Aron bs-601 scope issue

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  • The_Todd
    Senior Member
    • Jul 2017
    • 66
    • Australia

    #21
    Re: Aron bs-601 scope issue

    Originally posted by R_J
    The fact that you get a waveform at all is a good sign. too bad you don't have a scope to trace the signal
    Check some of the voltages on the vertical board and see if something is missing or a voltage that does'nt look right, I see a few voltages listed on the schematic so check them first
    I do have a working scope

    Comment

    • eccerr0r
      Solder Sloth
      • Nov 2012
      • 8666
      • USA

      #22
      Re: Aron bs-601 scope issue

      Those voltages on the schematic are the PSU voltages and probably not enough to debug with. Not sure what else but to just trace things along since you have the other scope and have that signal generator (the probe calibration source). Else it is still possible to debug with a multimeter with the vpos pots.

      I'd especially like to know what the voltages are on Q21 and Q22 as you spin the vpos pot up and down...

      Comment

      • The_Todd
        Senior Member
        • Jul 2017
        • 66
        • Australia

        #23
        Re: Aron bs-601 scope issue

        Originally posted by eccerr0r
        Those voltages on the schematic are the PSU voltages and probably not enough to debug with. Not sure what else but to just trace things along since you have the other scope and have that signal generator (the probe calibration source). Else it is still possible to debug with a multimeter with the vpos pots.

        I'd especially like to know what the voltages are on Q21 and Q22 as you spin the vpos pot up and down...
        I can test that, witch pins should i test on? and do you want a voltage readout or a scope signal? and witch pots to test with?

        Comment

        • The_Todd
          Senior Member
          • Jul 2017
          • 66
          • Australia

          #24
          Re: Aron bs-601 scope issue

          Originally posted by R_J
          It looks like you should have -8 volts going to the center of the vert. position control, That shouuld change the bias on q29 and q30 moving the trace up or down. You say you have all the voltages but where did you check them? they may be at P3 but do they get to get to where they should. There are a number of coils in the voltage lines, make sure the voltage is on both sides of them and one is not open.

          Just so i dont stuff up, witch point should i test the -8? i haveonly tested voltages at the conector

          Comment

          • eccerr0r
            Solder Sloth
            • Nov 2012
            • 8666
            • USA

            #25
            Re: Aron bs-601 scope issue

            Curious as to the voltage on the collectors of both Q21 and Q22 with just one channel on, one measurement for when the vpos for that channel fully CCW and fully CW. There should be a significant difference of the voltage at that point I would guess for the two cases, ideally they should flip flop their voltages depending on which way the vpos pot is set...

            I still wonder what the voltages across D10 R80 R89 D11 D14 are. Would imagine them to be something like 12V - D10 - 17V - R80 - 90V - R89 - 108V - R89 - 114V - D11 - 115V - D14 - 120V or something like that....

            *sigh* lucky people with scopes that have schematics available... I wish my 20MHz scope had schematics somewhere. Not quite the same when you have schematics for a scope that has unobtanium ICs in them like the later Tektronix...
            Last edited by eccerr0r; 01-28-2019, 01:36 AM.

            Comment

            • stj
              Great Sage 齊天大聖
              • Dec 2009
              • 30931
              • Albion

              #26
              Re: Aron bs-601 scope issue

              some tek chips have been reverse engineered.

              Comment

              • eccerr0r
                Solder Sloth
                • Nov 2012
                • 8666
                • USA

                #27
                Re: Aron bs-601 scope issue

                U800

                Sigh. If the U800 blows in my 2465, I don't know if it's worth keeping the scope or just parting it. Someone has hacked up a workalike but sheesh, needs to run with stable gain at something like 100MHz or so, maybe more in 10x mode.

                Comment

                • R_J
                  Badcaps Legend
                  • Jun 2012
                  • 9515
                  • Canada

                  #28
                  Re: Aron bs-601 scope issue

                  Originally posted by The_Todd
                  Just so i dont stuff up, witch point should i test the -8? i haveonly tested voltages at the conector
                  Is the vertical board easy to access? if it is You can check for the -8 volts on L4, It is located next to P1, You should also be able to check the voltage on P1, Pin 2 should be -8v and pins 1 & 3 will vary when you turn the vertical position control on the front panel for channel A
                  If you can, check the voltage on D10, (J5) then R80. also D11 and D14 they are near P2
                  Last edited by R_J; 01-28-2019, 10:28 AM.

                  Comment

                  • stj
                    Great Sage 齊天大聖
                    • Dec 2009
                    • 30931
                    • Albion

                    #29
                    Re: Aron bs-601 scope issue

                    does this scope use sockets on the transistors??

                    Comment

                    • redwire
                      Badcaps Legend
                      • Dec 2010
                      • 3900
                      • Canada

                      #30
                      Re: Aron bs-601 scope issue

                      OP fixed it, open R80 43k.

                      Comment

                      • R_J
                        Badcaps Legend
                        • Jun 2012
                        • 9515
                        • Canada

                        #31
                        Re: Aron bs-601 scope issue

                        Good to here he has it repaired.
                        FROM https://www.eevblog.com/forum/repair...-amp-issue/25/
                        EUREKA!!!! Found the problem!!! R80 was an open line! replaced with 43k and well, now we have full range on vertical
                        Last edited by R_J; 01-28-2019, 02:21 PM.

                        Comment

                        • eccerr0r
                          Solder Sloth
                          • Nov 2012
                          • 8666
                          • USA

                          #32
                          Re: Aron bs-601 scope issue

                          Dang, I told him to check the voltage across that voltage divider through R80 in post #8 ... oh well, at least it's fixed now.

                          Comment

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