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The impossible happens every day

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  • The impossible happens every day

    Two in a week;

    #1. Customer has a Taylor guitar. A local guitar tech replaced the OEM socket with a Switchcraft unit and soldered it to the output PCB. Except the battery -ve was connected directly to ground, meaning it was switched on all the time and ran the battery down in under 2 days. The hot preamp output was connected to ring, and the tip grounded. So no output possible. Except, the owner claimed to have done two gigs with the guitar like it was, then it suddenly stopped working. I suggested maybe it could have worked if the plug was inserted just enough to engage with the socket 'ring' connection, but he said no, it was plugged in all the way and worked fine.

    #2. A desk fault burnt out the ground tracks on a Sansamp RB1 rackmount preamp, used with an SVT4 Pro. Preamp repaired and tested and returned to the customer. He did one gig and said it didn't work. I apologised and took it back for a second look. Worked perfectly, but I opened it up and checked the signal path, connections, socket contacts and pots to be certain I hadn't missed anything. Rang the customer and asked him how he connected it and he said; bass plugged into SVT, SVT Pre out into RB1 return, RB1 send into SVT Power Amp In. This allows him to blend the straight amp sound with the RB1. I said it can't work this way - the only way a processed signal can output from the RB1 send is if there's something plugged into the RB1 input. He wasn't having any of this and insisted that it had been running like this for three years. I suggested he bought his rig round and we set it up as he though. It didn't work but he still maintained that it always did. Anyhow, I connected it up as I though it should be; bass into SVT, SVT FX send into RB1 rear input, RB1 'Sansamp' output into SVT FX return. Now everything worked as it should. He still wasn't having it. He did a gig two days later and rang me to say it worked perfectly and couldn't understand how it worked before.

    The answer is simple; it didn't. I said it was like taking a car with no engine to a garage and saying you'd been driving it round fine like it was.

  • #2
    #1 - shortly speaking: hot wire was exchanged with the shield. This could work - at least with passive guitar, assuming that you ignore increased hum.

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    • #3
      The ring shorts to ground when plug is inserted, though. Barrel is grounded.

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      • #4
        You have my sympathies. Been there. Thank whatever gods may be that most customers are not quite so sure about areas they understand so little about .

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        • #5
          Well, I admit to finding myself under similar types of misapprehension, and realising that the way I thought something was couldn't have been possible; so no stones will be thrown from this glass house.
          My band:- http://www.youtube.com/user/RedwingBand

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          • #6
            Not sure about your clientele or area, but I've worked in several where plenty of the "musician" types needed to "get off the pipe".
            With my current area & clientele, it's more likely old age related.
            Originally posted by Enzo
            I have a sign in my shop that says, "Never think up reasons not to check something."


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            • #7
              Originally posted by g1 View Post
              Not sure about your clientele or area, but I've worked in several where plenty of the "musician" types needed to "get off the pipe".
              With my current area & clientele, it's more likely old age related.
              It goes something like this. Did you put a fresh the battery in your guitar ? What battery ? Oh yeah the battery. Yeah I put a fresh one in. Did you buy the battery recently ? Yeah. I got it it from a friend of mine who said he got it new. (from the pound shop) 5 years ago) So you have a new 5 year old battery and your guitar doesn't seem to work with it ? Lets try putting a nice new battery in. What a surprise it works now. That'll be €15 + the cost of the battery. How much!!!! And don't forget to check the earth/ground on your valve amp while your'e playing in the rain.

              Cheers

              Andrew

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              • #8
                "Alice laughed: "There's no use trying," she said; "one can't believe impossible things."

                "I daresay you haven't had much practice," said the Queen. "When I was younger, I always did it for half an hour a day. Why, sometimes I've believed as many as six impossible things before breakfast."
                Experience is something you get, just after you really needed it.

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                • #9
                  Originally posted by the great waldo View Post
                  It goes something like this. Did you put a fresh the battery in your guitar ? What battery ? Oh yeah the battery. Yeah I put a fresh one in. Did you buy the battery recently ? Yeah. I got it it from a friend of mine who said he got it new. (from the pound shop) 5 years ago) So you have a new 5 year old battery and your guitar doesn't seem to work with it ? Lets try putting a nice new battery in. What a surprise it works now. That'll be €15 + the cost of the battery. How much!!!! And don't forget to check the earth/ground on your valve amp while your'e playing in the rain.

