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Late 1960's BFO

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  • #31
    Originally posted by jap View Post
    no comment.
    J.
    LOL! Come on, cut me some slack! I'm not a PCB genius like some of you guys.
    This is the first time I've done anything like this in 20yrs! I started drawing lines after I oriented everything and listed values. I was so tired by then, I KNEW I was going to make a ton of mistakes. I've never tried this on a computer before.
    I did take out Q1 and checked it as an NPN. I'm confident that it's oriented correctly but my connections have some definite mistakes.
    Corrections coming when time allows.
    Like I said, some of you guys are so sharp, you can probably finish before me.

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    • #32
      Hi Skippy
      Thanks,of a clear picture of the bottom of the copper lines,Any one can give you a schematic from pcb.
      best time
      j.

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      • #33
        Had a little time to add and fix some stuff.
        My lysdexia makes it harder.
        I swear Q1 checked out the same as a 2N2222A!
        Attached Files

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        • #34
          Hi HECTOR
          Examine the image of any mistakes I hope you correct any errors.
          best time
          j.
          Attached Files

          Comment


          • #35
            Thanks Jap!
            I have a 10hr day tomorrow, then I'll be away from my computer for a few days.
            Are we sure those aren't NPN's? I changed them due to outside influences.
            I know how to ID EBC and PNP/NPN (I thought) but I'll take it out again to be sure, if nobody else is. My knowledge is very basic and rusty.

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            • #36
              Here is some basic testing .

              http://www.wies-hs.eu.dodea.edu/Cour...c/EleTstGD.pdf

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              • #37
                Hi HECTOR
                If you know the numbers written on each TR ,Q1.2,3,4 So there is no problem of kind PNP/NPN - noticed that the Q1.2,3,4 Japanese type BCE.
                -Q1 the same as a 2N2222A in type NPN not in BCE.
                -I hope you correct any errors in image.(There are more than mis-)
                -What are the specifications of the coil?
                best time.
                j.

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                • #38
                  There are NO markings whatsoever on the transistors. What I thought was white paint underneath was epoxy. The (gold plated, oooh) leads are off center. With the device upside down and the point of the triangle facing down, it goes EBC from left to right. I got an hfe reading of 25 compared to 35 for 2N2222A. I don't think that you can get a reading with the pins in the wrong holes. I also did a manual bias check. Could have made an error when I went from one Q to the other.
                  Thanks you guys!
                  Talk to you in a couple days

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                  • #39
                    Hi HECTOR
                    What you did is true - then are n b n - the difference between the two readings 25 compared to 35 for 2N2222A is between the HFE between the two numbers and the biggest best - must be estimated in advance time in manufacturing.
                    best time
                    j.

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                    • #40
                      Although there are probably mistakes and missing values, the connections are "finished".
                      Now that i have a finished version, I can compare section by section to weed out errors.
                      Attached Files

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                      • #41
                        A few details that need attention: C9/C10 seem unusually connected. R12,R14 have odd values. R3,R5 connections odd, they are shown in parallel. There appears to be a missing connection from battery +9V to the audio-amp circuit, at the end of the transformer primary winding, I guess. It's worth adding the 0V connection to the 10mm transformer can to the circuit.

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                        • #42
                          Hi Skippy
                          correction true.
                          (There are more than mis-)
                          J.

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                          • #43
                            Although the 10mm transformer will need removing from the PCB to assess it properly, it would be worth doing a continuity check on it in-circuit, to help eliminate some winding configurations. These transformers have a pin numbering system that is like DIL I.C's, so this one will have pins 1,2,3,4,6

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                            • #44
                              At least I saved a jpeg version to reproduce all my work tonight. I mistakenly hit "NO" when it asked me if I wanted to save
                              Never even checked to see if it would run without any errors.
                              I know it's getting VERY close.
                              Some of the cap #'s are not familiar.
                              Note ferrite coil operating freq 662KHZ (center) Only guessing transformer symbol for ease of pinout ID. Output sine wave is on the top third pin to the right. Pre amp sine is top left
                              Attached Files

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                              • #45
                                Top side of L1 should go between C9&C10! Not C6.

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