Search:

Type: Posts; User: hafrse

Page 1 of 5 1 2 3 4

Search: Search took 0.01 seconds.

  1. [SOLVED]Closed: Converting balqnced supply +12 0 -12 V audio amplifier to 0 +12 supply

    Hello,

    I have a schematic of audio amplifier using balanced power supply +12/-12 volts, in my application I only have +12V, I know that I need to add coupling caps on inputs and outputs , aslo I...
  2. Closed: Re: Adding CCFL light or LED backlight to a 6 digit/7 segment LCD display

    Thanks, I will try that :)

    - - - Updated - - -



    Thanks, will not take away the backside since I only have this display to work with.
  3. Closed: Adding CCFL light or LED backlight to a 6 digit/7 segment LCD display

    Hello,

    Is possible to add CCFL light or LED backlight to a 6 digit/7 segment LCD display which has no backligt from the beginning? I have seen some article about doing that many years ago (could...
  4. [SOLVED]Closed: Re: Loud POP sound when swicthing audio filters i a vintage audio amplifier

    Problem solved: the new electrolytic cap to replace the C10 on the filter board was bad!replaced it with another one, all ok now.
  5. [SOLVED]Closed: Re: Loud POP sound when swicthing audio filters i a vintage audio amplifier

    Correct, that is the input #4 to the filter board, checked, it is -0.6V , the outputs #2 and #3 is 0V after the coupling caps. But why this issue clears after about 2 min ? I
  6. [SOLVED]Closed: Re: Loud POP sound when swicthing audio filters i a vintage audio amplifier

    Hello,
    Thanks, I replaced all the electrolytic caps on the filter board: C3, C10 and C4. Now I only have a loud pop when switching between FLAT postion and Max. Loudness position, switching between...
  7. [SOLVED]Closed: Loud POP sound when swicthing audio filters i a vintage audio amplifier

    Hello,

    I am trying to repair a nagra DSM audio amplifier, it pops when switching the audio filter selector switch S2. Checked for coupling caps on the filter board, no short circuit there. Any...
  8. Replies
    27
    Views
    2,406

    Closed: Re: Spurs visible on my spectrum analyzer

    Unfortunatly discovred more spurs at 300khz (see picture on previous post) on specific YIG frequncies (no generator signal involved here ), the 300Khz spurs will not change if the power supply out...
  9. Replies
    27
    Views
    2,406

    Closed: Re: Spurs visible on my spectrum analyzer

    You are right, I also discovered other spurs at 300Khz from mesured CW at specific input frequencies, I suspected the YIG, I used another spectrum analyzer to check the YIG output at 0 span and no...
  10. Replies
    27
    Views
    2,406

    Closed: Re: Spurs visible on my spectrum analyzer

    Hello,

    If I tune the spectrum analyzer at 0 hz , it shows a peak of about -16 dbm, that is normal for most of the spectrum analyzers to show that peak. I have nothing connected to the analyzer,...
  11. Replies
    27
    Views
    2,406

    Closed: Re: Spurs visible on my spectrum analyzer

    Yes, the same problem when tuning to the analyzer 0 hz peak (without any input signal) or any other frequency from an external geberater . The 30 Mhz is the cal signal supplied by the analyzer....
  12. Replies
    27
    Views
    2,406

    Closed: Re: Spurs visible on my spectrum analyzer

    Hello,

    Sorry, I meant 50 Hz spacing from signal carrier. Signal carrier (CW) can be at any frequency, always shows 50hz purs at -134dbm
  13. Replies
    27
    Views
    2,406

    Closed: Spurs visible on my spectrum analyzer

    Hi,

    Spurs visible on my spectrum analyzer, please see attached picture. checked power supply lines, all are good. moved power supply from the chassi about 10 cm, all spurs gone. Any idea what...
  14. Replies
    27
    Views
    2,406

    Closed: Re: Suspected high ripple on SMPS

    Thanks for your reply, the picture shows a signal on 30 Mhz with spur at 50 Hz, it happenns also in any other frequencies, 10Ghz, 10hz, etc..., even without any signal on the 0 hz spectrum analyzer...
  15. Replies
    27
    Views
    2,406

    Closed: Re: Suspected high ripple on SMPS

    Is there any way to reduce the electromangnetic radiation from the smps by shielding ? can I use steel plates as shielding?
    Thanks
  16. Replies
    27
    Views
    2,406

    Closed: Re: Suspected high ripple on SMPS

    I also isolated the SMPS in its place from the chassi by paper, spurs still there, it is radiated noise. So how can I fix that problem? thanks
  17. Replies
    27
    Views
    2,406

    Closed: Re: Suspected high ripple on SMPS

    Hello,
    It was a meauring error from my side, there is no electrical ripples
    as I stated in my earlier post, I moved out the SMPS from the chassi, and there are no spurs in the display of the...
  18. Replies
    27
    Views
    2,406

    Closed: Re: Suspected high ripple on SMPS

    I have now moved the smps from the analyzer frame (but still electrically connected) and all the spurs dissapeard!

    It seems that the smps is radiating /modulating magnetic/mechanical noise...
  19. Replies
    27
    Views
    2,406

    Closed: Re: Suspected high ripple on SMPS

    Hello,

    You are right, doing as you say shorting the probe and measure at 12v giving lower amplitude an same trace shape, about 0.2v insted of 0.628v , but not sure if that is ok, I am not on...
  20. Replies
    27
    Views
    2,406

    Closed: Suspected high ripple on SMPS 0.628v at 12v

    Hello,

    I have a problem with an analyzer which shows spurs from CW 50hz (highest amplitude) , 15hz,350hz,etc... suspected the power supply and checked one of the voltages -12V and there is a...
  21. Closed: Re: 100 Hz buzzing sound from switch mode power supply

    Hello,

    I have a transparent varnish spray normally used on cars to protect the metallic colour when making a new paint, will that be ok ?
    Thanks
  22. Closed: Re: 100 Hz buzzing sound from switch mode power supply

    Hello,

    Since there is no electrical failure with this SMPS , How can I "fix" the HF transformer and the chokes based on the picture of the SMPS above? what type of adhesive I should use on the...
  23. Closed: Re: 100 Hz buzzing sound from switch mode power supply

    Hello,

    I have tried to listen through a stethoscope , the aluminium chassi , IF1 + IF2 (input filter chokes) , L1 , L2, and T1.

    Here is the result:

    The chassi/PCB near the primary side has...
  24. Closed: Re: 100 Hz buzzing sound from switch mode power supply

    Hello,
    Thanks, I just measured around c9+c10, the ripple is not more than 21v even with the highest load (goes up to 22v).
    i can hear the buzz from choke L1 (loudest) and even from T1 slightly if...
  25. Closed: Re: 100 Hz buzzing sound from switch mode power supply

    Hello,

    There are 2 line filter transformers, LF1 and LF (2 similar white l) . And there are 2 transformers L1 (white) before the rectifier bridge and L2 (yellow) after the rectifier bridg
    The HF...
Results 1 to 25 of 101
Page 1 of 5 1 2 3 4