                  Cheers

                  Andrew
                  lol

                  "but the little red light isn't even on"
                  "well a dead battery can cause that"
                  "oh wow really. I have some other batteries but I don't know if they're dead or not"
                  "that's why you have a tongue, the universal tester for the presence of electricity"

                  Double your bench fee, that'll sort the wheat from the chaff .

                  Funny old game eh? Let it be said, though, that I am constantly surprised by the general good nature of my customers, it just throws the occasional richard into sharp contrast.

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                  • #10
                    Originally posted by Alex R View Post
                    lol

                    "but the little red light isn't even on"
                    "well a dead battery can cause that"
                    "oh wow really. I have some other batteries but I don't know if they're dead or not"
                    "that's why you have a tongue, the universal tester for the presence of electricity"

                    Double your bench fee, that'll sort the wheat from the chaff .

                    Funny old game eh? Let it be said, though, that I am constantly surprised by the general good nature of my customers, it just throws the occasional richard into sharp contrast.
                    Hi Alex

                    I've been using the tongue tester for 40 years. I just wonder if it's affected my brain as i'm still in the music business, duh!! maybe i'll try the test on the car battery to see if it works.

                    On with the motley

                    Andrew

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                    • #11
                      Originally posted by the great waldo View Post
                      Hi Alex

                      I've been using the tongue tester for 40 years. I just wonder if it's affected my brain as i'm still in the music business, duh!! maybe i'll try the test on the car battery to see if it works.

                      On with the motley

                      Andrew
                      It works for anything from 5 volts upwards. You can estimate the voltage by trying to speak after applying the test. If the smoke alarm goes off you're probably looking at 200v plus. Apparently the Saudis use nagging wives as testers.

                      Erm, just kidding...

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                      • #12
                        This is a funny topic. Even if this stuff isn't funny when it happens. Recently I had a customer complain for the third time that his amp failed at a gig. Fluctuating volume and ugly distortion. Repeated testing (the previous two times) showed nothing wrong with it. Burning it in, flexing the board, smacking it, wiggling tubes, jacks, switches for many hours showed no faults. I told the customer the problem had to be somewhere other than the amp and he insisted that all his stuff was working fine with other amps. So I kept the amp amp near the bench for over a month. I had to play through it as much as possible trying to induce the fault under actual playing conditions. Not so bad since it's one of my own and I like it. The amp never did fail. I gave it back to him and it's been fine since. He obviously has a bad cable in the mix or the guitar he prefers with this amp has an intermittent fault. He simply wouldn't believe that and never will until his system fails with a different amp. In which case I expect he'll bring that amp in for repair You can lead a horse to water, but you can't make him think.
                        "Take two placebos, works twice as well." Enzo

                        "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

                        "If you're not interested in opinions and the experience of others, why even start a thread?
                        You can't just expect consent." Helmholtz

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                        • #13
                          On the flip side of That Coin: the fact that you could not reproduce the failure does not prove, nor disprove, that there is not or was not some issue with the amp.

                          Just sayin'.

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                          • #14
                            Originally posted by Jazz P Bass View Post
                            On the flip side of That Coin: the fact that you could not reproduce the failure does not prove, nor disprove, that there is not or was not some issue with the amp.

                            Just sayin'.
                            Oh, I'm on board with that! That's why I tested and played the amp for hours and hours. The fact that NOTHING happened means that nothing can be proven or disproven. But this sort of thing can devolve into "Of all the people in the United States that have died, nearly all of them ate peanut butter." Point being, though I was unable to prove the amp wasn't responsible, it wasn't.
                            "Take two placebos, works twice as well." Enzo

                            "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

                            "If you're not interested in opinions and the experience of others, why even start a thread?
                            You can't just expect consent." Helmholtz

                            Comment


                            • #15
                              My heart sinks when I get those jobs. I have one right now - A Hotrod Deville where the drive channel didn't sound as distorted as it should on just one occasion when the footswitch was operated. The owner reports it never did it again but wants a full investigation to make sure it never happens in the future.

                              Hit it, poke it, push, pull, bang it on the bench, gentle pressure, vibration, inspection, measure, test, observe, play quiet, play loud. Nothing.

                              I bet the next time out it will go wrong.

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