Sankyo Digi-Glo clock from 1970s

[N_Cook]

A charming little video of the innards of one

I've agreed to look at /repair? one that is running fast. Anyone
familiar with clockwork mechanisms here? Curious on-demand presumably
battery powered clock-spring winder process it seems.
Not seen it yet, will turn up next week sometime

alt.horology added

I've now got inside this and a bit more info beyond that person's video.
That strange white splurged numbering is real, not wear, in conjunction
with a static black segmented mask gives an odd visual effect between
true minute digit forms.
The teeth are stripped from the 19.6mm diameter plastic cog driven by
the worm drive on the motor. Owner (given in early 1970s and used
continuously since) reported it running noticeably fast before packing
up totally.
The finesse of this escapement is probably that the spring unwinds a
specific number of turns , and so specific time, until the 2 timing cams
align and the motor comes on for that specific number of turns. So the
escapement consistently runs between 2 specific spring tensions and so
on average is more accurate than simple wound clockwork. So no fusee
required,and independent of fading battery power until exhausion point
and no more motor turning.
I suspect the motor became engaged continuously and so winding the
spring to maximum and so running the escapement fast. Whether preceeded
by tooth stripping or that came after motor jamming , don't know. The
motor runs well, now not jammed or constrained by worm and cog train.
The escapement drive cog off this spring seems to take 6 minutes to back
off 1 turn. I cannot work out the double cam action for the motor
switch, whether every 6 minutes of even say 10 times that, 1 hour, that
I don't know. I suspect the whir of the motor once an hour would be the
designed repeat rate , rather than every 27 minutes 22 seconds or
whatever. For every 6 minutes would not require the double cam
mechanism, just a simple single cam.
So if I get this working again it would be a matter of over-riding the
motor switch a bit and measuring the escapement until the 10 spring
turns is in the right range, I suspect something like 20 turns available
in total, but some residual tension has to be there at all times. Plus
the balance wheel spring adjuster for final adjustment.
Just as well I salvaged "useful parts" from scrapped cassette audio tape
machines. A plastic cog of right tooth pitch and axle size is available
to replace the broken one, just requiring a hole made in the disc to
take the spring anchor hook.
There is condensed nicotine goo on the balance wheel etc. I own a small
ultrasonic bath, use that? immersed in what chemical/s to clean off the
nicotine?

[N_Cook]

Post by N_Cook

A charming little video of the innards of one
http://youtu.be/DYoD25BlSM4
I've agreed to look at /repair? one that is running fast. Anyone
familiar with clockwork mechanisms here? Curious on-demand presumably
battery powered clock-spring winder process it seems.
Not seen it yet, will turn up next week sometime

alt.horology added
I've now got inside this and a bit more info beyond that person's video.
That strange white splurged numbering is real, not wear, in conjunction
with a static black segmented mask gives an odd visual effect between
true minute digit forms.
The teeth are stripped from the 19.6mm diameter plastic cog driven by
the worm drive on the motor. Owner (given in early 1970s and used
continuously since) reported it running noticeably fast before packing
up totally.
The finesse of this escapement is probably that the spring unwinds a
specific number of turns , and so specific time, until the 2 timing cams
align and the motor comes on for that specific number of turns. So the
escapement consistently runs between 2 specific spring tensions and so
on average is more accurate than simple wound clockwork. So no fusee
required,and independent of fading battery power until exhausion point
and no more motor turning.
I suspect the motor became engaged continuously and so winding the
spring to maximum and so running the escapement fast. Whether preceeded
by tooth stripping or that came after motor jamming , don't know. The
motor runs well, now not jammed or constrained by worm and cog train.
The escapement drive cog off this spring seems to take 6 minutes to back
off 1 turn. I cannot work out the double cam action for the motor
switch, whether every 6 minutes of even say 10 times that, 1 hour, that
I don't know. I suspect the whir of the motor once an hour would be the
designed repeat rate , rather than every 27 minutes 22 seconds or
whatever. For every 6 minutes would not require the double cam
mechanism, just a simple single cam.
So if I get this working again it would be a matter of over-riding the
motor switch a bit and measuring the escapement until the 10 spring
turns is in the right range, I suspect something like 20 turns available
in total, but some residual tension has to be there at all times. Plus
the balance wheel spring adjuster for final adjustment.
Just as well I salvaged "useful parts" from scrapped cassette audio tape
machines. A plastic cog of right tooth pitch and axle size is available
to replace the broken one, just requiring a hole made in the disc to
take the spring anchor hook.
There is condensed nicotine goo on the balance wheel etc. I own a small
ultrasonic bath, use that? immersed in what chemical/s to clean off the
nicotine?

Anyone know of a repair guide for these clocks,?
generic name for this battery driven clockwork mechanism?

