Clive Tobin

Right.

Some days half the cameras on Ebay are misidentified. It doesn't help that Bolex was extremely lax in labeling a camera with the exact model number. They expected every user to be a Bolexophile nerd (like all of us on this forum) :-) who memorized all the features of every variation ever made, I think.

Watch out! If the 10-30 zoom fits, this is an 8mm camera not 16mm. You had best read my "Identifying Your Bolex" section on the website. The linked picture pages also have sidebars about which models take the steadiest movies, which will take either single or double perf film, etc.

Pin 1 is negative and pin 4 is positive. If the camera has the old governor motor, pins 2 and 3 might be wired to pilot and bloop.

If you mean the transistor is bad, this would be an easy fix, except that I think you have to completely dismantle the camera to get to the circuit board. Not that it is any consolation, but these European BC-number transistors are bad news anywhere. I used to have the misfortune of being the one trying to keep a Rank Cintel working, and one of these lousy transistors (BC71 maybe?) would fail about every week. That was even after taking off the front bottom panel so the boards didn't overheat, as secretly and unofficially advised by the Rank sales rep. I started replacing all of them with popular reliable types like 2N3904.

It is unheard of for one of our TXM-24 units to fail. I don't recall ever having to repair the circuit in one. Important: Are you plugging the TXM-24 *DIRECTLY* into the camera body per the instructions, and not just into the handgrip? The handgrip is not wired for crystal. Otherwise: Most likely the crystal-related input transistor in the camera has gone sour (shorted or open) so the camera is just running at 22 or 27 FPS and the TXM-24 has no control of the speed. It is quite common for the Bolex transistors to go bad, they are sometimes bad even in a brand new camera. In this case the Sync Alarm light will be flashing or lighted. If not, perhaps the cable is bad and the unit is not getting power. The TXM-24 has a self-test mode where you leave it plugged in, but switch out of the SYNC position and try various camera speeds; the sync alarm should flash or light in most of them, though it might not light at 24 or 25 if the camera's built in speed governor is set very accurately. If not, the cable or socket is bad and the unit is not getting power. It will not harm the crystal unit to be run in this way. Possibly the TXM-24 has a bad speed switch but I've never run into that.

Um... he said OLD reversal stock. It is probably not forehardened for high temperature processing if made for a process like ME-4, unlike current negative, so will transform in hot fluids with vigorous agitation to dilute Jello.

Nobody asked me for further confusion, but each printer point is .025 log E or 1/12 of an F stop of actual light intensity. Since color positive stock has a gamma of about 3, this 1 point exposure change makes a density change of 1/4 stop in the flesh tone area of the print. Labs generally adjust the overall light so that a Light 24 or 25 across (that is 25-25-25 for Red Green and Blue respectively) gives normal results from a normal original. This is done through changes in the voltage, filters and trims. This is controlled for negative-positive printing with the LAD (Laboratory Aim Density) system which was described in the literature by this forum's contributor John Pytlak.

The claw throw and spacing is optimized for super-8 perforations but will also work for 8mm, it is just moving a bit more up and down than it needs to but this doesn't hurt anything as the claw is not a tight fit in the holes. The centering from the edge is changed for running regular-8. This can be done by moving the claw, or by moving the edge guides. What matters is when the camera was made, not when the film was shot with it, as far as running speed. I think the old design cameras sold in the late 50s may still have run 16 FPS, but any redesigned ones were probably 18. I am not aware of any definitive word on when the change happened for every possible camera brand and model ever made. Shooting at 16 and projecting at 18 is actually a kindness to the audience, judging from the zillions of miles of home movies I have transferred... :-)

It might be brand new, but being perhaps 30 years old the rubber parts may be stretched or rotted, the lubricants turned to stone, etc.

Actually, there was a way for a Bolex to do sync sound. Magnasync used to make the Nomad audio recorder, which was mechanically driven by a speedometer cable from the 8:1 shaft on the Bolex, and mounted underneath it. It recorded on 100 feet of split-16 thin-base fullcoat (8mm wide with 16mm perforations on an 8mm 3" return reel) and was of course mechanically interlocked with the Bolex. You just needed a single clapstick hit at the start of the roll as the film and tape would naturally stay in sync till the end of the roll. I think most users bought the motor drive accessory and copied the narrow thin mag to regular 16mm fullcoat for editing. Unfortunately, as you will no doubt discover, the speed governor in a clockwork camera is not perfectly stable through the run, and in particular the speed drops at the end. So towards the end of a spring wind, the reproduced speech would speed up Mickey Mouse style. (Just one more tidbit from my half-vast useless store of information!)

http://www.tobincinemasystems.com/page24.html

A flash contact gives only one feedback pulse per frame. This is not sufficient for a perfectly stable running speed. The crystal motors and control units we used to make generally had anywhere from 9 to 60 pulses per frame feedback to the control circuit. Too low a sampling rate gives "hunting" with under and over correction of speed errors which are integrated (delayed once removed you might say) from the actual velocity, so the phase shifts back and forth causing exposure changes, with any momentary change in friction. Too high a sampling rate, on the other hand, gives overcontrol and excessive gain of the feedback signal, so the speed cannot be stabilized with any practical lead-lag network and continually oscillates up and down. You cannot just arbitrarily pick a sample rate.

