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Old CryBaby wah pedal nnot "wah-ing"

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  • #46
    As the inductor pins the wire is attached to are accessible without removing the board: Inspect them with magnifying lens for a broken wire.
    - Own Opinions Only -

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    • #47
      To remove the treadle, you must break out axle that connects the treadle to the wah chassis.
      Click image for larger version

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      Who does not know and knows that he does not know - teach him Confucius)
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      • #48
        OK - would I just use a hammer and a punch and punch the axle out? Man, that makes me nervous about causing permanent damage! I'm going to look for the broken lead wire, and also try to free the front treadle bolt from the board by heating the bolt first. I'll need some direction if I have to knock out the treadle axle.

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        • #49
          As said earlier, first loosen the lower (battery side) nut before punching the axle out. Otherwise you might break one of the tensioning screws.
          Last edited by Helmholtz; 10-08-2020, 11:57 PM.
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          • #50
            I question the need to dismantle the wah in order to establish the fault. You should be able to measure the DC voltages and intercept the signal path at any point from the component side - sometimes not on the component itself, but at the junction with another one. Those 'tropical fish' caps can go open and can be paralleled with a good cap to check - just hold it in position.

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            • #51
              SUCCESS !!!!! I got the dang circuit card free !!

              I held a hot soldering iron to the protruding bolt bottom while tugging with a pair of mini-pliers, and it came right off after a few seconds. I got a massive does of varnish smoke in the eyes, though, and boy did THAT burn for a couple of seconds...it turned out there was a fiber washer stuck to the bottom of the board, between the nut and board.

              Now I can get to a serious testing and going-over of this thing. Already seeing a couple cold-looking solder joints and some trace lifting. Thanks for hanging with me fellas! Gotta knock this one out, there's a vintage Supro coming in from the local Mom n' Pop music store.
              Last edited by Fred G.; 10-09-2020, 11:28 PM.

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              • #52
                Perfect. Now compare your PCB ...

                https://images.reverb.com/image/upload/s--q6No-dwW--/f_auto,t_large/v1574631407/p7voxkmutupvctit35mk.jpg

                1)
                Click image for larger version

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                Last edited by vintagekiki; 10-09-2020, 11:34 PM. Reason: 1)
                Who does not know and knows that he does not know - teach him Confucius)
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                • #53
                  The insulating (fiber) washer is there to prevent any traces from being shorted to ground via the nut/bolt. It should be put back in during re-assembly.
                  "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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                  • #54
                    OK...I have the board loose. I reflowed all the solder joints - many looked cold, lifted traces, a mess. This pedal still just will not "wah". When I read across the 33k resistor, I got about 30k. No change, there. I'm reading continuity across the inductor, but - wouldn't this indicate that the coil is OK?

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                    • #55
                      If you measure a 33k resistor and instead of a small resistance you get a value of the order of 30k, there is a high probability that something is wrong with the 0.5H coil.
                      Careful on the pins of the 0.5H coil check the resistance.

                      Click image for larger version

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                      Who does not know and knows that he does not know - teach him Confucius)
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                      • #56
                        Yes, I've hopefully been following the guidelines you're providing carefully. I can't help but always keep drifting back to the inductor being faulty, based on the advice I've been getting. The pedal is "working" fine when switched in, except it just refuses to "wah". I feel like I have done every other means of due diligence (jeez, I cleaned and re-soldered EVERY dang contact under the board, fer Chrissake), other than to replace the inductor. Wouldn't a good inductor give a positive continuity reading, though (a beep)?

                        As always, thank you for sticking with me on my questions. BTW, I fixed that solid-state Fender Yale ;-)

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                        • #57
                          My old Vox Wah has exactly the same board and inductor. Measuring across the 33k resistor I get 36R. Out of circuit the inductor would measure the same as
                          the parallel 33k resistor lowers total resistance by only 0.04R.

                          So if you measure 30k across the resistor, it's either not connected to the inductor at both ends or the inductor is open (broken magnet wire).
                          Last edited by Helmholtz; 10-13-2020, 03:18 PM.
                          - Own Opinions Only -

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                          • #58
                            Originally posted by vintagekiki View Post
                            If you measure a 33k resistor and instead of a small resistance you get a value of the order of 30k, there is a high probability that something is wrong with the 0.5H coil.
                            Careful on the pins of the 0.5H coil check the resistance.
                            The resistance of the coil is measured at the pins of the coil (A, B)
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                            Please photo PCB side after the intervention.
                            Who does not know and knows that he does not know - teach him Confucius)
                            Who knows and does not know that he knows - wake him Confucius)

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                            • #59
                              Originally posted by Fred G. View Post
                              I'm reading continuity across the inductor, but - wouldn't this indicate that the coil is OK?
                              Originally posted by Fred G. View Post
                              Wouldn't a good inductor give a positive continuity reading, though (a beep)?
                              Once again, the term 'continuity' is problematic. Did you or did you not measure continuity at the coil? Never mind, that's a rhetorical question.
                              You are not getting the proper resistance reading across the coil.

                              "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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                              • #60
                                ^^^^^^That. I'll add: Often, the coil wire breaks right where it solders into the circuit board and the coil itself is salvageable by adding a piece of lead from the break to the board. I'd remove it and inspect it for breaks.
                                "Yeah, well, you know, that's just, like, your opinion, man."

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