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Deluxe reverb build bad hum

Discussion in 'Amp Tech Center' started by Achysklic, Mar 5, 2021.

  1. Achysklic

    Achysklic Tele-Afflicted

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    Here is my DR build at idle is with nothing plugged Into it has a bad hum. I checked all the connections and installed a ground bus and tried different tubes nothing helped. The reverb isn’t working as well. Here’s a video of it. Thanks
     
  2. Jon Snell

    Jon Snell Tele-Holic

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    What is the layout like ... can you post some pictures?
    The hum increase when ypu get close to the top of the amplifier I would say is open circuit inputs or a badly wired grid connection.
    I will have a better idea once I can view the internals.
     
  3. Achysklic

    Achysklic Tele-Afflicted

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    B615CE77-793F-4A15-803C-E7D25830CCD4.jpeg CF3AD73D-C4CE-49E9-BC19-879D4FCAC25F.jpeg E3366403-2674-4E7D-9514-150ABE24CACE.jpeg 46B0FF40-228C-4A9F-B9EA-D0181437481D.jpeg 07B3A72C-B168-4502-9B3E-98E9B727C61C.jpeg D876CBC2-F66A-422B-9BA2-FF8C2D11FC25.jpeg 8A7CB544-396B-4C3D-A6C0-BC75423260C1.jpeg BFD51569-4BB1-4CAE-A14D-BADE4813944B.jpeg 49D3848A-70B2-4345-B059-62117F8DF886.jpeg BD9A0B54-6951-4F24-9D6F-05576639B125.jpeg
     
  4. Achysklic

    Achysklic Tele-Afflicted

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    EF93F978-4360-4C57-A36C-EFD44A7F669D.jpeg 864A0528-98EF-41EF-9BCA-D37697839652.jpeg 864A0528-98EF-41EF-9BCA-D37697839652.jpeg 139EF70E-EBDD-4760-8851-C92D7F913F56.jpeg
     
  5. Jon Snell

    Jon Snell Tele-Holic

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    Looks like there is no ground switch connection on this input jack ... Screenshot 2021-03-05 at 19.47.52.png or is there ... Screenshot 2021-03-05 at 19.49.02.png
    Grid leak resistors? I can't see them on the first stage at all.
     
  6. Achysklic

    Achysklic Tele-Afflicted

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    I did a continuity test on all the leads and the ground bus all checked ok. I also double checked ever resistors value to make sure they were in the right places.
     
  7. Achysklic

    Achysklic Tele-Afflicted

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    There is a ground the black wire going to the one jack and two 68k resistors connected to both jacks
     
  8. Achysklic

    Achysklic Tele-Afflicted

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    This pic may show it better it was taken before I installed the ground bus. CC855CD8-F69A-44D8-B4BB-CC0F15678C0E.jpeg
     
  9. Jon Snell

    Jon Snell Tele-Holic

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    Screenshot 2021-03-05 at 20.15.05.png
     
  10. Achysklic

    Achysklic Tele-Afflicted

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    This is how I wired it. DE771676-FC0F-46A9-ACD6-4C00D29FF7F1.jpeg ABC0B1B5-E69C-42B4-9156-A2C536EDE2EA.jpeg
     
  11. goldguitarguy

    goldguitarguy Tele-Meister

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    It’s definitely a ground issue... That’s a lot of AC hum. Verify your filter capacitors are connected correctly. Then verify your input and output jacks are isolated from ground when the ground shunts are open.

    Also is this an unconnected wire poking it’s head out here? 24D3A8FA-1D95-4A25-96C7-E9478C2A35BE.jpeg
     
  12. goldguitarguy

    goldguitarguy Tele-Meister

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    Also where is the ground from your dog house going to?
     
  13. schmee

    schmee Doctor of Teleocity

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    A couple things, may not be related to all that much buzz though:
    -Get rid of that big copper ground buss. Ground all the preamp stuff right near the jacks. Ground the power transformer and that stuff at the transformer or nearby.
    -Check that the green wires to the pilot light are not grounding on the light somewhere. This is easy to do with solder that has run down etc.
    -I assume the wire under the diode board is there that goes from the diode to the cap? Dont see it sticking out of the solder glob.
    -With that constant buzz I wonder if all the wiring is correct to/under the cap can?
    -Make sure the ground from the cap doghouse is near the PT.
     
  14. Achysklic

    Achysklic Tele-Afflicted

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    Ok that wire is not connected.
     
  15. Achysklic

    Achysklic Tele-Afflicted

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    I’ll get rid of the ground bus and see if it helps. I was under the impression it was best to have one
     
  16. Achysklic

    Achysklic Tele-Afflicted

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    Yes the wire is connected to the food on the board. I’ll triple check the wiring under the cap can.
     
  17. DADGAD

    DADGAD Friend of Leo's

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    On the output tubes, make sure pin 2 is wired to pin 2 and pin 7 to pin 7 of the second one. If those are swapped, you get hum. Also, increase the 25uf negative bias supply capacitor to 100uf.

    Good luck!
     
  18. 2L man

    2L man Tele-Meister

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    Ground bus is connected to chassis two places so technically it forms a ground loop! Only very close the input jack is enough and then no operative current runs thru chassis! Steel input jack without insulation should be fine way to connect groung bus to chassis because there does not run any current thru it.

    Only one other wire needs to be connected to chassis and it is mains cable earth!

    All other parts of circuit should be insulated from chassis. If two to four steel input jacks are used perhaps they do not need insulation but for loudspeaker I recommend insulated.

    Othervise that is most solid ground bus I have seen so far!!!
     
    Last edited: Mar 5, 2021
  19. Achysklic

    Achysklic Tele-Afflicted

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  20. Achysklic

    Achysklic Tele-Afflicted

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    Thanks everyone I’m going to try all the suggestions and see what happens
     
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