Mr Pudding

The rocker-tab bar is now with the joiner. He doesn’t think it will be a big job, but I also need to send him some veneer to apply. Naturally enough, I don’t have quite enough veneer remaining, so I’ve had to order another batch. Grr.

Meanwhile, here is what the back of the organ currently looks like. It’s mostly so that I have a reminder of what is going where, but others may find it instructive.

• Red: The brains. This is the board which actually sends (and sometimes receives) MIDI messages. All of the components which will send events to Hauptwerk go through here.
• Green: The keyboards. There are three physical keyboards, and they are plugged in here.
• Yellow (not shown): The pedalboard and expression shoes. This module is actually on the pedalboard itself, and connected by a long wire.
• Blue: Thumb pistons. All of the pistons under the keyboards go through this module.
• Orange: Lamps. This is a MIDI-IN module, and turns various lights on and off when it receives the appropriate MIDI signal: the rocker tabs and the Solo indicator.
• White: Toe pistons. Like the thumb pistons, but for the feet.
• Dark purple: Rocker tabs. These are on-off signals from the rocker tabs.
• Light purple (not shown): Various switches and pots on the console – they were already there, so they can be wired up if I can come up with a good reason for them.

Also not shown in this photo are the drawstop subsystems, which are in/out components. A MIDI-OUT message is generated when pulling out (or pushing in, for that matter) an individual stop, but MIDI-IN messages are also received and activate the individual drawstop solenoids. This means that depressing a thumb- or toe-piston can change the registration mechanically.

The next job, while I’m waiting for the rocker-tab bar to be returned, is to wire up the toe pistons. Once that’s done, the organ will theoretically be playable through my laptop, at least in a small way.

I have two banks of rocker tabs from another Wyvern instrument, making 32 tabs in all. This will give me more options for coupling than I can shake even a very large stick at:

These will sit across the top of the swell manual, directly underneath the music stand. I think this is an American style, and I rather like it.

Here is the moulding which sat atop the old keyboards. It’s about 35mm too narrow, unfortunately:

And here is the profile. It is slightly angled, so not a straightforward replacement:

So my next job will be to find a local bespoke woodworker and see if they can make me a replacement that the rocker tabs will fit into. The tab blocks are matrixed, so I also have to design a piece of electronic magic to convert this into discrete outputs. I’m idly speculating about doing it with a Raspberry Pi Zero running a bit of Python, but I might not have enough i/o, The second option is to design a circuit that decodes the matrix using a series of shift registers. The second is probably the cleaner approach, but I like writing Python.

Decisions, decisions.

I keep waiting for something to go horribly wrong.

Following on from yesterday’s success, I was able to confirm today that the reed switches are all behaving properly. This means that both stop jambs are now functional. I still have to program the BBS-1K modules that they plug into, but that’s a trivial detail (he said, sealing his fate). Today’s activity centred around unscrewing the manuals. I didn’t think I’d have to do that again, but there you go.

When I first wired up the manuals, I connected the 0V wire of the LED to the common ground of the thumb pistons. Now I come to actually wire them up, I realise that this is incorrect. The LEDs will be driven by another MIDECO module, via a MIBO-LITE board. This requires the 12V connection to be “always on”, and the 0V connection is made or broken by the MIBO-LITE. This necessitated a quick soldering job on the underside of each keyboard, to break the connection to the common ground and attach a long lead for connection to the module. What larks!

While the keyboards were disconnected, I took the opportunity to screw down the boards which will turn LEDs on and off. Apart from the three on the manuals, there will be another 32 behind the rocker tabs. “Rocker tabs, you say?” (I hear you cry.) More about them at a later date.

David has promised to return the toe pistons Real Soon Now™ and then I should be in a position to make the organ playable again. I miss it.

Early testing suggests that the reed switches are all behaving. More substantial testing tomorrow.

Everything on the left-hand stop jamb is wired up, at least in theory. I have connected the solenoids to the MIDECO modules and tested them. After a bit of reprogramming of all four modules (two for each jamb), I now have programmatic control of every drawstop. After exercising all the stops, I have noticed that 18 of them are a bit sticky. This is caused by cracking of the moulded plastic sleeve around the shank of the drawstop. The trick is to unscrew the shank, shave the sleeve slightly to account for the expansion diameter caused by the cracking, and re-insert. I’ll do that at some point over the weekend, when the conservatory isn’t quite so oppressively hot. Still, at least it isn’t as bad as last week.

Once I have the drawstops all moving nicely again, I must return to the painful subject of the reed switches. Getting the switches on the right-hand jamb working properly was an exercise in pain. I fervently hope that the lessons learned from that experience will make the left-hand jamb easier. If not, I may have to resort to gin and tantrums. I may resort to gin and tantrums anyway.

I have made a start on the left-hand stop jamb. This one has 34 drawstops, and no added extras. Hopefully it won’t take too long to wire everything up, having learned from my previous mistakes, but there will then be a pause until the last order of components arrives from Midi Hardware. Given the ongoing component shortage, this could take until August. Oh well, there are several other things going on at the moment, and I’m not going to be bored.