Forum Top Banner Ad


Ebay Classic organs



No announcement yet.

Rodgers Cambridge 220 || HELP Stops are on when they’re not supposed to be

This topic is closed.
  • Filter
  • Time
  • Show
Clear All
new posts

  • Rodgers Cambridge 220 || HELP Stops are on when they’re not supposed to be

    Hi everyone,

    I'm new here so I'm not totally sure on what to expect so please bear with me :) A friend gave me his Rodgers Cambridge 220 || a while back and it's been fantastic so far (Two manual, pull out stop arrangement 1973). Recently I've noticed that the Hohlflüte stop is always on now, even if I haven't pulled it out. I do have the owners manual with schematics but honestly I have no idea where to start to fix this particular problem. If anyone has any advice on how to manage this that would be greatly appreciated! Thanks!

  • #2

    My first question would be to ask if the Crescendo pedal is open at all? If so, the Hohlflüte stop is one of the first engaged. Other than that, I would defer to our Rodgers experts here on the Forum (i.e. Toodles).

    Welcome to the Forum, and I hope you continue participating here long after your problem is solved.

    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


    • #3
      Evan, I had a similar problem once. Michael's advice is good. I know from experience :embarrassed:
      Eric Mack
      Rodgers 340 S/N 34341
      Los Angeles, CA


      • #4
        I have worked on two of your model and found what Michael suggested. The first two stops wired to the Crescendo pedal to be touching together causing both stops to be on all the time. Take a close look and see if you don't have the same problem.

        Michael (2)


        • #5
          I have a giant Specification 990 that was brought to its knees by the same issue, and the stop that it decided to continually play was a fractional. So if you attempted to play the manual that stop was on and add several other stops it all sounded just awful. It took my electrician a lot of detective work and measurements but he finally isolated a bad resister. Once he replaced that resister, all was right with the world.
          Until The Next Dimension,
          Admiral Coluch.

          -1929 Wangerin Pipe Organ Historian
          -Owner 1982 Rogers Specification 990


          • #6
            Agree on the Crescendo issue, check that first.

            If that's not it, then the likely culprit is the transistor switch for that stop. The switch is driven by the drawknob switch (which could be bad, but that is really unlikely). There are a two diodes and two transistors in the overall switch, and the R66 level-adjust pot. If one of the two diodes has gone out, or the pot has been badly misadjusted (or broken), it could force the two transistors (Q62 (NPN, usually with a bit of white paint on the top if it's the original), and Q63 (PNP) to turn on, activating the stop.

            I believe the 220 service manual has an error with regard to Q63 but I have no way to verify it. The 330 apparently has a similar error in the same type of circuit (nearly identical circuit, in fact). Q63 is supposed to be (by drawing and by circuit arrangement) a PNP transistor, but the schematics show the part number as an NPN part number. If the transistor is original and if I recall correctly, it would have a green paint spot on the top if it's a PNP. Obviously, these are not interchangeable. If the parts are not original, they may have been replaced with a 2N3707 (for the NPN), and perhaps by a 2N4058 for the PNP.

            If anybody can confirm the 220 and 330 service manual potential NPN/PNP mis-numbering, I would appreciate it (for my 330 notes). Better yet, if somebody could post a complete Rodgers transistor part number to common 2N part number cross reference listing (some part numbers are not reflected on the small table at the bottom of some schematic pages), that would be a tremendous help!


            • #7
              Here is what I have on Rodgers semiconductor replacements. Newest data is at the back, so you might start there. This is a compilation of several different Rodgers Field Service Bulletins.
              Attached Files