A15Mk2 /trubble schooting??

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    • A15Mk2 /trubble schooting??

      Hello.
      I am Adriaan Jansen From Holland and I have bild my first AMP ever, just for hobby and practish at home.
      Now I fond some difficults with assembling (mostly caps code) but in the end I had everithing used, so I think its all in his place.

      But now by testing its only one big "hum "

      The Rectifier voltage is far to high!! 480V, ad c26+ I have over 485V.
      Primair 230,and secundair 265, 24, 7,4V is OK
      Bias is only 15,9V
      Heater and tube sockets 7,00V.

      I cant find the corse and there is no trubble schooting page (like,IF not do this) jou understand.

      Some body give me a hind if jou please, NB hope jou can read my ENGLISCH?
    • Hi,

      pictures would help. Did you double check the rectifier wiring, and ist the ground connection of the rectifier and the first elko ok? 480V with correct wiring is impossible, sounds like the elko is floating around...

      My advice: Check the grounding of the power supply and post some pictures. Without it's wild guessing.

      Nils
    • Thanks for jour support!!

      Thanks for jour support!!

      Nils;324935 wrote:

      Hi,

      pictures would help. Did you double check the rectifier wiring, and ist the ground connection of the rectifier and the first elko ok? 480V with correct wiring is impossible, sounds like the elko is floating around...

      My advice: Check the grounding of the power supply and post some pictures. Without it's wild guessing.

      Nils


      Im trying to get the pictures send now,
    • Hi Adriaan,

      The Rectifier voltage is far to high!! 480V, ad c26+ I have over 485V.
      Primair 230,and secundair 265, 24, 7,4V is OK
      Bias is only 15,9V
      Heater and tube sockets 7,00V.


      If the xformer AC voltages are in the normal range - especially 265 V ac for HV - it is nearly impossible to get 485 V from it (370 V dc are to be expected).

      How did you measure it?: Kind of DVM (batteries OK?), which voltage range (AC/DC?) where did you connect the black (an red) measuring Strips?

      BTW Heater voltage 7 V? - Did you all the measurements without tubes?
      :confused:

      Groetjes, Bernd
    • images

      I herewith attach some pictures, maybe this will help you to solve the problem?
      Adriaan




      eBernd;324939 wrote:

      Hi Adriaan,



      If the xformer AC voltages are in the normal range - especially 265 V ac for HV - it is nearly impossible to get 485 V from it (370 V dc are to be expected).

      How did you measure it?: Kind of DVM (batteries OK?), which voltage range (AC/DC?) where did you connect the black (an red) measuring Strips?

      BTW Heater voltage 7 V? - Did you all the measurements without tubes?
      :confused:

      Groetjes, Bernd
      Images
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    • Measure roadmap

      Measure roadmap

      Hello,Nils,eBernd:
      First thanks for your support!!.

      I neded some time to send the pictures ,but ok .

      Meaby I did messup the AC/DC understanding, AC wissel/DC gelijk stroom.

      The first measure I did without tubes (on switsh) on the primear/secundair side.
      Than with tubes,8Ohm speaker + the standby switsh.
      All i read is that the heater voltage is 6.1/6.9 V AC.
      My "Kingcraft"multymeter (aldi) is not proff. but OK 9Vbattery( checkt)

      Meaby I need a raodmap for the measuring with the AC/ or DC values.
      NB, because of the (strong) humming I stopt all activitie''s for the moment.
      Images
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    • Hi,

      all voltages except the heater voltages are DC (gelijk).

      A lot of hum means often (but not always) a missing ground connection.

      That would be the first I would search for.

      If your multimeter has a beeper function you can use it for otherwise make the check with the lowest ohm range.

      ATTENTION: The power supply capacitors have to be entirely discharged for this so check this before starting...

      Another cause could be a wrong power supply wiring:
      There has to be no AC Voltage at the capacitors C26, 28, 30 (a few millivolts would be ok). This you have to check in the AC range.

      ATTENTION: you have to be experienced making measurements on high voltages to do this - otherwise leave it!

      Bernd
    • Fehlersuche AMk15 ii

      Fehlersuche AMk15 ii

      eBernd;324970 wrote:

      Hi,

      all voltages except the heater voltages are DC (gelijk).

      A lot of hum means often (but not always) a missing ground connection.

      That would be the first I would search for.

      If your multimeter has a beeper function you can use it for otherwise make the check with the lowest ohm range.

      ATTENTION: The power supply capacitors have to be entirely discharged for this so check this before starting...

      Another cause could be a wrong power supply wiring:

      OK Alle Puzzlleteile fugen sich!.Ein gruner Draht vergessen oder tatsachlich gesagt in einen Tof statt gelotet auf der platine(Oben abgebildet der dritte stift von Erde, und Fahrgerause!.Die multi-Meterrichtig eingesteld(ac/dc) und schauwen sich alle Werte ubereinstimmen,die Heizspannung(35mv) gesetz und siehe da,ein tollen Sound.Auf der Clean -kanal ,der bass Poti groben Einfluss auf die Lautstarke,habe ich vielleicht ein wenig verwirtt??
      Die beide mini schalter sind leiter met solderen kapoet??? oder sowas?
      Ich habe auch den fubschalter Option bestelt ,wenn ich noch broblemenIch weis wo ich kann!! Far bedankt fur Ihre Unter stutzung danken,
      Adriaan Jansen
      Email adriaan51049@casemas.nl

      There has to be no AC Voltage at the capacitors C26, 28, 30 (a few millivolts would be ok). This you have to check in the AC range.

      ATTENTION: you have to be experienced making measurements on high voltages to do this - otherwise leave it!

      Bernd


      NB I checkt the votage on cap c28 after the sjut down of the amp,and it fade out in les then one minnet so its ok to measure after this Ithink