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  • Intro To Electronics

    One major thing stopping me from working on my Hammond is that I don't truly know what I am doing. I can't read a schematic, for example, and I'm reluctant to start any repair or modification beyond soldering a broken wire (even that gets me sweating!). Can anyone suggest a source for the basics in electrical circuits, etc. that would give me enough practical knowledge to do such things as diagnose and repair my scanner problem or hook up a Leslie connector, create a 1/4" lineout module, replace capacitors, etc. Thanks in advance!

  • #2
    Re: Intro To Electronics



    Practice! That will help get you going. Go down to Radio Shack &amp; buy a couple dozen resistors and one of those generic PC boards with all the holes and foil dots and get busy. Solder all those resistors in place and hone your skills. Solder wire together. If you play other instruments build your own connecting cords. You might consider building a kit of some type to get yourself some experience. Most come with schematics and pictorals so this would help on all fronts.</P>


    Amazon.com has many books on the subject of basic electronics. You might take a look there or at you local library.</P>


    I did a quick google search and there is a bunch of info on the web about how to read a schematic. They are much like road maps, once you know the symbols it gets kinda easy.</P>


    From another post I figured out you have an A101. What difficulty are you having with the scanner? No vibrato, choppy vibrato, loss of volume? There are many of us here who could suggest the fix if we knew what was wrong.</P>


    As for the Leslie, same deal. What model Leslie and are you using a facotory kit?</P>


    Best,</P>


    H101</P>

    Comment


    • #3
      Re: Intro To Electronics



      The first thing you need to do is familiarize yourself with the safety precautions needed when working on the high voltages present in a tube type organ.</P>


      Procure at a minimum a volt-ohmeter. Radio shack or Harbor freight has them. Read how to use it in the instructions.</P>

      Comment


      • #4
        Re: Intro To Electronics

        I have the advantage of having studied electronics. Mostly theory and basics but at least it helps me to understand what I'm doing.
        Is:
        Nord C2

        Was:
        Hammond L122
        Leslie 147

        Website:
        L100 modifications: www.gietek.me.uk

        Comment


        • #5
          Re: Intro To Electronics

          [quote user="fredy2"]


          The first thing you need to do is familiarize yourself with the safety precautions needed when working on the high voltages present in a tube type organ.</P>


          Procure at a minimum a volt-ohmeter. Radio shack or Harbor freight has them. Read how to use it in the instructions.</P>


          [/quote] </P>


          Quoted for truth. There are things are there that will kill youeven after you unplug them. Filter capacitors ontube amps hold a charge for a long time. You need to know how to discharge them.</P>


          I don't know anything about these new TV sets but the old cathode ray tube TV setscould be really nasty.</P>

          Comment


          • #6
            Re: Intro To Electronics



            flapper,</P>


            You do need to do some independent study, if there isn't a night school course you can enroll in. Like the others said, this can be very dangerous - especially with the high voltages in tube circuits. I recently ordered the followingbook and have found it to be a very well-rounded treatment of electronics: http://www.amazon.com/gp/product/007..._ya_oh_product</P>


            There are many web-based tutorials - jsut search for electronics tutorial. I have referenced this one several times:</P>


            http://www.kpsec.freeuk.com/study.htm</P>


            And yes you have to also "learn by doing" - but a tube circuit should not be your first experience! Get familiar with those basic low-voltage learning kits you can buy and build up your technique from there. When you are starting out you will definitely make mistakes. Pros make mistakes sometimes too. You want to make those mistakes on something you can afford to chalk up to experience (not your vintage instrument!).Give it some time and you will know when you have achieved the appropriate comfort level - until then you may want to see if there are any old-world techs out there who can "mentor" with you - they may not teach much about tube circuits nowadays??</P>


            BTW I'm no pro - I learned a lot from reading, experimenting, participating on this forum, and working closely with an "old-time"tech whowas gracious enough to explain some things and share with me what I am sure is just a small part of his knowledge. I still have a lot to learn. I have since met several other old-world electronics guys and always try to respect their knowledge/experience and learn what I can from them. I got into this stuff by necessity to keep my vintage instrument working - but at first I did have the pros work on the organ before I was comfortable enough to handle some of this myself. There is no shame in that -know your limits, and strive to learn more.</P>


            Good luck and hope this info helps,</P>


            -jim</P>
            <P mce_keep="true"></P>
            <P mce_keep="true"></P>
            <P mce_keep="true"></P>
            Jimmy Williams
            Hobbyist (organist/technician)
            Gulbransen Model D with Leslie 204

            Comment


            • #7
              Re: Intro To Electronics



              These should keep you busy for a while:</P>


              http://www.archive.org/search.php?qu...s%20bluetantra</P>


              There are several excellent texts on electronics at this link that helped me quite a bit.</P>

              Comment


              • #8
                Re: Intro To Electronics



                Thank you all for responding. I have done a little soldering and once built a synthesizer from a kit, and I can look at a schematic and recognize what a switch is, etc., but looking at the schematic of my Hammond, then at the bundles of 45 year old wires--where do I start. I can't begin to translate the schematic into the physical manifestation of it. It seems like a trade one would best learn under an expert and the last one close to my location is retired and in poor health. </p>

                I do have a voltmeter and know how to do very simple things with it such as check continuity on a wire. Probably best to just do some study of theory for now.</p>

