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  • Rodgers Cambridge 785



    Hello Everyone</p>

    I've recently acquired a beautiful Rodgers Cambridge 785 organ and would appreciate any advice about setting it up for home use.</p>

    It has 8 channels plus an optional S200B antiphonal amp and came with 4 Walker TP3's, 6 Rodgers 1.7s (Peerless components), and 2 Walker RB 101 subwoofers.</p>

    It's in fantastic condition, very well kept considering it's 1991 install date in the original sanctuary where it's been ever since. The only problem is the 1.7 speakers  (They are showing bad signs of foam rot. Fortunately we've had good luck repairing this problem in our vintage home stereo speakers. We are using the only two of them that still have intact foam. Sadly the foam was so delicate that when these big units were moved from the church's enclosed speaker chamber in the peak of the sanctuary much of the 8' drivers foam disintegrated. Luckly the subs are in great shape as are the Walkers.</p>

    Initially my husband (a somewhat technical handyman) hooked the 2 subs to the pedal channels, 2 Walkers to the positiv channel and 2 Walkers to the swell channel, and 2 of the 1.7's to the great channel. </p>

    As can be expected the organ was way to loud for my home. Hubby said it would strip paint if I used it like that. Even with the pedals closed it was overpowering. So he adjusted all the channel controls on the audio board to middle of their range. (most were at 90% full when we got it). With that adjustment made it sounds pretty terrific and everything works perfectly. But we're not sure what to do next. We do hear a bit of background hiss from the positiv channel speakers when everything is quiet. Is that normal? I'm also hopeful that we can fix all the 1.7's and maybe use 2 of these on the swell and place 2 Walkers on the antiphonal channel instead. For now we've disconnected the antiphonal amp. </p>

    Any advice or spec sheets for this organ would be greatly appreciated. I read elsewhere that RodgersTech has technical information on their older products but I'm not able to access that site. I have a user manual but would like a tech manual to go with it.</p>

    Regards Margo. </p>

     </p>
    ◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢
    Church: Allen Renaissance Quantum Q-325
    Hm: Rodgers Cambridge 785 & Kawai KG-2
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  • #2
    Re: Rodgers Cambridge 785



    Margo,</p>

    I believe this organ is a PDI organ, which means it is a voicable organ. This may be something only a dealer or technician can do, or maybe you can obtain the software to do it.</p>

    As to foam rot, this is a common problem, and especially more so on smaller drivers. The company I worked for, for many years used only foam roll surrounds on 15" drivers, and they last generally around 20 years. For the smaller drivers such as 10" woofers they used rubber surrounds, and hardly ever had failure in over 25 years. It seems that the 5", 6.5" and 8" woofers with foam surround ended up with foam rot in as little as 10 years.</p>

    Ah well, good job security for the service technician - replacing drivers. I have found it cheaper to replace small drivers than to get them re-foamed. For 15" woofers it made more sense to get them re-foamed.</p>

    Rodgers or a Rodgers dealer should be able to furnish you with the schematics.</p>

    AV
    </p>

    Comment


    • #3
      Re: Rodgers Cambridge 785



      Margo,</P>


      That's a nice organ. We service one regularly in a medium-sized church and it sounds awesome.</P>


      Your husband did the right thing with the thumbwheels. With a little trial and error you can determine exactly which wheels do what to which channels, then you can play around with the voicing even more.</P>


      To fully voice it, you need the Rodgers GC-8 device, which only dealers and techs will have. However, you may not need to do any note by note or stop by stop leveling, if it was properly set up by the original installer.</P>


      Supposedly, one can use a software program called GC-10 to emulate the GC-8, but I've tried it and haven't been able to make it work with the older PDI organs like the 785.</P>


      The hiss you hear may be normal, or it may be a sign of impending amp failure. If it fails, you'll need a new one, but they are not terribly expensive.</P>


      You should however have it checked by a Rodgers tech to see if it has any leaking capacitors in the lamp power supply or on the audio motherboard. These should be replaced before they cause expensive damage.</P>


