This page is to assist professional organ technicians in the field who are engaged in active technical support with us.  This information does not apply to other branded control systems, and no warranty is expressed or implied.

DC instability can wreak havoc on a real-time control system.  Processors need stable sources of power, as do the supporting components.  Many devices rely on having stable comparisons or differentials to produce an expected result.

A vast majority of “weird” problems boil down to being power supply/power wiring related.

If an installed system is being analyzed to find a problem, please try these steps:

  1. Take a volt meter and measure between the (-) terminal of each and every rectifier and check for continuity to earth ground. A connection between them is very undesirable and must be eliminated.  Astron Rectifiers have a jumper internally between the (-) terminal and the earth terminal that must be removed prior to use in a pipe organ.  Contact Astron for assistance with this.  Sometimes, the (-) busses will be intentionally bonded to a building’s electrical system.  This is not desireable and should be removed.  A bond between (-) and earth can come from surprising and unsuspected places such as a PC connected to the organ, audio amplifiers, and even MIDI record/playback units.  This is especially important for intermittent problems.
  2. Make sure that there IS a good bond between the various (-) busses in the organ.  The bond between the console and each chamber is of critical importance.  What sounds like a small voltage difference (2 volts) is enough to cause major problems.
  3. Are your rectifiers big enough? (and the real question – are you sure?)   Look at the driver boards and their fuses in the organ – how much current could the thing consume?  When you first turn the organ on, *what if* every single output pulses momentarily?  You’d never know (the wind isn’t up to pressure), but the current draw is massive.  If the rectifiers are undersized, they could over-react and spike the control system with high voltage when the load goes away.  How often can the control system take a spike like this before failure?  If you need help calculating the size of a chamber rectifier, ask us.  We are more than happy to help.
  4. Use an oscilloscope (set to AC and centered) to watch the power rails while the organ is being played.  If they are moving around, beefier wire or beefier power supplies are in order.
  5. If you have driver cards that are (+) output, make sure the (-) connection is big enough (and the (+) connection for (-) output).  That one connection is handling all the diode supression energy.  If it doesn’t leave through the connection, it will leave through the signal cables.  That is as much of a problem as it sounds!

If a system is still being built, we hope these rules of thumb help you:

  1. In the console, common wires from coils can be connected to a common fuse, but we strongly suggest no more than 10 stops per fuse.  This is a lot of fuses on a larger console, but it also ensures that voltage drops remain minimal.  We also suggest that the wires be brought out of the wiring harness separately and either connected at the fuse (or nearby).  The “common” side of the fuses should have a heavy enough conductor and go to a nearby terminal bar.  Follow the current and make sure all wire is heavy enough.
  2. Solder all “crimp style” connectors if possible.  Only do this with a temperature controlled solution on smaller connections and using a high wattage solution for large connections (rectifier power, for example).
  3. Use stranded wire instead of solid cable.  It may not matter in a tab rail (using Telco cable is fairly common here), but for power wiring, NEVER use solid wire.  Never “tin” the wires before putting them into the screw terminals – they are mean for stranded cable and will only provide reliability to un-tinned stranded wire.
  4. There should never be a positive wire in a console that isn’t fused.  Indicator lights, pedal lights, LEDs, key contacts, pistons, bargraphs, etc. all need fuses.  If it’s a “very light” load, give it a “very light” 1 amp fuse!
  5. Opus-Two input and output cards have fuses on the power input.  This does NOT license the organ builder to omit return fuses (anywhere).  The polyfuses on the Opus-Two cards are meant to protect the card in the event of a driver chip failure.
  6. Stop Actions, Expression blades (pneumatic), and low impedance magnets (Wicks Pedal Actions, for example) should all get SuperDrivers from day 1.



Last updated 4/8/16 JB