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Hartung amplifier project

Discussion in 'Audio' started by Ian Mason, Dec 24, 2017.

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  1. Ian Mason

    Ian Mason

    Dec 24, 2017
    Hi Duke, I am in London and if you are serious that you would help me with the amp I am heading that way on the 3rd of January would you mind if I took 1 hour of your time for you to test the transformer and show me the proper method of wiring it up, I would be happy to pay for your time to show my appreciation, please let me know, I would be so grateful but I also understand if you were not serious or that you don't have the time.
    Thanks Ian
  2. duke37


    Jan 9, 2011
    I have had a look at the transformer.
    1.Inner connection marked with a black tag.
    2.Next connection plain white wire.
    3.Next connection marked wth a black tag.
    4.Last connection plain white wire.

    Connecting 2 to 3 and putting mains into the150V winding gives 200V or so on the primary

    Connecting mains to 1 and 4 gives over 250V on the 250V winding. I do not have the measured value here.
    The mains fuse was blown. When this happened is unknown, it was replaced with a 1.5A fuze.
    The rectifiers remain to be connected.

    Ian seemed envious of the scenery here, it is very nice until you get snowed in.

  3. Ian Mason

    Ian Mason

    Dec 24, 2017
    Hi Trevor, once again thanks so much for your help, I was very envious of where you live, I am back home now and have all components joined but unfortunately it failed to work, nothing to do with what you have done I might add, seems that I will now have to find some additional help close to London, as you can imagine I was very disappointed as I seemed to have followed the schematic and double and treble checked all of the work, anyway I will now go off and start a new thread begging for some help.
  4. 73's de Edd

    73's de Edd

    Aug 21, 2015
    Sir Ian Mason . . . . .

    ? ? ? ?

    Did Sir Trevor show you his RED tractor . . . . .or forbid . . . .even let you strip its gears in a test drive ?


    A first step might be to just work with one channel and initially confirm if you have the two supply voltage levels present on the plates of your tubes ?

    And with the unit turned on are you seeing the dull orange glow of your tubes filaments ?
    If so, you must have properly interpreted the proper tube pin numbering scheme around the periphery of the tubes.

    Then you plug in headphones and take an insulated test lead, having clips at either end, and take a 1 meg or greater resistor and connect one insulated clip to the 150VDC supply and the other to one lead of that resistor.

    Holding that test lead by its insulated portion swing the free end of the resistor across the 1st grid of the 6080 .
    ( That's at the junction of the 330K and .47 ufd capacitor. )

    Make the temporary connection action as fast as if you were striking a match.
    If all is well in that stage, a burst of static should come from one phone connection.
    If not, see if you mis wired the phone connector .

    If that 6080 stage popped move on to the first amp stage, with its smaller tube and place the volume control to center position, just in case you wired it backwards.
    Then do the same ultra fast connection to see if the one earphone makes the expected noise.

    Standing By . . . . . and possibly

    COMING UP . . .
    Injecting test audio into the 6SN7 stage using a "Wet Willie" or a sampling of your 6.3 VAC filament voltage.

    73's de Edd . . . . .
  5. Ian Mason

    Ian Mason

    Dec 24, 2017
    Unfortunately the valves are not even glowing, it seems that the power is not getting that far and indeed not even going through the first capacitor, I am starting to doubt my wiring of the bridge rectifier/s
  6. duke37


    Jan 9, 2011
    The glow in the valves comes from the filaments which are fed from the thick 6.3V winding. White/red. Do not confuse with the 110V (red) thin winding.
    The valve filament connections are pins 7 and 8 in both cases. You can check for a connection through the valve before connecting the transformer winding.

    I would disconnect the rectifiers and check the valves for a feint glow, then remove the valves, replace the rectifiers and measure the voltage on the reservoir capacitors. Remember you are dealing with lethat voltages.

    The RED tractor is officially orange and has long gone. Nuffield were taken over by Marshall who used blue and JCB used the skid for a digger. The latest tractor of this series contained bits from all three sources and was called Joseph because of its coat of many colours.

  7. Ian Mason

    Ian Mason

    Dec 24, 2017
    Thank you, I have now stripped it back completely ready for a new build, it was a bit of a mess which would have made diagnosis a nightmare for me, I will now rebuild with tag boards or turret boards with solid core wire to try to neaten the project up a bit, my soldering also left a lot to be desired so I will have a chance to improve that too, I will report back with my progress, thanks for your help.
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