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  1. dorke

    PA mixer / amp repair help

    Yep, I meant no smoke.... I don't think the USB scopes are worth the price(they have poor resolution), For about 100$ you can get a Tektronics 465B( I use one) or 475 etc. working analog scope. For audio, I have used the "Visual Analyzer" a free "software scope". It is great for...
  2. dorke

    PA mixer / amp repair help

    Well, R34 value is another deviation from the schematics. I would go with the 0.47 anyways. Forgot to ask if you checked D15,D16. In general, would you say that the deviation from the schematics is just in values of some parts or that the board is actually different from the schematics? One...
  3. dorke

    Hitachi desk fan capacitor replacement

    Nice to hear :)
  4. dorke

    PA mixer / amp repair help

    In theory the Tr's should be fine as a "beefier replacement". The question is where did you buy them from? if on Ebay(and alike) they could be fakes! If that is the case(Ebay), I suggest you cut the burned ones open and compare to the photos in the following link...
  5. dorke

    PA mixer / amp repair help

    First thing to ask is what kind of noise? Hum(line-50/60Hz buzz),White(shshshshsh type),Crackling,other? In general,you can get noise if J1 is disconnected ,because the input to the PA is floating. Most probably ,It would be the Hum type. If you disconnect the cable J1-J4 at the mixer side you...
  6. dorke

    PA mixer / amp repair help

    "drawings i have and that they are not identical to my mixer" Are the differences small or major? The grounding scheme seems to be separated: chassis and signal ground. with very specific places they are joint together. About the noise issue, I think you should first determine if it comes...
  7. dorke

    Pot Core dismantling

    Duke and Martin, We share a common disease... I have a room full of that kinda stuff. :cool: Duke, I think 100 C should do the work, hopefully without damaging the plastic.
  8. dorke

    Transistor or temp switch attached to heatsink? Crate PA-600 repair

    What is wrong with the PA-600? Photos can always help, same goes for schematics .
  9. dorke

    Pot Core dismantling

    The halves are glued together. The ferrite is very fragile and would break easily into fragments if "hammered" . I think the best way is heating the glue to its melting point and taking the halves apart(100 C or about ,with gloves or pliers-very light grip !) You can heat with a hot-gun,an...
  10. dorke

    Help with FPC contacts

    Agree, If not found,I would search JST
  11. dorke

    Help with FPC contacts

    Old steve, yep, googled it. you beat me to it,a visit to the wc room :)
  12. dorke

    Help with FPC contacts

    Maybe here,page 22 http://www.servoconnectors.co.uk/pdfs/2008Product%20Guide.pdf
  13. dorke

    Fixing motorcycle LED turn signal - What size / Type LEDs?

    "A shiny new motorcycle"...don't you have any warranty?
  14. dorke

    Dell Lcd backlight inverter.

    Which model? A pic in the service manual could help solve this.
  15. dorke

    Help identify this please.

    Steve, It is indeed a 50V cap. The voltage(code and location) is probably the only common parameter to various manufactures. The first letter is the manufacture id. ,the last can be dielectric type. See an example from "Kemet"
  16. dorke

    Stereo power amp - odd fault

    Nice to hear you solved the problem :)
  17. dorke

    Can someone ID this Transistor ? Offer Equivalent part ?

    You can try this one : Infineon BCR133 in sot-23 package http://www.infineon.com/dgdl/Infineon-BCR133SERIES-DS-v01_01-en.pdf?fileId=db3a30431428a37301143f7f8a3f0288 Good Luck
  18. dorke

    Repairing a faulty SD card

    Look here it may help or here: A good free recovery program: http://www.cgsecurity.org/wiki/PhotoRec Good luck
  19. dorke

    Stereo power amp - odd fault

    Here is the diagram of the inputs(part of the service manual). As you can see: B input with a Mono plug connected (while A has nothing physically plugged into it) can drive both A and B channels with separate A and B volume control. Can you try that? If you are getting sound from A it is...
  20. dorke

    Diode Identification Help

    I would go for a higher voltage,same as the cap rating. Maybe 1N4937 not a schottky but a fast rectifier http://www.vishay.com/docs/88508/1n4933.pdf
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