Walt, I don't know how similar your 660 power supply is to my 220, but it more than likely is a multiple voltage supply...mine (Cambridge 220-II) has +15, -15, +12, -12, +5, -5 (all DC). (All are marked on the supply) My 12 volt portion went out..caused when I was troubleshooting a cipher, having the probe slip and short a trace to ground, which cause a trace on the power supply circuit board to fry open, a pass transistor to fail and a resistor to burn up. I don't suspect that on yours, but it would pay off to know exactly what your voltages are, as measured right out of the power supply. If any one is off by 2 or 3 volts it causes problems. I removed my power supply to work on it (all connections are marked...make a map), then when fixed, I plugged it in and set the 12 volts adjust to 12 volts dead on. Upon re-intsalling the power supply, the organ didn;t work.....because the voltage was lower than 12 volts when under load. So I reset for 12 while under load, and it has been working great since. Good luck, and let us know what you find.
Bernie in ND----- Original Message ----- From: "Walt Scrivens" <walts@xxxxxxxx>
To: <analogorgans@xxxxxxxxxxxxx> Sent: Sunday, December 30, 2007 6:38 AM Subject: [analogorgans] Re: Rodgers Specification 990
This is just to embellish on my last message which was a kind of general "Thank You" to the group, here is what I've gleaned so far...When the organ quit working our organist called the man who does occasional repairs to it and the pianos. He indicated that the organ had a "bad power supply" and was not worth repairing. That only serves to challenge me! Having worked with power supplies from my ham radio days, and in TV and computer repair, etc. I am generally familiar with the power supplies of 30 years ago, so I volunteered to "have a look"The amplifiers are in a separate closet, plugged into a live 110v. outlet, and when the console is turned on, the amplifier power transformers are humming happily, and the heat sinks on the power transistors are warm.The lights on the console all turn on, and there is a key switch for "oudoor" speaker selection. Unlike the main power switch, the bezel around this switch does not light up, and when you turn the key, if feels as though nothing is connected to it. Definitely something to investigate there. The Operator's manual, which I have, indicates that this is for an Outdoor Tower Speaker system, which I'm pretty sure we don't have.Good news about the voltages being stenciled onto the PC boards. That will be useful when I get the back off the console (I assume that's where the tone generators are located!)Thanks for the pin-outs on the cables. Once we get this thing working again, it might pay to replace at least the audio cables. They may be original to the organ, and at least they would date to its installation about 25 years ago (we are not the original owners of this instrument.)Since NOTHING works (except the pilot lights) I'm assuming the defective module is in common to all - if it is a power supply would there be one power supply for all the circuitry within the console (The amps each have their own)?I'm assuming that the organ does not have any kind of protective circuitry that would shut down everything for a particular fault.I may go over to the church this afternoon, or possibly Tuesday. I'll get back to the list with a progress report!Again, many thanks to all of you! Walt This list is provided by Frog Music Press at www.frogmusic.com.
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