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    Krank schematics

    https://guitar-gear.ru/forum/topic/1491-krank-krankenstein/

    https://el34world.com/Forum/index.php?topic=15354.0

    https://www.diyaudio.com/forums/instruments-and-amps/85870-krank-circuits.html
    ...
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    Before testing, soldering elco contacts or clean...

    Before testing, soldering elco contacts or clean from the oxide.
    When testing cathode elco unsolder cathode resistor from elco
  3. For the 6550, the cathode and screen g3 are...

    For the 6550, the cathode and screen g3 are connected in the tube itself and executed at pin 8.
    To adjust the quiet current connect a 1 Ohm resistor from pin 8 to the chassics.
    Pin 1 is neutral (N...
  4. Pin 8 is cathode and must be grounded. Screen g3...

    Pin 8 is cathode and must be grounded.
    Screen g3 in some tubes is connected to the cathode in the tube itself, or as EL34 derived as a separate electrode that must be grounded.
    Look at layouts...
  5. Basically at octal power tubes except 7027 and...

    Basically at octal power tubes except 7027 and EL34 pin 1 is no connected and is used for various purposes.
    At EL34 pin 1 (screen g3) must be connected with pin 8 (cathode)
    7027 has a different pin...
  6. When measurement the cathode current, in addition...

    When measurement the cathode current, in addition the anode current, screen current g2 also enters.
    Measuring by the OT resistance is perhaps the more reliable variant since only the anode current...
  7. Quiet current or calm current or idle current is...

    Quiet current or calm current or idle current is defined by bias voltage.
    One tube don't damage OT.
    When adjusting the bias, the loudspeaker must be connected to the amplifier.
  8. When you set the quiet current with one tube, you...

    When you set the quiet current with one tube, you can normally put another tube.
    It goes without saying that the tubes are relatively matched.
    With only one tube in the socket you can measure and...
  9. To start, put one tube 6550 in socket. ...

    To start, put one tube 6550 in socket.
    Previously with the bias trim pot set to the highest -Ug1 value (- 55 V min), put one 6550 and gradually decrease the -Ug1 to set the quiet current to the...
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    The voltages on V2 and V4 are fine.

    The voltages on V2 and V4 are fine.
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    If volume and tone controls not work at anode V2...

    If volume and tone controls not work at anode V2 (pin 6) check capacitor connection .1uF; .022 uF and 250 pF with tone control pots.
    Check the anode and cathode voltages on tube socket V2.
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    https://www.scribd.com/document/369047600/MXR-117-...

    https://www.scribd.com/document/369047600/MXR-117-Flanger-Service-Schematic

    https://drive.google.com/file/d/1vpHJanRoGtZgz-OA0p3wA4mDucRT0-ca
    ...
  13. The value of the bias voltage depends solely on...

    The value of the bias voltage depends solely on the bias voltage divider (15 kOhm) according to (56 kOhm + 22 kOhm bias trim pot)
    Bias feed resistors (100 - 220 kOhm) and grid leaks resistors (1.5...
  14. About biasing tube guitar amplifiers

    https://music-electronics-forum.com/showthread.php?t=8291

    Bias adjusts depending on the + HV and working classes of service (A, AB, B) to the specified anode current value.
    ...
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    Since sound sensations do not exist when the head...

    Since sound sensations do not exist when the head is separated from the cab, the cause should be sought in the head.
    In the background when you're not playing there is a modulated sound like a...
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    With a gentle knock with finger on the output...

    With a gentle knock with finger on the output tubes check if there are any audible sensations.
    If the output tubes worked for a long time, the electrodes in them move slightly (usually in rhythm of...
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    https://music-electronics-forum.com/attachment.php...

    https://music-electronics-forum.com/attachment.php?attachmentid=55537&d=1570868287

    If you followed the story neatly you would notice that (red point X) referred to Normal ch.

    We will repeat the...
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    Have time for schemarics, voltages, scope...

    Have time for schemarics, voltages, scope pictures ...
    First needs to be started Vibrato ch step by step.
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    About Fender signal test voltages

    55559
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    Vibrato ch check step by step Put in socket...

    Vibrato ch check step by step
    Put in socket second and fourth tube (12AX7)
    Set Vibrato ch controls / Volume 5 - 7 / Bass 4 - 5 / Treble 5 - 8 / Reverb 0 / Bright sw OFF

    Plug guitar into Vibrato...
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    Do you now have a powerful and clean sound when...

    Do you now have a powerful and clean sound when you plug and play guitar into Normal ch or Vibrato ch inputs?
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    I don't understand why a persistent error when...

    I don't understand why a persistent error when voltage measurement on a dummy load (level voltages are in the mV )
    For 50W at 2 Ohm the voltage on the dummy load (speaker) is 10VAC

    So I insisted...
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    Every test equipment was work OK, but ... ...

    Every test equipment was work OK, but ...

    repairman is trying.
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    If these oscillograms are a signal source via...

    If these oscillograms are a signal source via .001uF to power amp they are fine.

    Since you say that you did some mod on FSR, it would be best to compare the factory layout from schematic with your...
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    I doubt. Wall wart transformers give mostly DC...

    I doubt. Wall wart transformers give mostly DC voltage.
    You talked about the standard lab type bench power supply. “Wall wart” is not a lab type bench power supply.

    What does it say on “wall...
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    The standard lab type bench power supply provides...

    The standard lab type bench power supply provides DC voltage and cannot be used to test transformers.
    Only the AC voltage source can be used to check the transformer.
    If you use variac, variac...
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    That you can hear the guitar pretty quiet, it can...

    That you can hear the guitar pretty quiet, it can be pre-listening normal ch through vibrato ch through common cathode connection (point A) if you set tubes also for vibrato ch.

    Your photo does...
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    For P7... only ...

    For P7... only

    https://www.technicalaudio.com/pdf/Gordon_Clark_folder/Magnecord_Magnecorder_PT7-P_Instructions.pdf

    https://www.technicalaudio.com/pdf/Gordon_Clark_folder/

    Can you post a...
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