      Best of luck. Enjoy!</P>


      John</P>
      <P mce_keep="true"></P>
      John
      ----------
      *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

      https://www.facebook.com/pages/Birds...97551893588434

      Comment


      • #4
        Re: Rodgers Cambridge 785



        Thanks John and AV</p>

        It is an early digital with Rodgers PDI technology. But what ever they call it you should hear the flutes and trumpets and the harpsichord is to die for and the other stops, oh wow. What a lovely tone. Breathy where it needs to be and clean as well. I'm so happy to have it.</p>

        Al my husband says he's seen capacitor failure in some computers we have had. He says first they bulge and then later leak a crystaline something or other. Would the organ capacitors show the same symptoms? The board with the thumbwheels looks good. Lots and lots of capacitors on it but other than a little dust we don't see anything unusual. Just to be sure is the audio motherboard that which has all the thumbwheels on it? It's labeled Channels 1-8 with 3 controls per channel Level. Base &amp; Treble. (For now he just reset the level controls.) We see the Lamp Power Supply housing but can't easily see the inside. Any recommendations on how to look.</p>

         </p>

        Margo </p>
        ◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢
        Church: Allen Renaissance Quantum Q-325
        Hm: Rodgers Cambridge 785 & Kawai KG-2
        ◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤

        Comment


        • #5
          Re: Rodgers Cambridge 785



          The big flat back-plane board that the audio control board plugs into may have some stand-up filter capacitors on it, blue ones, 1000 mfd @ 35 or 50 volts. Look closely at them to see if any juice is oozing out around their bases. If so, get them replaced ASAP before this corrosive juice eats the traces on the board.</P>


          The lamp power supply is in the console floor and is enclosed in a metal box with some slits for cooling. It is not the really big metal box, that is the 8-channel amplifier. Not sure how it's marked, but you probably should check all the big assemblies in the console floor.</P>


          The lamp supply in particular has some large filter capacitors that in some organs have leaked out enough electrolyte that they destroyed the circuit board completely. At least two of them in my service territoryhave actually caught fire. When they flame up they produce a cloud of acrid black smoke, but usually do not catch anything else on fire because of the metal enclosure. However, once this happens you have no choice but to buy the new assembly from Rodgers and it is very expensive.</P>


          John </P>
          John
          ----------
          *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

          https://www.facebook.com/pages/Birds...97551893588434

          Comment


          • #6
            Re: Rodgers Cambridge 785



            Hi John</p>

            We found the back plane board and I'm going to let my husband tell you what he saw.</p>

            Hello, Al here, Thanks for all the advice John. I see the two big blue capacitors you mentioned. I do not see anything on the capacitors or on their bases and they are not bulging but around them on the board is a barely visible film of something. Reminds me of tuner cleaner that has dried. It's not an ooze and its not juicy. I took a Q-tip and wiped and it does come off but is very thin almost hard to see if it the light is not right. The capacitors are mounted sideways and the film is both above and below the capacitors. If they were leaking I'd think think gravity would not make the film travel up but I don't know if its what you are talking about or just a manufacturing flux. The board doesn't seem to have any ill effects where I wiped it. Can I use an alcohol to clean it off and see if it returns in a few months?</p>

            I haven't attempted to look into the Lamp Power supply. It's on the left side bottom as you are looking at the rear of the organ. If I remove the two side screws holding the box to the console floor will the top come off without me having to take it out?</p>

             </p>

            Regards</p>

            Al </p>
            ◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢
            Church: Allen Renaissance Quantum Q-325
            Hm: Rodgers Cambridge 785 & Kawai KG-2
            ◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤

            Comment


            • #7
              Re: Rodgers Cambridge 785



              Al,</P>


              You're probably safe to just wipe off whatever you see around those caps and then keep an eye on it for a while. If they are leaky, you will soon notice a line of liquid running down toward the bottom of the board. Since you have the blue ones, they are probably going to leak eventually. They are very cheap to replace and not that hard a job either. Just take the audio assembly apart, remove the nuts holding the board down, and pull it off.</P>


              Yes, the lamp supply has a cover that will come off if you remove whatever screws are holding it down. No need to remove the whole thing or even take the connectors off.</P>


              Once you take off the cover, you can look at the big caps and see if there is any sign of leakage. On the PDI organs I've serviced it is immediately obvious. As old as they are, if the caps are going to leak they will have done so by now and you will see it, a big mess.</P>


