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Crate BV50-H loud hum on clean channel

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  • Crate BV50-H loud hum on clean channel

    OK..so I got the Crate together after changing filter caps ,and some tone stack components. Tubes in ,power on, no input , I'm getting a very loud hum. So...when it cools I'll take a look at my work. Note: I had to alter the filter cap placement because they were taller , so they are laying over as opposed to standing. I changed a couple of resistor values ,and wattage in the tone circuit ,as well as cap value.
    I switched to the dirty channel ,and it is quiet as a church mouse. Plate voltage is 470 , Tube bias reading is 22.2 ma , tubes are JJ KT66.
    I haven't tried much else yet . I will swap preamp tubes later after work.

    Thanks
    Attached Files

  • #2
    Crate BV50-H updated ,shematics

    After checking solder joints ,and a general lookover ,I powered up again , checked some voltages with the quiet channel on (channel 2), no input , Voltages seem a little high ,more so on V1 than V2. When I switched to channel 1 the hum still there, I poked around nothing made any sound change. When I was reading voltages with this one on ,and touched the socket pins it was really making some noises ,and seems to make the hum louder . I did also check the filament voltage ,and it is low at about 3.2 from ground to TP. Unless that is measured across which actually would be 6.4 . Maybe the resistors I changed could cause this ?

    V1-6 expected 180vdc , actual 205vdc
    V1-1 expected 190vdc , actual 207vdc
    V2-6 expected 140vdc , actual 165vdc
    V2-1 expected 170vdc , actual 185vdc

    Ok..apparently it didn'.t like my component changes, so they have been corrected (mostly), and the hums is gone. Live ,and learn

    Other voltages seem pretty close.
    Attached Files
    Last edited by gtrplayr1976; 04-30-2011, 11:51 PM. Reason: update

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