Announcement

Collapse
No announcement yet.

Gretsch Fury Reverb issue

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #31
    Originally posted by dc74 View Post
    There is 14vdc flowing off Pin 7 (of the 6973) into the cathode bypass cap, 13.58vdc flowing out of the cap and into the 330ohm resistor...then no voltage on the other side of the resistor...and and therefore no voltage after that to the secondary lead of the driver transformer...
    You have this wrong, cathode cap and the cathode resistor are in parallel, so nothing flows into one from the other. The cathode cap and resistor connects the cathode of the tube to ground, so there will not be a voltage reading on the ground side unless there is a broken connection. The 14 vdc is probably correct in this circuit.

    Did you try a speaker connected to the output of the driver transformer as was earlier suggested? Have you read the resistance of the two sides of the transformer?

    Comment


    • #32
      I did try the speaker trick, and did have good loud signal...but no reverb effect

      If I am testing it correctly, red lead to blue lead & black lead to green lead:
      .250k Ohms on the primary
      0 Ohms on the secondary

      Comment


      • #33
        Originally posted by dc74 View Post
        I did try the speaker trick, and did have good loud signal...but no reverb effect

        If I am testing it correctly, red lead to blue lead & black lead to green lead:
        .250k Ohms on the primary
        0 Ohms on the secondary
        What reverb tank is in the amp? According to the posted schematic, the tank needs to have both input and output jacks grounded. Or the drive cable must be grounded at the circuit end.

        And have you read the resistance of the two tank transducer coils?

        Comment


        • #34
          I'd bet my bottom dollar it is the original stock tank, looks like a Gibbs or a Hammond, with 6647 stamped on top.
          I can crash the tank, so I'm thinking it is in fairly decent order. Also, when I get a signal pop testing caps etc., I can hear the reverb on it.
          I also get a pop when I plug in the output line when the amp is live.

          The Line to the output of the tank (P2, on the schematic) is grounded at the circuit board end; however the schematic does not show the input lead (P3) as grounded just a bare end, no connection, which is how it is wired physically.

          Comment


          • #35
            What kind of voltage should I have at the reverb intensity knob? I'm showing almost nothing...between 1-4 mV

            I tested the .001uF cap, there is 108VDC coming from Pin 1 of V5 to the cap and then basically nothing after that. I actually get a negative reading on my multi-meter, which I don't know how to interpret.
            The start of the lead that runs to the pot shows the same at the terminal on the back of the pot.

            When I test the cap live, I get echo (reverb) on the pop.

            Comment


            • #36
              Seems you are getting reverb'd pops, so the tank and recovery are working.
              Doesn't seem that enough signal is getting to the driver, even though the reverb transformer will drive a speaker. So maybe not enough getting there although some is.
              Or maybe something is miswired and the reverb signal is getting swamped by the (too much) dry.
              Originally posted by Enzo
              I have a sign in my shop that says, "Never think up reasons not to check something."


              Comment


              • #37
                Fixed!

                .001uF cap to the on/off Reverb Pot was bad...replaced it and I'm in chiming shimmery Gretschy/Valco heaven

                Thank you all for putting up with my lack of knowledge and helping me fix my first amp ever!
                She is mostly original, but a previous owner changed the baffle board to a 3x10 instead of a 2x12. So I have 2 SICA SLD 10/80s in parallel on the reverb side, and a single vintage Jensen p10R on the normal channel.
                Cheers - Dc

                Click image for larger version

Name:	Fury.jpg
Views:	1
Size:	3.71 MB
ID:	853115
                Last edited by dc74; 02-18-2019, 10:14 PM.

                Comment

                Working...
                X