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  1. dorke

    Amplifier blows power fuse

    If it is a home theater amp it should have 5 channels or more(how many are there?) so, If there are only 2 then these aren't them. Could you post a picture showing "all the amp parts". What is written on the 5 pin black devices on the heatsink in post#3 ? they could be the PA ICs.
  2. dorke

    Amplifier blows power fuse

    Check the final power transistors in diode test mode. There is a good chance some are shorted out.
  3. dorke

    Identify corroded diode?

    A few notes: 1.From your description of the board it has to do with safety at construction sites. If I were you I wouldn't touch it ! because if any damage would happen to the crane it may literally fall on your shoulders, more than that, if anyone will be injured it will be a burden you don't...
  4. dorke

    Chosing the Right Tweeter

    I think it is very important to find out why the tweeter has blown. It is absolutely crucial to find out that it isn't the AMP that caused the problem. Another thing is the difference between music power and R.M.S power. What kind of speakers do you have brand and model? Can you post some...
  5. dorke

    Chosing the Right Tweeter

    That is a lot of power. Which brand are the speakers? The obvious thing to do ,would be getting the same type of tweeter.
  6. dorke

    DSP/Amp Problem (Reversed Polarity)

    Only thing I can think about is maybe the P.S used has a fold-back current limit. I would try it in the car without an amp-meter as you suggested.
  7. dorke

    to short DC terminal by using 5 sec delay and when ac source apply

    1.Usually? who says? there are many ways to skin a cat... 2.Wrong,there is no 5sec delay(yet).
  8. dorke

    Chosing the Right Tweeter

    This is a fairly complicated issue. I would say it is an acoustic issue more than an electronic one. It depends on so many things like: how would you like your system to sound,what kind of music do you play. what power ratings should your system have. What size should it have. What size of...
  9. dorke

    Electronics Talk - interesting interviews and shows

    I hope this list will grow and include many more interesting Electronics persons videos. Enjoy. Paul Horowitz - co-writer of the book The Art of Electronics. Jim Williams - Legendary Analog designer and Application Guru. Bob Pease - Legendary Analog designer. Hans Camenzind - the inventor...
  10. dorke

    Electronics Talk - interesting interviews and shows

    dorke submitted a new resource: Electronics Talk - intresting interviews and shows - Interesting videos with/on Electronics Legeneds Read more about this resource...
  11. dorke

    Need help finding brand name.

    Without any writing on the connector it would be difficult. I guess it would be a Chinese brand. You can search the known brands like: Molex JST etc.
  12. dorke

    to short DC terminal by using 5 sec delay and when ac source apply

    Well, Here is one simple solution,using a 220v ac relay. I will leave the delay issue for you...;)
  13. dorke

    a couple of composite video questions

    Beyond the issue of added noise that AK mentioned, there is the issue of the video signal propagation (which has a bandwidth of about 5.5Mhz for PAL) through the transmission line(i.e coax). The coax should have a 75 ohm impedance,otherwise there will be reflations which will totally distort...
  14. dorke

    a couple of composite video questions

    The minimum needed is a signal+Gnd return wire. It is essentially a transmission line created of both wires-will not work properly with just one. Isn't there a coax terminal at the "boxes" ?
  15. dorke

    a couple of composite video questions

    1. No, it doesn't create a ground loop. 2.You can not use a single wire like the yellow one in your 2nd drawing. The composite video needs a 75 ohm coaxial connection. Using it in any other way will degrade the signal. Absolutely not recommended!
  16. dorke

    Old NB O² Sensor Signal Enhancer

    First thing that pops out is the fact that both op. amps inputs are biased incorrectly. In the way you did it will only work if you use a dual ±P.S. Since you are using a single P.S you need to bias the inputs to be 12/2=6V that would be your signal reference "GND". So the ground of the LM7812...
  17. dorke

    to short DC terminal by using 5 sec delay and when ac source apply

    Welcome to EP, I can not understand what your are saying: "should enable and turn off", what do you mean by that?
  18. dorke

    Digitally monitoring end of line resistors

    Well Pascal, Here is a possible solution for you: Using 2 lines of the D1711 A and B instead of the current single line A. note: line A can act as a short indication(active low). line B can act as the closed/open indication. but you are free to use them as you like.
  19. dorke

    B & O Penta amplifier repair and Tr equivalents

    Testing a JFET: Your T3 is an N-channel JFET. Test it like you test an NPN-BJT in diode test mode. i.e Base replaced by Gate . you should get Froward diodes when gate is + lead (G-D,G-S). and Backwards diodes when gate is - lead (G-D,G-S). The only difference between JFET and BJT is : same...
  20. dorke

    Reading LCD display

    At least post a photo of the LCD front and back.
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