Maida Vale BBC Compton restoration

In the beginning...
The Maida Vale Compton was obtained by Tim Wardley in early 2008 from the Brentford Musical Museum and moved to his workshops in Rochford. Tim then recruited Pat Dunham who at the time was also associated with another of Tim's projects, the Rochford/Kingsway Compton just down the road. At first sight the Console looked great, in exellent condition. It looks like a Compton but has a polished wood finish. Top quality just as you would expect from a BBC commission.

September 08 2008
First look...
The restoration started with a physical examination of the Console and tone cabinets. The instrument is complete and consists of the Console and two cabinets about 6' high and 2' square. The cabinets are connected to the Console by two flexible armoured cables about 2" in diameter, with huge connecting blocks on each end.

Each block has literally hundreds of connecting pins all of which will need to be checked and cleaned to ensure they make contact.

We decided to connect it together and power it up in stages. Once we establish the condition and the degree to which it works we will clean it up, remove the layers of dust, draw layout diagrams and start to restore it.

Console...
The Console gets it's power from the mains and the tone cabinets are plugged into two 5 amp sockets inside the rear cover of the Console. This arrangement doesn't look original and requires the back cover to be unlocked to access the sockets, a clumsy arrangement.

Initial examination of the Console mains wiring arrangements revealed that we will need to renew and modify the existing wiring as the original is to say the least, primitive. There are no fuses fitted so any problems that may arise could cause damage or even a fire!

Inside the Console there is a Mains Transformer rated at 20 Volts 30 Amps to provide current for the Piston Mechanism. This is feeding a huge Selenium rectifier to convert the current to DC. This type of Rectifier is no longer used as modern Silicon rectifiers are much smaller and more efficient. However in the interests of authenticity we decided to test it and use it if it was OK. When they fail it is quite unmistakable as they emit a foul stench rather like rotten eggs.

Tests were done on the wiring to establish that no short circuits existed but we decided not to apply raw mains straight off. We used an old technique and wired a light bulb socket in series with the mains lead. By using different power bulbs the power can be gradually increased and any shorts indicated by the brightness of the bulbs. No problems were indicated so we applied full power. Voltages and temperatures were monitored, no problems arose. We then tested the pistons and found they were in working order although much contact cleaning will be required to make them reliable.

The tone cabinets power take offs were then connected to the Console. Each cabinet contains a 12 disk rotating electrostatic motor driven generator set, a pre-Amplifier, keying relays and the stop switches.

Before starting, the lubricators for the generator bearings were filled with oil (all 28 of them).
The same process using the light bulbs was used to apply power and each one powered up with no problems. We did not try to get the sound working at this stage but the motors ran without any bad noises and the Valves lit up.

There is evidence of considerable modification to the wiring. Indeed some wires have been cut and just left dangling so it will be quite a challenge to sort that out.
There are one or two additions to the component parts that are obviously not original. It will be interesting to see what will happen when we connect an amplifier and speakers. The "Doctor Who" modifications may still work. Very little is documented about what was done and attempts to find out have come to nothing.
It is the intention to restore the organ back to the original specification so the modifications will be removed but documented first.

Sept 10th 2008
Next task was to connect the Console main cables to the Tone Generator cabinets via the big connecting blocks. These cables carry the connections for the Keyboards, the Stop keys and other controls.
The blocks were examined, the contact pins checked for straightness and adjusted where necessary. They were cleaned with a wire brush and the dents in the casings straightened. They were then carefully married up and screwed together.
Power was applied to the Console and the Tone cabinets powered up. To our relief the relays clattered and the Stop rails moved when operated from the Console. At this stage there was no attempt to obtain sound we just wanted to confirm the wiring was basically OK.

We also noticed that the motor on one of the cabinets powered up when the main switch on the Console was operated. This did not happen until after we had connected the action cables. This together with the altered wiring arrangement associated with the Celeste key means that we had some work to do sorting out the power arrangements. It also indicated that the hunch about the Mains sockets in the back of the Console not being original were probably correct.

During the tests we noted that when we operated the "Celeste on Great" key the Tone Generator Motor on one of the cabinets cut out. This has the effect of changing the pitch of the generated notes.

Tuesday 25 November 2008
A red letter day. This is the day we try to actually get some sound from the organ. If successful it would be the first sounds the organ has made for Forty years.
We attached a temporary modern amplifier to the output jack on one of the Tone Cabinets. We decided to video the event for posterity. Watch the Video on You Tube After powering on and waiting a minute for the valves to warm up we selected some stops and pressed the keys. There was a low rumble, there was sound. After some adjustments we had musical notes appearing. Success!!

We still have a long way to go but we now know that we will succeed. The next step will be to painstakingly check and log all the notes not working, trace any poor connections and correct them and overhaul the pre-amplifiers. The mains wiring will need replacing and modern safety fuses fitted.

Friday 1st May
There are two buttons above the Great keyboard marked Sharp and Flat. These are for altering the tuning pitch of the organ to bring it into tune with an orchestra, for instance. In the base of one of the cabinets next to the tone generator motor is a Variac. This is a variable voltage mains auto transformer with the addition of a gear train and electric motor on top. The motor gets it's drive voltage from the Variac.

When we pressed the tuning buttons nothing happened. This could have been due to an electrical fault but we found we couldn't move the gears manually either. We then disconnected the gears leaving the motor free and lo and behold, it then worked. It seems that years of inactivity has allowed the oil and grease to congeal. A good clean will sort it out.

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