              Best of luck.</P>


              John</P>
              <P mce_keep="true"></P>
              John
              ----------
              *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

              https://www.facebook.com/pages/Birds...97551893588434

              Comment


              • #8
                Re: Rodgers Cambridge 785



                Hi John</p>

                 </p>

                Al here again.  I've removed the Lamp PS cover and I see 2 very large black capacitors and 2 blue ones just like on the Audio Backplane. The black ones are clean but the blue ones have the same thin film of oil/flux around their base out to about a half inch or so around them. No pooling of liquid but something is on the board. I'm going to attempt to clean the film off both areas. What would you use and how would be best to clean them up? I'm not really expecting any problems as the organ was well taken care of by Daffer Organs of Jessup Md, the local Rodgers dealer. They told me that excepting for some lights and bumpers, and a few pistons over the years the only things of significance that have been replaced is the Card Cage Power Supply in 05/2006 and a S-200 Stereo Amplifier was added for Antiphonal speakers last year.</p>

                Thanks</p>

                Al </p>
                ◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢
                Church: Allen Renaissance Quantum Q-325
                Hm: Rodgers Cambridge 785 & Kawai KG-2
                ◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤

                Comment


                • #9
                  Re: Rodgers Cambridge 785



                  Al,</P>


                  You're probably safe to do what you've done. Just wipe with alcohol or something to get the oily stuff off and then check in a couple weeks to see if it has returned. That might indicate a problem.</P>


                  Perhaps they have already replaced the leaky caps, or maybe this one didn't have them. It was just a certain number of consoles that got out of the factory with these potentially defective caps.</P>


                  Believe me, ifthey were leakingthere would be no doubt about it. It makes a huge mess and the lamp supply will eventually go up in flames. Keep the metal cover on, just for safety!</P>


                  As a matter of routine maintenance and safety, I'd recommend taking the metal covers off the various supplies twice a year and checking for leaking caps, as that is always a possibility in an organ of this age. Inside the cage there is a board with a battery on it, and you might have a look at that one too, in case the battery has never been replaced and may be getting a little flaky on the ends.</P>


                  John</P>
                  <P mce_keep="true"></P>
                  <P mce_keep="true"></P>
                  John
                  ----------
                  *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

                  https://www.facebook.com/pages/Birds...97551893588434

                  Comment


                  • #10
                    Re: Rodgers Cambridge 785



                    I know this is an old thread...if anybody has an early Rodgers PDI organ could you PLEASE post some pics of the electronics? I'm dying to know why these looked like. Apparently they had intel chips on them. Given the rumor that they "slow down" under extremely musical load (lots of notes, lots of stops), plus the fact they had an intelligent voicing interface, I'm thinking they were a pure software synthesis organ, as are all digital organs these days. Certainly, they could easily have implemented this with technology from Roland, who were and arguably still are, the leaders in mass-produced electronic synthesis. Unlike the contemporaneous Allen MDS, which seemed to use a mostly discrete logic architecture as the ADC organs had, albeit with much higher sampling rate, a higher bit depth, and some use of early PIC-like devices for multisampling control. (and the same note/keying backplane, so some ADC boards could work in early MDS organs, although the console was controlled by a microprocessor to allow things like MIDI)</p>

                    </p>

                    Comment


                    • #11
                      Hello John, You were so kind a few years back to help me and my husband setup my then newly acquired Rodgers 785 Organ. It has been a real pleasure to have it in my home allowing me to practice for my many church activities.
                      It went out on me a few months ago because of a loose IC socket and as you previously suggested I had the 4 blue 1000uF and 2 small purple 100 uF capacitors along with the IC socket replaced by a local technician and the organ plays like new again. He said it should be fine again for many years to come.
                      Today we were looking for some new 15" drivers to replace the originals in my Walker 101 subwoofer cabinets. I have two cabinets (1 woofer each) hooked up to the pedal amp module at this time. The old foam surrounds are finally giving out. We were looking at the MCM electronics website to find suitable replacements and what a surprise to see your handle in the comments for the 55-2974 drivers they sell. I would appreciate any suggestions you may have for purchasing appropriate new drivers. The low price of the 2974's causes me to wonder if I should opt for better drivers. I really want my 16 and 32 foot stops to sound properly. Thanks in advance for any advice you may offer.
                      Last edited by MargoT; 02-20-2015, 10:24 AM.
                      ◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢
                      Church: Allen Renaissance Quantum Q-325
                      Hm: Rodgers Cambridge 785 & Kawai KG-2
                      ◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤

