[SlideCube] cube projector question
Fri, 19 Jul 2002 21:12:37 -0400
Hi Tony, (how about that)..I am attaching a discussion that I found on the
web page several months ago that should answer all your questions. If you
are mechanically inclined, you should be able to make the adjustments. Read
all the way to the end. If you find the little gear is broken, email Paul
Jacobs email@example.com who sells the delrin gears.
John is an engineer in Texas who is trying to repair his Slide Cube
Derek is an experienced technician in Canada walking him through the
John: Derek, I'm looking to see if you have an obsolete B&H "slide cube"
projector slide advance motor. The motor is a small "slot car" type motor.
Do you have any leads on where I might be able to locate the motor or
perhaps a used projector I can get to motor out of? Any assistance or
direction you can give me would be appreciated. Thanks
Derek: Hi John- I just got in a "Junker" but haven't had time to
evaluate the parts. I believe the motor is working though. As I recall the
user had shaved away parts of the turntable in a misguided attempt to
improve transport and I can't get a new one.
(The caveat...of course, any advice I give you below is for your
guidance only and I take no responsibility for your ability or inability to
do any of the procedures safely or to obtain desired results..etc, etc.)
Let me qualify something first though. Are you certain that it is the motor
that is at fault (I've only seen one die before) or is it the teeth on the
little (black, or white) gear that it drives and that engages the turntable?
This is more common problem. To check the gear (if you haven't) lift the
top cover to expose the turntable. Note the little silver "finger" that is
resting in one of the slots on the side of the turntable.
When you reassemble, you'll want to fit it in again like that; doesn't have
to be the same slot. Now, with a tiny screwdriver, pry off the c-clip in
the middle of the turntable, note and remove the tiny black washer, then
lift the turntable straight up at the 1:00 o'clock position is the
littlegear. check the condition of the teeth. This gear is still
available, but I don't know the source. There is a company in nearby
Toronto that gets them but they cost a fortune. If needed I can direct you
Now, if you've already gone past this stage and are into the "guts" inside,
I'll assume you've diagnosed the motor correctly. (Check that there are no
loose wires) While you're in there, look essentially in the middle and
you'll see a locking nut on which the shutter blades pivot. This eventually
gets sticky as the lubricant dries up. If you feel adventurous, you can
disassemble the shutters, clean off the old lubricant and use a very light
grease in small quantity when reassembling. If you don't have a very light
grease, no grease is preferable to heavy grease. If you do this, note
carefully the shape and orientation of the two shutter blades. They are not
identical. Also note their position under a crescent shaped metal guide at
the edge of the shutter blades. Remove the nut, then gently lift the
shutter blades, one at a time. Note a small plastic washer under the first,
and usually under the 2nd shutter blade arm (at the pivot point). Note the
order in which they all come off. Clean and, if possible, re-lubricate the
pivot points. Reassemble. Tighten the nut down to the point that there is
some friction, then back it off a little. You don't want to bind the
shutter mechanism. This is all to stop the projector from "skipping" slides
and/or jamming. (They often jam paper mount slides anyway)
When re-assembling the projector, there are 3 things to remember: Be
absolutely certain no wires are pinched between the casing and the mechanism
or inner casing.
It WILL fit together, though it will not appear to until you are
very, very frustrated.
Do not swear in front of the children when reassembling. You will want to.
Now, after all that, if you are certain it is the motor you need, please get
back to me and I'll double check the motor I have and fix a price and
John: Derek, I took it apart further, though I wished I had waited to read
your email as I discovered many of the things you mentioned on my own last
night. Yes, I attempted to remove the black lever. I loosened the mounting
screws of the solenoid and finally determined, as you pointed out, the black
lever was not worth removing. It appeared to move back and forth fine, but
now the unit really 'buzzes" when I push the slide advance button.
I'll tweak the solenoid position to see if I can get it quieter.
Derek: That should do it. You'll have to experiment a little. Look for any
tell-tale traces of the original position, made by the washer under the
adjusting screws. Use that as a starting point. It's a pain to have to
partially reassemble and test and repeat.
John: There also seems to be an adjustment of the shutters that I
haven't quite figured out, but there is an elegant design of an cam adjuster
connecting the metal shutter arm to the black lever.
Derek: I call it the eccentric, below. You don't want to touch that.
John: I suppose if I ever get to the point of getting the turntable to turn
(and stop) smoothly and consistently, I'll be able to appreciate the meaning
of that adjustment.
Derek: All things being equal, and the shutter blades assembled correctly
and closing properly(see below) the eccentric adjusts the blades so that no
light shows through when closed. Very unlikely to need adjustment.
John: I learned the importance of that black lever and the switch position,
this seems very critical (the first time I tried it after reassembly, the
table just kept rotating). I think I have the switch position adjusted
properly now, so the motor shuts off just as the "finger" begins to slide
into the slot.
Derek: You've been having a lot of fun haven't you?
