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  1. the power supply comes with overvoltage protection, why it is still havin AC noise?
  2. oh..thanks your explain. so a good supplies will have a good capacitor also...
  3. what is the relationship between freq and V? does the freq really play a big role in power supply/electronics board. I got a lab test that require me to use a module to adjust the freq form 40 to 70 Hz, then observe the board (on /off). But i found that the board still can power on when i tune to 2Hz ONLY!!! and,another test is to adjust the voltage from 100 to 240V.
  4. so, if i want to enter the time for those voltage to power up my mobo. which spec i should refer to, the motherboard or power supply?
  5. need to conduct DC margin test using Agilent MAINFRAME ( have +5V,+3.3V,+12V,-12V,Power GD,+24V modules). then take out the power supply from my motherboard, connnect those modules to my board ,simulate the power supply condition. But the staff told me to calculate or figure the time for those AC voltage.... power sequence for the board to make the board fully function. But does the power sequence really important? it seems the interval time is only <20miliseconds.. Can i know whats the theory inside?
  6. oh i see. thanks. but,may i know whats the theory inside the power supply series,parallel and independ mode?
  7. I have a motherboard, it can power up by 5V. But i found it the only way i can power it and boot into windows is using parallel mode (master must in CV,slave in CC).If i want to see the current flow, then i need to sum the readings from master and slave. If i use indepent mode (Master:CV) to 5V, it will auto restart when RAM shadows finished.Cannot boot into windows. Can anyone here explain to me why???
  8. I saw the spec of my cash drawer. Is 12/24 selectable port. Whats the difference between 12V and 24V? How do I switch it? and test out it? PS: Sorry if i ask a noob question.
  9. Anyone here work as test engineer in computer/related area? Any website / books recommend to do testing job? As i am noob and newbie, need some guidelines. thanks.
  10. Sorry,one noob question: where should i point at the board to see the waveform, n check the phase?
  11. I have no idea on the audio test by using oscilloscope. Example: I play a music, and i use volume control to adjust the left and right volume. (Windows Audio/Sounds Properties) How to use the scope to verify whether the volume that i adjust is accurate. Anybody here, Pls help me. Thanks a lots.
  12. sorry, i am quite confuse now. OK. Now i have a UNIT A which has 2 port, one line in port, one line out port (audio jack). Unit A has an internal left and right speaker. 1) If i have an external speaker to test the unit audio functionality, which port should i connect it? 2) If i have an audio cable now, and i want to play my PC music on the UNIT A's internal speaker, which port should i connect it?
  13. So, if i connect an external speaker at unit A, that port which I plug is "line out" port. Then the "line in" port is when i play music at my PC,then i use audio cable to connect my pc to the unit A, to play the sound at that unit A. Am I correct?
  14. I am doing testing job currently. While i looking at specs, quite confuse witht he word"line in" and "line out" port. May somebody here briefly explain to me. Thanks a lots!
  15. Does anyone here experienced make their own LVDS and backlight cables for LCD panel? I want to reconfigure my LVDS cable output because the connector is not campatible with my motherboard. What i should do? I have the datasheet for the panel and my motherboard LVDS pin out interface.
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