Welcome to Part 2 of my series on questions to ask when trouble shooting. In the first part you asked the question "Is it plugged in?", and you know your power supply is good, you haven't lost ground, and everything is connected, what is next?
2) Is it turned on?
Under this question I would include not just, "Did you turn they key?" (don't laugh, it has happened), and "Did you physically turn on the drawknob?", but also "Does the computer know the organist did something?" and, "Is the circuit board receiving/processing data?".
The first thing you need to do, and it seems rather obvious to state, is look at the hardware. Many of our boards have a green LED on them which will light when processing data. The Console Control Computer (CCC) and Pipe Control Computer (PCC) have 'heartbeat' LEDs, these should be a steady flash. If the flash is irregular or really slow, then that board isn't processing data correctly. The Pipe Driver Board (PDB) usually has an output assigned to come on (connected to the LED) when any stop on the board is also on. The Chimes Driver Board has an LED which flashes when it receives data, or you are doing any on-board configuration. If you see a red LED then there is a problem.
Classic systems have built in diagnostics, these include tests for switch sense, dual magnetics, pistons, and keys. The organist may have told you that the Gamba isn't working, but there are several things between the Gamba drawknob and the chest magnets that could go wrong, this will help you narrow it down. You might as well run them before you call, as there is a good chance I will ask you to run them.
Check the cables, don't assume they are ok. Wires can come loose, they can break, mice can chew or pee on them. There have been a couple times over the years when a service person has called because the console looks good, but the chamber isn't working. I wanted them to check that the data cable from the console to the chamber was good, they insisted it was good, and kept focusing on what was wrong with our computer boards or software. After a few hours they humoured me and checked the data cable. One of the wires on the 12-pin connector wasn't good. If there is more than 1 wire on a connector with the same colour, make sure you didn't mix up the wires. Just because they are the same colour, doesn't mean they are the same thing. On the CCC to PCC data cable, every second wire is black, but they aren't the same black. The black wires are the negative information for the preceding pin i.e., Strobe +, Strobe -, Data +, Data - etc. mixing up Strobe- and Data- won't work.
You may recall in Part 1 I was telling the story of the talent show. If I had known how heavily the judges were going to weigh originality over actual ability, before the contest, I would have improvised some light jazz, rather than play Chariots of Fire.
Next question "What exactly happened?"