                I was lucky enough to play keyboards in bands for about 20 years. I just play at home now.</p>

                My organs are an M and an A-100. I also have an XK3 that I used very little as I got it just before I quit playing in bands. The chorus problem on the A-100 is as follows. Recently while playing the organ, the chorus suddenly was not there. I'd been playing half an hour or so, removed my hands from the keys for a few seconds and when I resumed playing--no chorus. I think I had it on C-1. I tried the other choruses and vibratos and got nothing.</p>

                Leslie question: I don't have a Leslie yet. From reading posts I've learned much about which Leslies would be most useful with an A-100. I have the M hooked up to a MotionSound P-145 via a 1/4" lineout put in by my retired tech. It resides with the M in an upstairs room with most of my other music stuff. I would like to find a Leslie for the A, so I've been watching for the past 8 months, to no avail so far. I could use the MotionSound if I hooked up a lineouton the A-100, but then that involves carrying the MS up and down the stairs continually. The A is too large to ever be brought upstairs, so it is the official living room Hammond.</p>

                As for maintaining the organs, it's either me learning how to do it or paying a tech located about 95 miles from here. I haven't even dared ask him what that might cost!
                </p>

                Comment


                • #9
                  Re: Intro To Electronics



                  Heya Flapper!</P>


                  Just keep asking. Curiosity is the key.</P>


                  Go to the forums page and check out Organ repair&gt; electronics. There are some real bright sparks live in there. </P>


                  I'm bugging one right now, he's instructing me how to repair a solid state amp I burned out. His knowledge of the workings of components borders on the mystic arts, it seems...</P>
                  -1958 Hofner 550 archtop guitar -1959 C3 and PR40- -1964 Busillachio Harmonium- -1964 M101-
                  -1967ish Leslie 122- -1975 T500 (modded..chopped, and reassembled!)-
                  -DIY 760 FrankenLeslie/rat hideout-
                  -1980 Electrokey Electric Piano- -Yamaha electric Harmonium (early 80's?)-
                  -1990 Jansen GMF150 amp- -1992 Korg 01W/fd- -1992 G&L S-500 geetar.

                  Comment


                  • #10
                    Re: Intro To Electronics

                    [quote user="flapper"]


                    The chorus problem on the A-100 is as follows. Recently while playing the organ, the chorus suddenly was not there. I'd been playing half an hour or so, removed my hands from the keys for a few seconds and when I resumed playing--no chorus. I think I had it on C-1. I tried the other choruses and vibratos and got nothing.</P>


                    [/quote]</P>


                    Sounds like tube trouble on the pre-amp to me.</P>

                    Comment


                    • #11
                      Re: Intro To Electronics

                      [quote user="bluetantra"][quote user="flapper"]


                      The chorus problem on the A-100 is as follows. Recently while playing the organ, the chorus suddenly was not there. I'd been playing half an hour or so, removed my hands from the keys for a few seconds and when I resumed playing--no chorus. I think I had it on C-1. I tried the other choruses and vibratos and got nothing.</P>


                      [/quote]</P>


                      Sounds like tube trouble on the pre-amp to me.</P>


                      [/quote] </P>


                      If you have lost all signal in with the vibrato effect on (no sound at all) then I would suspect V2 a 6AU6 tube, second from the left as you look at the preamp from the rear. Try switching it with V1, the first tube on the left, another 6AU6. If vibrato works and normal doesn't the tube is bad.</P>


                      If you still have a dry signal but no effect with vibrato on I would suspect the rotor in the scanner is not turning. This would indicate a lack of oil. Did you lube your Hammond when you got it? You can remove the small back cover of the scanner and give the rotor a spin to complete the fix. It's a tight spot but do-able.</P>

                      Comment


                      • #12
                        Re: Intro To Electronics

                        I have signal, just the vibrato/chorus is missing. I got the A from a friend who had just oiled it, but I think he probably just oiled the tone generator, so I try what you suggested. Can I oil the scanner by removing the back cover or is there an oil cup for it somewhere else? Thanks very much

                        Comment


                        • #13
                          Re: Intro To Electronics



                          There is an oil cup on top of the run motor for the motor and scanner. "Just moist" is enough oil here. You don't want the sponge "floating". You can put a drop of hammond oil on each scanner thread to prime the pump as they say. No oil goes in the back door. You will need a small short screwdriver to remove the rear cover of the scanner. Be careful not to bend the center pin/brush contact. You should be able to sneak a pinky or small wooden dowel in there and give the rotor a spin. You can also remove the run motor/scanner assy. for easier access. It doesn't have to come comepletely out so the wiring can remain in place. My method above requires "gremlin fingers" which I developed over many years of mechanical tech work. It will be difficult to restart the small screws in the tight quarters without a steady hands but it can be done and takes less time than pulling the entire assy out.</P>


                          H101</P>

                          Comment


                          • #14
                            Re: Intro To Electronics



                            To elaborate on H101's advice, do not, under any circumstances, ever, bend the pin sticking out from under the scanner cover! </p>

                            what happened with the tube swapping tip?</p>

                            Comment


                            • #15
                              Re: Intro To Electronics



                              JB3,</P>


                              He had signal just no vibrato so the preamp tube would be presumed good.[:)] If you have a loss of signal with vibrato switched on, that is when the tube is suspect.[;)] On to plan B.</P>


                              H101</P>

                              Comment

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