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Question for the community regarding my old Rodgers 75

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  • Question for the community regarding my old Rodgers 75

    Last fall I obtained an old Rodgers Columbian 75 which was given to me by a colleague. I needed a practice organ to AGO specs at home and frankly, this instrument fits the bill just fine as thoroughly unified and uninteresting as it is (the flutes actually aren't bad for that era of tech). It was in really great shape and I don't think it has seen a lot of use. My organ tech went through it and we made what little voicing adjustment can be made and we had it sounding pretty darned good. The other day I went in to practice and found that the principals sound very faint--barely there. The expression works but when the shoe is in the fully "open" position they are fainter than they would be normally with the expression "closed". My tech is coming out next week but I'm curious to know if anyone has any idea what I'm going to be in for when he checks it out.

  • #2
    it has been 24 hours, the Rodgers repairmen appear taking a day off. I'll chime in as a general old electronics restorer, not a Rodgers expert.
    One thing every old electronic device built after 1960 has is potentially leaky electrolytic capacitors in the power supply, coupling the oscillator and amp sections together, shaping the tone in the post 1968 models. By 1980 a lot of this shaping was done by IC',s not e-capacitors, but they are still in the power suppies to this day. They are full of water, which leaks out past the cracked rubber seals somewhere between 5 and 25 years of age, depending on the quality of the cap. If you don't believe oxygen attacks rubber, look at a 1970 tire on a old bicycle at the charity resale shop or in a junkyard.
    Few repairmen are brave enough to tell a customer the bad news, but to get reliability out of any electronic device past this age, they all have to be replaced. I put 71 in my 1968 organ in 2010. The symptom of fading away when heated up or working only after heated up, are classic symptoms of a dried up cap. Now, a church surplus organ may have had professional maintenance and not every cap in it might be the age of the organ case. It is up to the repairman to take a look and start with the ones that show the signs of being the oldest. I doubt if a Rodgers has the cheapest 5 year caps like this PC mainboard that failed last year. I also doubt if a Rodgers will be old enough to have e-caps marked with the EIA (Electronics Industry of America) date code of YYWW where year is 19YY. The ones you need to look at are tall cans with squares, triangles and circles marking the + parts, or aluminum cans covered in cardboard or plastic sleeves with a + on one end or a minus in balls pointing at the other end. Some also look like grains of rice with a red end, or peanut M&M's, (tantalum electrolytic caps). They all need to go if the maintenance man is not going to make one trip after another.
    I did my 71 caps for $200. I could do it for $100 now I have learned a few things. If you are not overcommitted to school, learning to replace them yourself saves a lot of $60 serviceman hours. There are things only a Rodgers expert can do, but replacing old e-caps is not one of them.
    One possible problem with transistor or IC based organs, is dirty connectors, brass or tin oxydized by time. These can often be restored by unplugging and replugging them. However, these problems tend to occur at start up, and not after the organ has heated up.
    A third problem is animal debris in the expression housing, especially if there is a light bulb and photocell in there. Also, lightbulbs and CDS photocells are 5 to 20 year items, and may also need replacement, besides the cleaning anyone can do.
    Good luck on you next service call.
    city Hammond H-182 organ (2 ea),A100,10-82 TC, Wurlitzer 4500, Schober Recital Organ, Steinway 40" console , Sohmer 39" pianos, Ensoniq EPS, ; country Hammond H112

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    • #3
      Most likely the light bulb for the LDR (light dependent resistor) in the diapason expression circuit, either blown or oxidation in the socket contacts. This is the most common cause of that behavior with Rodgers analogs.

      --- Tom
      Rodgers 660 with additional analog rack sets (practice), 36D/C in digital conversion, Yamaha CVP-107

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