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Blues junior III tube socket

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  • #16
    Sorry for jumping in so late to your thread. Can you tell me what the original complaint/symptom was from the customer on this Blues Junior?

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    • #17
      Originally posted by mikeskory View Post
      Sorry for jumping in so late to your thread. Can you tell me what the original complaint/symptom was from the customer on this Blues Junior?
      They were playing a club , amp was good for sets 1&2 , set 3 no sound , power light on, no fuse blow , just no sound . Amp was repaired before when the owner installed new PT's and broke every solder connection on V4 & V5 , improper re flow(guilty) lasted 10 months. Amp just went out Friday, they had a wedding gig Saturday . Phone hasn't rang , so hopefully all is good.
      Last edited by shortcircuit; 08-06-2019, 08:16 PM.
      If you don't know where your going any road'll take you there : George Harrison

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      • #18
        The reason I ask is I have one on my bench now. It makes a loud crackling-gurgly noise...sometimes. I worked on it last year, another guy worked on it 6 months ago and now I've got it again. So far: New tube sockets, replaced 3 of the ribbon cable with wire, new r3000 diodes, new output trans and more. Noise still there and it looks terrible. Embarrassing. So after reading this post I ordered the new board and new ribbon cables.

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        • #19
          Just have to ask , have you replaced the jacks ?? Double check all your pot connections as well if you can, all vulnerable culprits. Did you order one of nickb's boards ??
          If you don't know where your going any road'll take you there : George Harrison

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          • #20
            Originally posted by mikeskory View Post
            The reason I ask is I have one on my bench now. It makes a loud crackling-gurgly noise...sometimes. I worked on it last year, another guy worked on it 6 months ago and now I've got it again. So far: New tube sockets, replaced 3 of the ribbon cable with wire, new r3000 diodes, new output trans and more. Noise still there and it looks terrible. Embarrassing. So after reading this post I ordered the new board and new ribbon cables.

            Does removing the PI tube make any difference? If no, have you tried removing the EL84's one at a time and then both? If it still happens with both, disconnect the output transformer one terminal at a time, first the plates then the center tap. Remember safe practice, the discharge the B+ and pull the power plug from the wall
            Experience is something you get, just after you really needed it.

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            • #21
              Sorry. Gigs this week have me buried. @shortcircuit: In answer to your question, yes I ordered Nicks board. It was like $38 w shipping plus ribbon cables fro Darren's website. It makes sense but also I started thinking about you guys looking at my work. LOL! @NickB With both EL34s out there is no noise as I can tell with the scope. When both tubes are in I can see the noise on the speaker leads and a smaller version going in. Note: I put in a new OT, noise the same. The noise is loud and at full volume...controls don't change it. But I'll try one at a time and see if I can isolate the cause. 2 more gigs. I'll be back to work Monday and will fill you in. Thank you.

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              • #22
                Originally posted by mikeskory View Post
                Sorry. Gigs this week have me buried. @shortcircuit: In answer to your question, yes I ordered Nicks board. It was like $38 w shipping plus ribbon cables fro Darren's website. It makes sense but also I started thinking about you guys looking at my work. LOL! @NickB With both EL34s out there is no noise as I can tell with the scope. When both tubes are in I can see the noise on the speaker leads and a smaller version going in. Note: I put in a new OT, noise the same. The noise is loud and at full volume...controls don't change it. But I'll try one at a time and see if I can isolate the cause. 2 more gigs. I'll be back to work Monday and will fill you in. Thank you.
                When you get back put the EL84's back in and pull the 12AX7 next to the EL84s and report on the noise status.
                Experience is something you get, just after you really needed it.

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                • #23
                  Originally posted by mikeskory View Post
                  I started thinking about you guys looking at my work.
                  can we get before and after pics
                  If you don't know where your going any road'll take you there : George Harrison

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                  • #24
                    I got the new output board. It fit perfect. looks great and also replaced input jack and the ribbon cables for V1, V2,V3. Still noisy. A whooooshing sound. I gotta forget everything I've done and start troubleshooting all over...like its a fresh job. I also pulled the EL84s individually. Same whooshing sound either way. BUT...IT LOOKS GOOD! Talk tomorrow.

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                    • #25
                      @Shortcircuit No! Lol!

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                      • #26
                        Originally posted by mikeskory View Post
                        It makes a loud crackling-gurgly noise...sometimes.
                        Still noisy. A whooooshing sound
                        Is the noise consistent or intermittent ??? Did you also pull the phase inverter tube as nickb suggested ??
                        When you get back put the EL84's back in and pull the 12AX7 next to the EL84s and report on the noise status.
                        If you don't know where your going any road'll take you there : George Harrison

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                        • #27
                          Yes I pulled phase inverter. It got quiet for about 5 seconds then started the ...shshSHSHSHshsh...again. I've had it on now for about 30 mins. After about 10 mins the noises get louder and more of a sharp crackling. NOW If I pull the phase inverter, the sounds are not as loud but the same intensity. I also put in a fresh set of tubes just to eliminate that. ALSO, this may be completely unrelated but I've just noticed the reverb does not work. I asked the customer (he works here at the store) if that had been an issue. He said a few years ago he replaced the reverb tank with a used one). The signal lead was unsoldered so I'm replacing the aftermarket RCA on the "out" cable plus cutting it back an inch. I'll let you know....
                          Last edited by mikeskory; 08-13-2019, 03:57 PM.

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                          • #28
                            We now know
                            1) It's before the EL84's
                            2) It's after the LTPI
                            3) It's common to both EL84's
                            The common things in that area are the bias supply and the HT supply to the LTPI. Of course there is an outside chance that you have two faults but will cross that bridge if we come to it.

                            So let's look a the HT supply first. There are a few ways you can do this. Super easy is just to cut one leg of the 10K filter resistor R48. This will kill the HT supply to everything after and including the LTPI. Remember to discharge the power supply. If that fixes the noise then the 22uf cap C27 is the prime suspect. Just solder another one in parallel and carefully solder the resistor wire you cut to bridge the cut and reinstate the connection.
                            Experience is something you get, just after you really needed it.

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                            • #29
                              Just a note , I replaced C34 on the BJ3 I had
                              Last edited by shortcircuit; 08-14-2019, 12:54 AM.
                              If you don't know where your going any road'll take you there : George Harrison

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                              • #30
                                Bringing you up to date. The reverb had a 3rd problem. The OUT jack was intermittent so I re-soldered the thin wires inside the tank. Once the reverb was working, the noise settled down. For 2 days I had no noise. This morning it had a quiet shshsh-ing sound. I replaced C32/C33 but still had the quieter shhhh sound. Replaced C31/C34 and still had the same quieter shhhing sound. However, NOW when I pull out the phase shift V3 all the stray noises are gone. Clipped in the 22mf over all 3 caps...same. Now the noise is so quiet I could barely hear it. Something else I notice...the Treble and master pots were very noisy. After spraying them a second time their noise quieted down. Now the amp is quiet as a church mouse. Can pots be so bad they cause a noise? We'll let if cool down and rest till Friday.
                                Last edited by mikeskory; 08-14-2019, 09:56 PM.

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