I have taken apart hundreds of projectors to rob parts for our TVT video transfer machines, and have owned numerous ones of various makes, and I have never seen one that changed speeds with format change. All 8mm (and super-8) fixed speed projectors made since the late 1950s have run at only 18 FPS. Dual-8 projectors are highly compromised, usually lacking film sprockets. The lack of feed and holdback sprockets requires high gate tension to minimize the effects of random pull from the film reels. This makes the film perforations wear out faster and the image be less steady. The GAF dual-8 ones use the wrong edge of the film for edge guiding, so any unevenness in the lab slitting of 8mm film will result in worse weave on projection than with an 8mm only projector. On all dual-8 projectors that I have examined, the pulldown claws are not in the standardized position either relative to the projection aperture, which will cause any error in perforation spacing to not cancel out in projection. In summary, for the best results you should use separate projectors anyway. To find out for sure if your projector changes speeds, take off the back and see if the belt shifts position to another pulley pair, or if there is any electrical switching, when you switch formats. You can determine the exact speed by making up some film into a continuous loop of known length and timing how long it takes for X number of perforations to pass through in Y seconds or minutes. 8mm has 80 perforations per foot and super-8 has 72. Then do the math.

Someone correct me if I am wrong, but I thought the potential aging shrinkage of triacetate base film was only 0.2% which should go through most cameras just fine.

They closed down and the merchandise was liquidated years ago.

The NPR has a manual inching knob, since all the original motors stopped at random also. I forget where exactly. The rubber coupling gets old, hard and slick and wants to slip especially if it is oily. You can use an NTSC TV set (with a picture tube, not LCD or plasma type) as a poor man's strobe or checker. Run the camera at 30 FPS with dummy film threaded. Make sure the Sync Alarm light is dark to verify that the voltage is adequate. Point it at the TV showing a picture from broadcast (not your own video tape). The shutter bar should move from bottom to top slowly, in either 8 or 16 seconds (I forget which.) If it holds steady or even moves down, the camera is running slow probably from slippage. If it moves in hops, that is worse. We could make more Speed Checkers if we ever get caught up with orders for our TVT video transfer machines, and if there is a demonstrated demand for them.

They should be able to adjust the load capacitance in their test jig until the crystal oscillates at its marked frequency. However this will incorporate any calibration error or aging drift of the sample into the new one.

If the nameplate says 12 volts, DO NOT plug it directly into 120 !!! This is probably a series wound motor which will actually work on AC or on either polarity of DC, with perhaps not as high a speed available on AC. It is characteristic of this type motor that it will run as fast as it can, depending on loading, such as in a vacuum cleaner. So the speed is controlled only by the camera governor. The motor power is chosen by the designer so that it will not quite burn out the governor in typical use with the design voltage applied.

Sorry, I didn't know my inbox needs to be manually emptied. I'll probably need to be reminded again someday owing to my advancing senility. This is probably a crystal conversion of an old Eclair "CIBLO" governor motor. If you want to run 30 FPS you will probably need a 16 volt battery. 24 FPS should be fine on 12 volts. It does not stop in the viewing position, unlike the later TXM-14 models which did have shutter parking. We used to recommend using our crystal Speed Checker since the NPR (like the Arri 16S and 16M) has a smooth rubber drive coupling that can slip without warning and cause out of sync or flickering footage. (This item is no longer made.) In case of slippage, the motor will be running the right speed but the camera will not, so the Sync Alarm light will not show. The TXM-6 was one of my all-purpose circuit boards that could be strapped to work with various camera models including Arri 16BL. It was likely a current model around 25 years ago. Anything else you need to know about it? As a simple model with only obvious (to me at least) user controls I don't think I ever wrote an instruction manual for it. Manuals that I have been able to find are posted on the website.

The EBM does not have any mechanical release parts, it is started and stopped by just switching power to the built in motor, so it stops in a random position of the shutter. It can be driven through the shaft without difficulty as far as I know. The internal motor will just coast in this case. The EL shaft is there, I suspect, because it is part of the usual Bolex pulldown claw and gear mechanism and it would cost more to eliminate it than to just keep it as is. I am not aware of any official Bolex accessory that would fit.

I think the 25 FPS crystal is 1.000000 MHz while the 24 FPS one is 960,000 Hz if I remember correctly, both a very poor choice by modern standards. The crystal itself is likely in an HC-6 (large) case and potted in glue, wax or something. Crystal manufacturers generally refuse to make crystals for under 1 MHz as they are large, delicate, unstable, unreliable and expensive. A technically much better approach would be to use one that is 4 8 or 10 times the frequency and digitally divide it by 4 or 8 or 10 as appropriate. 3.84 or 7.68 MHz are common microprocessor accessory frequencies and you can buy a crystal off the shelf from many distributors for well under $1. However this would require camera motor modification to feed power to the external crystal, oscillator, divider module. If you can get a 960 kc crystal made, they will want to know the circuit parameters, that is series or ? pf parallel resonance. I can't find my drawings or I would try to figure it out for you. Custom crystals are made by outfits such as Jan Crystal, Crystek, Northern Engineering Labs, etc. You may have to beg and plead to get them to make this too-low frequency. Yes, I know there are lower frequency crystals made such as 32.768 kc for quartz watches but these are a different cut. The space in between these frequency ranges is a no man's land.

I think the Pan Cinor 85 had a focusing aid (center groundglass or split image), but the 70 did not.

I have a couple of 1800 RPM sync motors with capacitors that were scrounged from old Sony 3/4" U-matic decks. I don't recall what direction they turn in. What direction does your motor drive shaft need to turn? Specify whether this direction would be looking at the camera or looking at the motor. I will sell these cheaply.