John: I found a potentiometer limiting the current to the motor so I cranked
this for highest motor output and that helped immensely. It still rotates
slowly and inconsistently, so I think a new motor and new potentiometer
Derek: Hmmm...Are the shutters opening/closing easily now? The locknut can't
be too tight. One point of friction that MAY be a problem is where that
eccentric meets the silver lever that pushes the shutters. While I wouldn't
advise adjusting the eccentric, if you can lift the eccentric carefully to
disengage it, clean the little silver "nub" that goes into the eccentric
with solvent (WD40 is fine) on a Q-tip. See if you can get a tiny bit of
WD40 into the "cup" of the eccentric. Again this is usually not a problem
area, but you never know. As for the potentiometer, it's unlikely that it
would need replacement unless you are getting irregular gain from it i.e.
good contact/poor contact at different points.
John: The "finger" that is connected to the black lever sometimes sticks
halfway in the slot so the shutters don't open completely. I cannot find
any additional source of friction in the assembly so I pulled the return
spring and hooked it on the tang a few coils down to give it a little more
force, but this may be contributing to the solenoid "buzz" problem.
Derek: I've had to do that sometimes too, but I'd turn the potentiometer
down a little. Again, only once in a while, do I find one that needs to
have the silver "finger" turned ever so slightly from side to side to fit
into the slot on the turntable. I do not recommend it as you can get it
more out of whack than before. But it may be a last resort. Getthe speed
down a bit and that should do it, assuming mechanism is not binding
Just thought of something- when the shutters close, is there any light
showing through? If so, try putting the blade that overlaps the otherin
position so it is under the other. They may close more fully that way.
John: I really have a lot of respect for guys like you that work on these
elegant mechanical systems. Everything must be timed and adjusted just
right or they become temperamental, but that is the way machines like these
were possible before digital sensors and timers. It's kind of a fun
challenge for me to see if this mechanical thing will beat me.
Derek: Frankly, I hate working on them. They were a good concept, poorly
executed, with quality of parts and assembly going downhill the last few
years of production.
John: I'm going to work on it some more this weekend. Thank you for your
excellent advise. I'll be writing you again when I've done all the
damage... that is... I have explored it further and have decided what to
do with it.
John: Well, the projector works like new now!
Derek: Glad to hear it!
John: I located the source of the friction in the turntable assembly. It
wasn't coming from the turntable itself, it was coming from the motor & gear
assembly. When I originally reassembled it, I used moderate force to push
the motor up against the plastic reduction gear. Since this gear has been
referred to as the "Achilles heel" of the projector I was attempting to
minimize tooth clearance and any premature gear wear.
This preloaded the bearing surface between the gear and spindle causing a
large amount of friction. I loosened the motor and reassembled it using
light pressure on the motor and that speeded things up a lot. I also
discovered that the projector itself contained a "spare" motor. I found an
identical motor in the auto focus assembly.
Derek: That's a new one on me. It never occurred to me.
John: Since this had only a fraction of the mileage and load of the
turntable motor, I swapped them. It may not have been necessary, but it
couldn't hurt. The autofocus motor required a good "solder sucker" to
remove the pool of solder from the PC board holding the motor's solder tabs.
The turntable now turns swiftly and smoothly. Keeping the turntable at a
constant speed, I found, is key to keeping the timing of all the mechanicals
just right. After working on the switch timing a little more and
readjusting the solenoid to remove the buzz, the projector works flawlessly.
I did find that the spring still needed to be stretched and reattached a few
coils down for consistent reliability. The spring may have lost some of its
force from being stretched for so long.
Don't apply much force on the motor to the gear when installing the
Don't apply much force on the motor/gear assembly to the turntable
when installing the assembly.
Don't ever, ever bend the finger that slides in the slot. Be
assured this is not the problem. It will work when the motor speed and
switch timing is correct.
The timing of the lever switch that controls the motor is very critical. It
is adjusted like "points" are (were) in a car's distributor. It must open
(shut off the motor) just as the finger slides off the "ramp" and into the
slot. When it closes is dependent on the motor speed for smooth operation.
Thanks for all your help, Derek!
Derek: You're welcome (but you did all the work.)
----- Original Message ----- From: "to to" <firstname.lastname@example.org>To:
<email@example.com>Sent: Friday, July 19, 2002 3:23 PMSubject:
[SlideCube] cube projector question> MIME-Version: 1.0> Content-Type:
text/plain; charset=us-ascii> > I just bought a used cube projector
autofocus bell and> howell> > Reverse does not work at all just clicks and
slide> moves a little.> > Forward works, but turntable moves slowly.
Sounds> like it might stop at any time. I ran 4 or 5 cubes,> and then even
in forward, it was stopping in between> slides. I turned it off for a
while.> Now forward works as before, but turntable turns> slowly. But it
works I ran about 20 cubes. Reverse> still doesn't work.> Is this a
serious problem? Can I fix it?> > Thanks> Tony> >
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