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5e3 help

Discussion in 'Amp Tech Center' started by Achysklic, Oct 18, 2020.

  1. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    The three pins together are pins 1,2,8.
    Place your probes on the outside two of those three pins.
     
  2. Achysklic

    Achysklic Tele-Afflicted

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    Good all green lights on pin 2 and 8
     
  3. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    Looking like maybe a bad tube.
    You have 5VAC heater voltage from the PT. The heater filament seems to be intact in the tube yet the tube does not rectify the AC voltage to DC voltage.
     
  4. Achysklic

    Achysklic Tele-Afflicted

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    I order a new tube . Would the tube be bad even if the test good all green on conduct?
     
  5. Achysklic

    Achysklic Tele-Afflicted

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    Ok not wanting another JJ tube after this wants a good rec tube to get
     
  6. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    The tube is essentially two diodes. It needs the 5VAC heater to function. It appears the heater is intact and provided with voltage. It is not rectifying though.

    I would find a 5y3 on ebay. either NOS or used. If you do not want to go that route I would probably buy another JJ unless a tube vender has a vintage tube at low enough cost.
     
  7. Achysklic

    Achysklic Tele-Afflicted

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    Thanks for the help I appreciate it I’ll go on eBay and search for a NOS tube
     
  8. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    I usually get the used ones at a much lower cost. Pretty much they work or they don't. They have a very long lifespan.
     
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  9. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    In the meantime...
    I would suggest a couple of things to protect the rectifier and to help insure a quiet amp.

    InkedAchysklic5e3_LI.jpg

    I would disconnect the HT and heater center taps and connect them as illustrated.

    The HT CT (red/yellow stripe) creates less buzz when attached to the first filter cap negative terminal. (I have it shown connecting to the bias resistor/cap. If the wire is long enough try to get it to the filter cap.)

    The heater CT makes for quieter hum when it is elevated. It is easy to elevate on a (5E3) cathode biased amp because of the approximately 20V bias voltage. (Elevated just means instead of using the 0 volt ground it is *grounded/elevated* to a higher voltage.) Simply connect the green/yellow CT to the junction of 6V6 pin8 and the bias resistor/cap.

    The bias resistor (orange arrow) gets very hot. Move it toward the edge of the board so it will not heat the bias capacitor.

    The red arrows pointing to the rectifier socket. Have a look at Rob Robinette's 5E3 mods site. There is a section - Rectifier 'Backup' Diodes. These diodes will help protect the rectifier tube. The tube doesn't have to work as hard = longer lasting tube.

    Also in the 5E3 mods site there is *how to build a light bulb limiter*.;)
     
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  10. D'tar

    D'tar Friend of Leo's

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  11. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    Good job *Eagle Eye* @D'tar .

    I didn't catch those resistors in the wrong positions. That'll save some troubleshooting down the line!
     
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  12. Achysklic

    Achysklic Tele-Afflicted

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    I ordered new diodes and rec tube. This morning I wanted to get it one more shot I put the rec tube back in and turned it on this time the rec started to glow cherry red and got very hot I hurried up and turned it off.
     
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  13. Achysklic

    Achysklic Tele-Afflicted

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    No idea what would have caused that!
    It’s like that tube ran away.
     
  14. D'tar

    D'tar Friend of Leo's

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    Man made....

    JJ5y3s are pretty robust and not too far off voltage drop like some others. You just got a dud. I wouldnt hesitate to get another. NOS or anos 5y3gt will serve you well and they are not super $$$.
     
  15. EmWeAh

    EmWeAh Tele-Meister

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    it's hard to see on the pics ... but is V1 p3 bridged to v1 p8?
     
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  16. Achysklic

    Achysklic Tele-Afflicted

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    No it isnt,
    But it is now...thank you I never notice the bridge on my diagram till you mentioned it.
     
    Last edited: Oct 19, 2020
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  17. Achysklic

    Achysklic Tele-Afflicted

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    I took the Rec tube back out it’s definitely blown now you can hear it rattle when you shake it.
     
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  18. Achysklic

    Achysklic Tele-Afflicted

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    Got a question, going back over wiring double checking. My OT is a classic tone 40-18022. On one side a blue, black , red wire on the other side a green and yellow wire all the diagrams I can find don’t show this color code is the black wire the same as the brown on robs diagram? And the yellow the same as the black?
    With black going to v4 pin 3 and blue to v3 pin 3.
    And green going to six jack and yellow to speaker jack?
     
    Last edited: Oct 21, 2020
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  19. D'tar

    D'tar Friend of Leo's

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    upload_2020-10-21_10-23-43.png

    OT primary,

    Green to 6v6 plate

    Red center tap to B+

    Yellow to 6v6 plate

    OT secondary,

    Black to output jack ground

    Blue to output jack tip
     

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  20. Uncle Daddy

    Uncle Daddy Tele-Afflicted

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    I had that happen once when I didn't have the tang on the tube spigot in the slot on the socket base. I'd got the tube in wrong as it was a sloppy fit.
     
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