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Low Volume 5F1...

Discussion in 'Amp Tech Center' started by James Knox, Oct 31, 2020.

  1. James Knox

    James Knox Tele-Holic Silver Supporter

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    Phoenix
    ...in fact, almost no signal. Very faint.

    I pulled out my very first build, a Mojo Kit. It always sounded good, but noisy. I decided to replace all the Carbon Comp Resistors that came with the kit with Carbon Film. After I replaced them, have almost NO volume. I figured it had to be in the work I just finished.

    I checked every R value. I reflowed every connection. I checked continuity. Checked every voltage. I tried different tubes, cables, speakers. Here are some pics and my voltages. Can you spot something amiss for me? Thanks in advance for your help!

    Wall 118vac - B1 381 - B2 337 - B3 282

    V1 12AY7
    1- 299
    2- 0
    3- 2.25
    4- 3.2
    5- 3.2
    6- 192
    7- .006
    8- 1.5
    9- 3.30

    V2 6V6
    1- 363
    2- 3.4
    3- 393
    4- 360
    5- .005
    6- .003
    7- 3.4
    8- 23.1

    D52C185C-81A5-46A2-9202-C6A0F358C15F.jpeg 5960115D-DA69-4A47-B9B3-A639EBA55B8D.jpeg B070AAD0-19BA-4F91-A9E0-0E76CC7FA41F.jpeg 1AD2BF90-D789-4B61-A2A7-B8A111234FB3.jpeg 7805EA8C-F64D-489C-8955-50F980712260.jpeg 2EDAC6C7-02E6-4D1A-A2CE-EADD9F2F7A9E.jpeg
     
  2. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    You have a 100R plate resistor for V1 pin1.
     
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  3. elpico

    elpico Tele-Afflicted

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    You've got 100ohm resistor on first stage plate instead of 100Kohm.
     
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  4. D'tar

    D'tar Friend of Leo's

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    That will shush things a bit!;)
     
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  5. James Knox

    James Knox Tele-Holic Silver Supporter

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    OMG, what a “rook”. I fell for the old 100K vs 100R mistake!

    I looked at that at least 5 times.

    Thank you so much Brother!
     
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  6. rjtwangs

    rjtwangs Tele-Afflicted Silver Supporter

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    It absolutely amazes me consistently that some of you guys are able to spot mistakes from photos. There is a real treasure trove of knowledge here. Well done everyone!!!!


    RJ
     
    Last edited: Oct 31, 2020
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  7. James Knox

    James Knox Tele-Holic Silver Supporter

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    Amen - the Shock Brothers are the Best Brothers a Guy could have!
     
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