With the four unified ranks back online, the rather tedious and time-consuming task of finding all of the notes that do not function correctly begins. Several types of problems encountered so far:
Entire stop not working.
Quite a few of the unified stops were not working at first - normally you can hear the relay behind the keyboard click when you turn the stop on or off, and many were simply not operating. In a few cases, the stop switch itself is not making proper contact and will need to be adjusted or repaired. We quickly discovered, however, that in most cases if we turned the stop on, then manually closed the relay, it would remain on, it just couldn't turn itself on. There are very few friction points, but we tried lubrication to no avail. However, adjusting the voltage up to 15.5 volts did the trick. (The relays nominally work on 14 V.) Hopefully, the relays are just stiff from disuse, and will limber up after a while so that they will operate on 14 volts as designed. The adjustible voltage supply we are temporarily using can only produce enough current to operate about a dozen of the relays at a time, but there are ten times that number in the instrument. We have a 14 volt supply that can produce 55 amperes (that is a LOT of current, by the way), but this is not useful if the voltage is insufficient to switch the relays.
Same key does not work with any stop.
So far, we have discovered two mechnisms by which a specific key does not work with any stop.
The middle C# key on the Solo (top) manual makes a little blip of sound when depressed quickly, but will not remain on. When we lifted the stopboard, it started working properly. The weight of the stopboard (which is considerable) is actually pressing down on the coupler mechanism just enough to prevent the switching bar from remaining in contact with the spring wire switches. When depressed quickly, the inertia of the switching bar carries it just past its "on" position where it momentarily taps the spring wires that have been pulled into position by the stops. The C immediately adjacent has intonation problems for the same reason - the switching bar just barely touches the spring wires, so the "wiping" action that normally makes good contact is missing. (Eventually there will be further explanation, pictures, and hopefully video of this in action.)
At least two notes (I do not recall which at the moment) fail to sound with any stop due to the wiper contact that transfers the 75 volt keying voltage to the switching bar being bent so that it no longer makes contact. (Pictures will be added soon.)
Individual note not working. (The same key plays with other stops, and that stop works with other keys - confused yet?)
There are several things that can cause an individual note not to sound, when one of the two problems above is not the case.
The generator itself is not functioning. Fortunately, this is not common, since debugging the tone generators is a bit complicated.
The cabling has a fault. This could be a broken wire (we've found a couple in the old console cables so far) or just a loose connection.
The coupler mechanism is at fault. Typically, the spring wire for that note and stop is bent so that the switching bar does not contact it as it should.
This page last updated at 1:52 PM on Mon, Apr 23, 2007
CHORD site maintained by Dr. William Park. Please address comments or suggestions to parkw@ces.clemson.edu
