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Klemt Echolette S

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  • #91
    Hi, the rubber tube mounts are a pain, I usually replace them with small rubber grommets(the ones that allow wires to pass through metal chassi) but the lower tube Ro3 is probably beyond your competence. There is a small eyelet inside the rubber mount through which the retaining screws pass which is required when fitting a replacement grommet.
    I remove the screws and eyelet, then pull out all of the rubber mount and fit the grommets using contact glue to keep them in place. The grommets won't be as flexible as the original rubber but I haven't experienced any issues.
    The biggest problem that I usually encounter when doing this type of repair is the damage to wiring etc that I cause because of the limited access. So be careful!
    The light bulbs are screw type bulbs and their sockets are held in place by a single screw which you can see on either side of the switch bank. The bulbs are a 7 volt variety but can be replaced with a standard 6.3V type.
    The motor noise could be caused by a dry bearing on the bottom of the motor. This can be accessed by removing the small white retaining plug after removing the internal circlip. I use graphite or molybdenum grease. Resetting the screws which hold the motor to the chassis may also be beneficial as sometimes these have been un-evenly tightened.
    Have just got one of these units on the workbench for a complete overhaul, should be fun!!??
    Cheers, Mickey

    Comment


    • #92
      Hello Mickey.
      Thank you for your reply! Since my post to this thread I have looked a bit more into my unit. I found out that the noise, which I thought came from the motor, is coming from the pinch wheel (andruckrolle). The wheel has become very hard, and every time the splice on the tape is passing, it makes a loud noise. I have now removed the pinch wheel and everything sounds fine. I have found a replacement on eBay for the ridiculous price of 33 GBP. Any advice for a cheaper replacement? I will look into fixing the light!

      Best regards,

      Comment


      • #93
        The outer size of the pinch roller is not that important and I have seen pinch rollers from tape recorders being used successfully. The diameter of the inside bearing of the roller would of course have to be the same as that of the spindle on the Echolette.
        If your tapes are home made they may be contributing the excess noise, I stopped making my own tapes after I compared them to the superior tapes I could buy on eBay for only a few dollars.
        As a side I have just received a later NG51S ( the printed circuit board model) for an overhaul. It has had previous repairs done but appears to be in reasonable condition for it's age. May post on progress with this overhaul.
        Cheers, Mickey

        Comment


        • #94
          Originally posted by oc disorder View Post
          Hi Notea

          I've attached some diagrams which may be helpful.

          The voltages you measured are for record head 3 & 2. You only need to measure where the head connects to the variable capacitor.

          For head 3 you measured 45 volts .. (according to Kazooman) this should be 120 volts AC @ aprox 60kHZ.

          For head 2 you measured 30 volts this should be 90 volts AC @ aprox 60kHZ.

          I suspect head 1 ('s) reading (which is hard to get to under the rectifier) would be lower 10 or 15 volts so
          I guess the oscillator is low on the output.

          The connection from the oscillator coil to the lower center lug of the trim caps is on that bakelite (almost) square tagstrip
          mounted on the coil almost just behind the 12AT7/ECC82 .
          Facing the front of the unit with the transport face down for me it's the top left terminal as per my picture .

          There should be aprox 270 volts AC here at about 60kHZ. I'ts important to use a good multimeter here that won't load down
          the supply which is probably why Kazooman mentioned using an oscilloscope if possible.

          You need to make sure the 270 v AC supply is there before tweaking the trim caps.

          There is a clue on the E51 schematic at pins 3 & 8 of the ECC82/12AT7 - the cathodes.
          11 volts DC should be across R79 , that 470ohm cathode resistor (on S NG 51 it's 500 ohm R37).

          In other words between Pin 8 or 3 and ground if the oscillator is working ok there should be 11 volts.

          Likewise the main power supply should be supplying 290v DC to both anodes of ECC82/12AT7 , pins 1 & 6.

          Hello

          Sorry, but ECC82 is not 12AT7, but 12AU7....

          Comment


          • #95
            Yes You are 100% right. By the time I realised my silly mistake it was too late to edit and correct.

            I MUST remember
            12AX7 = ECC83
            12AU7 = ECC82
            12AT7 = ECC81


            I MUST remember
            12AX7 = ECC83
            12AU7 = ECC82
            12AT7 = ECC81


            I MUST remember
            12AX7 = ECC83
            12AU7 = ECC82
            12AT7 = ECC81


            Hopefully I wont do it again.

            Comment


            • #96
              Hello

              You indicate Bias voltage on record heads, (60v for head one, 90v for head two, 120 volts for head three) on an Echolette NG 51-S.)

              Please, how mesuring these voltages. I own only a METRIX 462 E, and, with HF voltage, i find about 1000volts.

              Thanks for your answer and thanks, too, for ECC82=12AU7....


              Comment


              • #97
                Hello Mecaso

                I think your Metrix 462 E is not able to measure high frequency A.C. voltages.

                You should be able to measure the bias voltage at the coil aprox. 270v ~ 300v AC .

                Most of the info is already here how to connect to measure.. I would just be repeating myself.

                Attaching this picture again .. I can't really improve on this.
                Attached Files

                Comment


                • #98
                  Hello

                  Thanks to Oc Disorder.

                  But, my question was not correctly written.

                  I wanted to say: " With what to make the measures? "

                  (And I had understood well in which place it was necessary to make them.

