Restoration of the individual generator
Disassembly of the Generator
- Some kind of madman pulling
out channel 2.
The 9 generator channels were tackled in
9 after restoration - The
Preamplifier - gone
are the nasty capacitors. There was a massive PCB oil filled capacitor
in the center of this channel. But I suspect the real culprits
of the contamination were the 2 "black tar" capacitors
alongside of the oil capacitor. The
black goo that was leaking out of them
was incredibly nasty.
It had an awful smell and a very low boiling point. If a
near the stuff, it started bubbling like crazy and emitting
these nasty fumes. I never encountered anything like this,
but I knew I didn't want it in my house. To clean the channel
properly, I had to strip it to the chassis. While I was cleaning
the "tar of doom" off of the chassis, I noticed
it had one good quality - It polished the
chassis to an almost mirror like shine. So, I polished the
with descending grades of steel wool. It looked and smelled
much better. The preamplifier is a simple circuit
compared to the rest of the instrument. So I knew at that
point, I had a long long road ahead of me.
Channel 8 before restoration
- There are 36 capacitors beneath the 3 X 12 pole switches.
The wiring harnesses leading to the reeds and oscillators were
composed of cotton covered wire that wreaked
of PCBs. They all needed to be replaced.
Channel 8 after
restoration - The Hex Vibrati - the
6 mechanical reeds in the back housing are always wiggling.They are
engaged through 3, 12 pole switches to each oscillator so that when
you play a chord - each note has a different vibrato rate. Individual
LFO modulation of each note - nice. The red bar starts the reeds
moving manually by a lever on the front panel.
Channel 7 restored - This
is the underside of the twelve oscillator circuits comprising the top
octave tone generators.
This is the top of Channel
7 after restoration - the custom transformers have adjustable
cores that are used to fine tune the instrument. Each compartment
in channel 7 houses a transformer, a tube and a coarse tuning
Channel 6 after
restoration - This channel houses
the twelve VCA's for the top octave. The loomed wire supplies the
signals from the individual envelope generators in the keyboard. At
this pont, I am planning to eliminate the spring connectors and use
circular multi-pin AMP connectors instead.
Channel 5 before restoration.
Channel 5 after restoration -
Each compartment houses a frequency divider tube, a VCA tube and a passive
band pass filter under the lid. The hinge of the compartment has a switch
mechanism that reduces the bandwidth of each band pass filter for the "mellow" setting.
The first compartment has a pair of tubes in it for show. There are 5
channels like this one in the generator, each with 12 compartments, for
a total of 60 circuits. Fun fun fun!
Channel 4 before restoration -
the capacitors and the large resistor mounting bar have been removed.
Channel 4 during restoration -
Here are some of the custom PCB's I made to replace the smashed terminal
Channel 4 after restoration -
This is the underside showing the polypropylene film caps and the
metal film resistors. Many of the capacitors had to be
doubled up to get the correct value specified by the factory. Also,
due to tolerance limitations, all values and combinations of values
had to be selected and verified on a digital capacitance meter.
channels end up using
150 capacitors each.
Channel 3 - during restoration
- This is the chassis of channel 3 before polishing.
The Novachord Restoration Project involves removing all the components,
all the wiring,
removing all the tube sockets, cleaning and polishing the
chassis, installing the reconditioned tube sockets, installing
new wiring, resistors and capacitors.
Why go this far? - The
primary reason I went so far with the cleaning, polishing and rewiring
was to protect
The pre amp and the power amp did have several leaking oil caps containing PCB's.
The entire inside of the instrument was covered with this black precipitate that
had a very unusual smell.
told me not to let this thing heat
up for extended periods in my house without a total decontamination.
To be frank - I didn't want to take a chance with other peoples health. Plus
it looks great.
Channel 3 after polishing
and wiring - A large amount of elbow grease
Channel 2 After restoration -
A light at the end of the tunnel.
Channel 2 after restoration
Channel 1 after restoration -
The next step is to paint the generator frame and assemble the
Assembling the Generator - The compartment
lids are open.
The underside of the Generator
during assembly - The worst is over.
The Generator after restoration -
All ready to go.
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