[N_Cook]

Comes apart very easily, under the dust cover
Loading Image...
3 nuts to release the winder section, leaving the standard looking
escapement section in place.
^ marks the final brass cog of the escapement and < is the balance wheel
adjustment arm.
Not the first cog,A that is breaking up but B. This is coaxial to C, but
separate , that engages with the ^ cog. The spring,shown off to the
side, should be in the section between B and C.
D and E are the 2 cams that flip the 2 part single switch S for the
motor drive, another torsion spring coaxial to D and E.
As the motor drive is worm and so locks the drive train, and is the same
cog as advances the cyclometer dial by 1 minute per turn, I've changed
my opinion as to overal function.
The cams switch , S, must switch the motor on once per minute, one
revolution of the E cam and the D cam perhaps relate to the duration of
motor drive. So motor advances the dial round and also rewinds the
spring 1/6 th of a turn of cog C that has 6 fancy shaped spigots that
must rotate the downwards nib showing to the right of cam E? So why such
a long , multi-turn main spring, if only winding/unwinding 1/6 turn each
time frame of 1 minute?
The motor worm engages with A. That section raised off the tray that I
use for working on such mechanisms because the shaft of A protrudes out
of this section, to the cog that drives the minute advancing cog and
pawl in the display section of the clock.

[N_Cook]

A charming little video of the innards of one
http://youtu.be/DYoD25BlSM4
I've agreed to look at /repair? one that is running fast. Anyone
familiar with clockwork mechanisms here? Curious on-demand presumably
battery powered clock-spring winder process it seems.
Not seen it yet, will turn up next week sometime

Can't help with the repair, but wow that thing is weird. I recall a
similar "mechnical" type digital clock that had a complex mechanism to
move shutters back and forth in a 7 segment patterns to display the time.
It lacked the big wheels like this one. I have no idea what company made
this type of clock or when.

I know little about clocks but my favourite escapement is the Congreve,
shame it is the most useless for timekeeping.
Dunked clockwork and motor switch in 3 minutes of meths in the
ultrasonic bath and the obvious nicotine gloop disappeared.
The escapement needs a minimum of 80gm of force on one of those 6
spigots (6mm radius) to maintain function = 4.7x10^-3 N-m ?. So 150gm
minimum for that 8.5mm ext diameter torsion spring looks achievable with
plastic cogs.
I suspect an earlier version used the 3 arm trip that moves the minute
drum, every 1/3 turn,to reset the motor. There is a blanked off section
that protrudes into the motor section which otherwise is not required in
this model.
Perhaps for some reason they had to move to a self-timed motor on-off
timing and so that double cam mechanism in this version

[N_Cook]

I've had it running for over half an hour with one charge of motor wind,
without the double cam system in place. Sounds healthy enough tic-toc,
so I'll next have to see if the once-a-minute rewind mechanism works.
Cannot check the timing of it without that in place , not prepared to
cound tics

[N_Cook]

Has now been running consistently for some hours, with the once a minute
motor drive.
With balance wheel spring adjuster mid position and main spring fairly
loose but enough to drive the escapement, about 2 sec per minute slow.
With the mainspring tight , so having a regular cylinder form, rather
than the sloppy looking form when loose, gains about 1sec per 5 minutes.

[N_Cook]

Operating on battery overnight , so now just fine timing adjustment.
Strange being in a room with a ticking clock. A third/fourth function of
that double cam system, if the battery runs down then the drive to the
escapement is delatched, so the turns on the mainspring are not run
down. Insert a new battery and the motor spins up to recharge the
spring, 1/6 turn and the escapement is reengaged.
Microprocessor designers have it easy these days .
The wonky digits are so that you get a large room display without
requiring large display rings and so large clock.

[N_Cook]

With some final sub-5 degree adjustments to the balance wheel tensioner
, for one thermal time of year , could probably get it to 5 seconds per
day accuracy. What with the 1/6 of one turn of the mainspring used only
and independent of battery state of charge. I reckon as 40mA of current
use one second per minute then with a 4Ah D cell the clock would run for
9 years. The replacement plastic cog is fibre reinforced so perhaps that
one will last another 40 years.
Even the alarm works. Would originally there have been active
flourescent or radioactive numerals? no sign of any "Glo" with no room
light, only illumination is if you switch on the internal lamp.
Just had summertime clocks change here, could not be easier to adjust
this clock, just turn the small knob on the side 6 turns forward or back.

[N_Cook]

Post by N_Cook
With some final sub-5 degree adjustments to the balance wheel tensioner
, for one thermal time of year , could probably get it to 5 seconds per
day accuracy. What with the 1/6 of one turn of the mainspring used only
and independent of battery state of charge. I reckon as 40mA of current
use one second per minute then with a 4Ah D cell the clock would run for
9 years. The replacement plastic cog is fibre reinforced so perhaps that
one will last another 40 years.
Even the alarm works. Would originally there have been active
flourescent or radioactive numerals? no sign of any "Glo" with no room
light, only illumination is if you switch on the internal lamp.
Just had summertime clocks change here, could not be easier to adjust
this clock, just turn the small knob on the side 6 turns forward or back.

From a horologist at Combe Mill centre
http://www.combemill.org/
the separation of winding and escapement sections (1/6 of a turn
business), for better timing, is called a remontoire movement