimes returns to normal, sometimes it doesn't. I've already resoldered all cold joints. Still no dice.

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