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
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