                  This is the problem of my aprroximate english...)

                  Comment


                  • #99
                    A good quality multimeter ... if you could borrow one from a friend ?.. I don't know brand names for you .. there are some good ones not as expensive
                    as a Fluke but you had better get local advice on a good one.
                    Anyone reading this who can suggest a good reasonably priced meter in Europe that will measure high frequency AC please post suggestions.

                    Comment


                    • Thanks again, Oc Disorder....

                      I have an other problem.

                      On ECC83/12AX7 n°4, DC voltage seems to much low.

                      A2 Voltage is, on my NG51S about 210vDC, but, on the side of R58 (47k ohms) connected on ECC83 n°4,

                      i have only 130vDC. This voltage, when i put the motor "ON", for echos function, starts about 170v DC,

                      and after, a half hour of working, it stabilizes on 130v DC.

                      Of course, echo level is lower after a half hour of working than it is just after starting.

                      I verified all the components connected to this ECC83, I revealed nothing of abnormal.

                      It would be a component, that with the rise in temperature

                      changes of value??????

                      I also replaced the tube ECC83 without more success.

                      I don't know where is the problem! Perhaps do you have an idea....???

                      Thanks again...

                      Last edited by Mecaso; 01-27-2016, 09:48 PM.

                      Comment


                      • Hello again

                        Some ideas...

                        R58 (47k ohms) could be going high under stress/load. (ohms increasing ..going up ) ???
                        C30 (10uF) capacitor faulty ?? "It would be a component, that with the rise in temperature"
                        R61 (2k) faulty ??

                        Possibly only change value (go kaput / go faulty) when conducting. When you measure when off (no power) seems OK.


                        The E51 and the 51S are slightly different in this area.

                        Some voltage readings on E51 may be useful.

                        The valve/tube pins on the 51S may be different .. as "two triodes" are in the one glass envelope.

                        ie P6 = P1 , P7 = P2 , P8 = P3 Mentioning this as can get confusing , designers can use whichever half they like in circuit.

                        Hope that is some help..
                        Attached Files

                        Comment


                        • Originally posted by oc disorder View Post
                          Hello again

                          Some ideas...

                          R58 (47k ohms) could be going high under stress/load. (ohms increasing ..going up ) ???
                          C30 (10uF) capacitor faulty ?? "It would be a component, that with the rise in temperature"
                          R61 (2k) faulty ??

                          Possibly only change value (go kaput / go faulty) when conducting. When you measure when off (no power) seems OK.


                          The E51 and the 51S are slightly different in this area.

                          Some voltage readings on E51 may be useful.

                          The valve/tube pins on the 51S may be different .. as "two triodes" are in the one glass envelope.

                          ie P6 = P1 , P7 = P2 , P8 = P3 Mentioning this as can get confusing , designers can use whichever half they like in circuit.

                          Hope that is some help..
                          Thanks again, Oc Disorder!

                          R58, 47K: i have changed it.

                          C30: i'll change it, but, on "Off" mode, seems OK.

                          R61: i have changed it.

                          Voltages on E-51 are higher. And, on E-51, R61 is different (330ohms instead of 2,2k).

                          I 'll try to be inspired by tensions and differences of E-51 for

                          apply them to my NG-51S.


                          Thanks again...

                          Comment


                          • EUREKA!

                            I think i have found the reason of the problem.

                            It was C28 which varied with temperature.

                            Click image for larger version

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                            I have changed it, and, now, when starting echo function, voltage on the

                            point with R58 & ECC83 plate is about 195v DC.

                            And, after one hour, it is again about 195v DC.

                            For finding the reason of the problem, i had idea to blow hot air with an

                            hair dryer on C28, and, then, i have seen voltage falling down.

                            Sorry, i did not had this idea yersterday....

                            Thanks again for your help...
                            Attached Files

                            Comment


                            • Hello

                              As seen above, I managed to rehabilitate a Echolette NG- 51S I bought

                              on ebay for cheap.

                              Now , for fun, I 'm trying to rehabilitate the one I used in my orchestra in

                              the 70s.

                              On this NG51S, i meet the following problem. the signal recorded by the

                              head #3 is erased by the heads 1# & #2.

                              When in "echo" function , if I take away the tape from heads 1# & # 2,

                              the signal recorded by the head #3 is correctly read by the heads #5 and

                              #4.

                              I had replaced the heads #2 and #3, but the problem persists.

                              I tried to adjust to different values ​​capacitor for

                              premagnetizing heads #1,#2 and #3, but it changes nothing .

                              As soon as the magnetic tape is in contact with the head #2,

                              the signal of the head #3 is completly deleted.

                              This problem is much less sensitive with the head #1,

                              but, it erases a few the signal recorded by the head #3.

                              I should mention that the heads #1, #2 & #3 are recording correctly .

                              I must also say that I demagnetized heads #1 to #5 .

                              I confess , I don't know what to do to try to fix the problem.

                              That is why I called for help on this forum.

                              Sorry to request you again , and thank you in advance for your ideas....
                              Last edited by Mecaso; 02-06-2016, 05:51 PM.

                              Comment


                              • Can anyone measure the double capacitors in the power supply? It seems that I have such capacitors (NOS) and being frankly I don't need them. I'd be happy to give them to guys who restore Echolettes - they are doing good job.

                                Comment

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