                      Comment


                      • #12
                        Originally posted by MargoT View Post
                        Today we were looking for some new 15" drivers to replace the originals in my Walker 101 subwoofer cabinets. I have two cabinets (1 woofer each) hooked up to the pedal amp module at this time. The old foam surrounds are finally giving out. We were looking at the MCM electronics website to find suitable replacements and what a surprise to see your handle in the comments for the 55-2974 drivers they sell. I would appreciate any suggestions you may have for purchasing appropriate new drivers.
                        MargoT,

                        I'm sure John will be down shortly, however, meantime have you considered just replacing the surrounds on your current speakers? I have a fellow who replaces my Allen surrounds for around $35 each, and they work like new. I'm not sure where you're located, but I'm sure John can provide some information/resources in your area for you.

                        Sounds like you have the best of both worlds between the Allen and Rodgers. I hope you can get them replaced soon. Best of luck in your search.

                        Michael
                        Way too many organs to list, but I do have 5 Allens:
                        • MOS-2 Model 505-B / ADC-4300-DK / ADC-5400 / ADC-6000 (Symphony) / ADC-8000DKC
                        • Lowrey Heritage (DSO-1)
                        • 11 Pump Organs, 1 Pipe Organ & 7 Pianos

                        Comment


                        • #13
                          Originally posted by myorgan View Post

                          ...have you considered just replacing the surrounds on your current speakers? I have a fellow who replaces my Allen surrounds for around $35 each, and they work like new.

                          Michael
                          Thanks for the info Michael. Yes we have thought to repair our current drivers, even doing it ourselves with a surround kit, but when I saw how inexpensive the cost of new drivers were I though why bother. We went thru the same foam rot problem with the 4 Rodgers 1.7's that we use on the swell and great, but found excellent replacements for their 8" drivers at MCM for less than $20 each. Other than cost are there other advantages to repairing the original drivers?
                          ◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢|◣◢
                          Church: Allen Renaissance Quantum Q-325
                          Hm: Rodgers Cambridge 785 & Kawai KG-2
                          ◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤◥|◤

                          Comment


                          • #14
                            MargoT; if you value the original sound of your Rodgers Cambridge, recone rather than replace. There are several reconing services I would consider if you don't want to tackle it yourself. Neal's is my first choice: http://www.nealspeakerrepair.com/about.html

                            . . . Jan
                            the OrganGrinder
                            (Rodgers Hillsboro veteran)

                            Comment


                            • #15
                              Originally posted by MargoT View Post
                              Other than cost are there other advantages to repairing the original drivers?
                              I would say the primary advantage to replacing surrounds is because presumably the organ was designed to use the original speakers you currently have. As you probably know, they each have their frequency response pattern, and the organ's sound was probably designed with those specific speakers in mind (unless they are replacements). That's not to say that another speaker couldn't do a better (or even superior) job. If the replacement speakers have accordion surrounds, they tend to have slightly less excursion than the original foam surrounds, and can thereby move less air. The net result would be that you would have slightly reduced bass response, but nothing that couldn't be overcome with re-voicing.

                              Again, I'll defer to John, as he has experimented (and continues to experiment) with different drivers, speakers, enclosures, and configurations, always in pursuit of a better sound for a particular instrument. I'm sure he can answer your questions in short order as he is familiar with both your organ, your speakers, and the space the organ is in.

                              Sorry I couldn't help more, but I like to reserve commenting further when I know a person with more reliable expertise and experience can provide the best recommendation for you.

                              Michael
                              Way too many organs to list, but I do have 5 Allens:
                              • MOS-2 Model 505-B / ADC-4300-DK / ADC-5400 / ADC-6000 (Symphony) / ADC-8000DKC
                              • Lowrey Heritage (DSO-1)
                              • 11 Pump Organs, 1 Pipe Organ & 7 Pianos

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