1987 Rodgers 2 manual conversion

I was presented with a mid 1980s Rodgers with the opportunity to do a hauptwerk conversion. This instrument still used analog tone generators as did the previous instrument I am working on, so originally o had thought I would convert as I am on the one from the 60s - strip it down to the switches, and use all new electronics. 

However once I took a look at the keyboards, I found that a serial scanning infrastructure was already in place. 

Upon doing more poking, this serial scanner structure was available for the two keyboards, pedal, stop action and Pistons. Even better, all the wiring was already in place!  So if I could figure out how to replace the computer with a midi interfaced microcontroller, I'd be golden. 

I was able to pretty quickly interface To a keyboard by itself. It is a simple chain of shift registers. The challenge was to figure out how the motherboard was wired for the pedal and Pistons. 

This shows the single board computer plugged into the motherboard. 

After a couple of hours of poking around, I determined how the other two channels of pedal and Pistons were interfaced. On the right you can see two columns of shift registers. One is for the pedal and one for the Pistons. On the bottom is my microcontroller. 

Incidentally, the date codes on the chips indicate that this instrument was built in 1987.

The motherboard interfaced with everything at 12v. Fortunately, the shift registers were all cmos, and after data sheet review and some timing analysis, I determined how fast they could be driven. The biggest reverse engineering issue was finding how the interface between the computer and the shift register chains was made. Rodgers had about 4 levels of buffering. One level, a level shifter, didn't run at speed at 3.3v. So after removing that from the circuit everything worked.

The micro was programmed in assembly, and every byte of memory in the lower page was used. 

The lights interface was not reverse engineered or used, though it works on a shift register principle, but in the other direction. It would be straightforward to implement these. 

After finishing the interface, cleaning up was an order of business. All tone generation and switching circuitry was removed, as well as the inefficient and now hopelessly over specified power supply and amplifier. 

All these boards and associated wiring were removed

Resulting in a much cleaner interior

Showing up is half the battle

I have been burned out on practicing.  Since I played the Edwin Lamar arrangement of "Danse Macabre" in October of last year, I haven't sat down and played for hours.  There are two parts to this issue.  Firstly, I'm distracted by building instruments, and in my work on a major new sample set that I'm trying to get released.  Secondly, and more importantly, I realized that I was caught up in what all the cool kids are playing.  Difficult works by Reger, orchestral transcriptions, modern music...  I've realized that while these can be part of my practice, I do need to work on music that feeds my soul and where I can see progress.  So I learned most of the first movement of the B flat Mendelssohn sonata this morning.  It felt good to sit down for 3 hours and just work on something where I saw progress.  I also went back to my favorite Hauptwerk instrument, the CUI Casavant.  It is a great practice instrument, and since I incorporated a metronome into the sample set, it makes it that much more versatile and appropriate for learning music.

Showing up is half the battle.  Looking forward to showing up by doing something you want to do instead of what you have to do makes it way easier to show up in the first place.

Switches - experience is a great teacher

 Having worked with this style of keyboard on my last instrument, I was better able to work with this one. 

The organ was in a beach community, so there were a lot of sticky keys. I was able to clean the front bushings and coax the openings a bit wider and the keyboards are beautiful right now. I separated the keyboards from the switches this time. It makes it way easier to work on.  

The swell switch matrix is wired. I used 4 to 5 redundant contacts to make up for the low currents.  Fortunately on this keyboard the springs are already soldered so I don't need to go through that messy process as I did last time. 

Cable dressing on this one, based on experience, is much neater than the last instrument. 

Time to order more ribbon cable...

Tone generators

So it looks like essentially it is the equivalent of a 3 rank highly unified instrument. There were 85 notes of "flute"

73 notes of "diapson"

And 61 notes of "Celeste"

Just inferring from the parts, there is a base sine wave generator for the flute and additional filters for the diapson and celeste

These were on 2 racks with the thousands of wire connections.  You can see the 5 octaves of Celeste, 6 of diapson and 7 of flute. 

I'm glad I live deep into the digital age!!

Old time switching

It is amazing the primitive nature of pre digital designs. 

Key action. 

Pedal key action

Stop action (on the keyboards) and couplers. 

It is all about interconnecting thousands of wires. All done in semiconductor logic now. 

I have always held in admiration the scientists and engineers who were able to create television broadcast and receive systems with a handful of tubes and discrete components.

Opus 3 project - Old analog Rodgers Hauptwerk conversion

An old 70's vintage analog Rodgers came up for sale essentially for transportation cost.  I have been looking to try a conversion of an instrument like this.  These old instruments have pretty good bones, with well built pedalboards and wood core keyboards. 

Transportation was something of a challenge, as I had to get it out of there within a day, and no one was available to help.  However with a combination of our awesome hand truck, working out, a disregard for the finish on the case, removal of most of the interior parts, and judicious application of Newtonian physics, I was able to get it loaded into a pickup myself

This console seems well suited to a conversion.  The contacts on the pedal have multiple contacts, so it looks like I won't have to use reed switches.  The keyboards have some sticky keys, which I'll have to figure out, but they are identical in construction to the old pipe organ keyboards I used in my last project. 

First step was to remove all of the old analog oscillators.  These of course are unusable, and have to go to hazardous waste.  Even being an engineer in the field of electronics development, I'm still stunned by the pace of technology.  This was only 50 years ago!!

There is some additional removal of the now overspecified low efficiency power supply and breakout boards.  Once that's done, I can start work on the keyboards, installing ribbon cables as before.

Stop tabs

I finally got the stop tabs from midiworks. But it was worth it for sure. I spent hours before making cables. This time, plug in a USB cable and you are done. 

I got a 7 port hub from monoprice and mounted it on the stop tab board. On the left is the 2 line display. I added 2 switches to be able to control the combination stepper

Mounting and integration will proceed at the convenience of the owner..