Getting Inside a Calcutta Harmonium
Remove the two screws shown in the picture along with the decorative cover.
Depending on the design, you may have to remove a block on each side of the keyboard.
Your harmonium should then look like the picture below.
Note the two white angled handles at the back. These hold the keyboard in place. Turn then inward then you should be able to pull the keyboard up and back towards you to access the interior of the unit.
Solving Calcutta Harmonium Issues
When you open the top, you will see the stops (the white squares) for the two reed banks, and in this case, five drone stops.
The manifold channeling air from the rear bellows to the lower bellows is the curved wood piece to the right of center in the back.
(Note that the keyboard has been removed from this unit.)
Calcutta harmoniums have a unique set of maintenance issues. The keyboard mechanism is more complicated on scale-changer keyboards. The keys pivot on small pins with the far end underneath a separate 'lifter' that, when a key is pressed, allows air to flow over the associated reeds for that note. The left picture above show the keys and lifters in the proper position while the picture on the right shows the keys above the lifters, which is not the correct position for playing.
Calcutta harmoniums have small screws on the end of each key and lifter lever. The key screws adjusts the key arm so that each key caps is at the same level. If this screw is tightened too much, it can cause the lifter to rise up and that the reeds will sound even when the key is not pressed. This is when the screw at the end of the lifter needs to be adjusted.
We need to adjust the tension between each lever to minimize key bounce while also insuring the lifter fully seals the reed holes when the key is not pressed.
Tightening the small screw on the end of the key arm lifts the far end of the key and will decrease the gap between the key end and the lifter. This raises the playing portion (key cap) of the key. Loosening this screw will lower the key cap and increase the gap between the key end and the lifter.
Once all the keys are level, then check for any leaky keys. Open the stops and place a weight (a 9 volt battery on its side works nicely) on the highest key so it is pressed down then start pumping the bellows. You should only hear the notes from the depressed key.
If all is good, then move the weight to the next lowest key and make sure the highest key is not leaky.
Press each key down while pumping the bellows and let the key release. Don’t “slap” the key, just press and gently release. The note should stop fairly quickly and the key shouldn’t bounce. If it bounces a lot, then the spring on that key needs to be adjusted. Some bounce is normal. This is not an easy task so you may want to leave it to me or another repair person.
The picture below shows the locations of the pivot pin slots and also the keys and lifters. The horizontal pins are not visible.
Calcutta Style Keyboard Action
A single key showing the pivot pin
Each key is mounted by pressing the key into a cutout, aligning the pivot pin with a narrow slot and gently pressing down.
Scale Changer Lifter Springs
The picture on the right shows the lifter from the side. There wasn't much room to put my phone in for the picture so it's out of focus. Sorry. The wire spring is secured in the back (left side of the picture) and runs towards the front where a piece of wood with a groove holds it in place. This pressed the lifter down and seals the reed holes, which are covered in green felt.
This next picture shows the front end of the spring which is resting in the slot. This is a very stiff spring, and it if falls out of the slot, it is tricky to get back in. I have found tweezers help along with a small hook made from a large paperclip.
This picture shows the back end of the spring, which is usually secured by a screw which is all but inaccessible without removing the lifter from that key. Pull the spring out of the slot and use needle nose pliers to hold the lifter on each side and slowly wiggle the pivot pin (see picture above) out of the back wall of the tray.