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Old 1st Jun 2019, 9:27 pm   #41
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Default Re: Bell and Howell TQII 1652 16mm projector

Yes everything is coupled to the one motor. Obviously sprocket 'pips' need to be in the right place in relation to the claw and shutter mech, else if not, it would either not auto-thread properly or you'd end up with too big (or too small) a loop (or loops) and possible film damage. Obviously the sound drum/mech also has to be in the correct place too. All good fun. Yes mine has the slipping fabric belt idea to couple up the take-up.

Hopefully the output transistor is ok, as mentioned above (thank you for those comments). So perhaps there's something gone wrong with the internal conversion of frequency to volts (or current) in the module? Maybe, when I get a chance, I should de-couple the tacho and substitute it for a signal generator and do a frequency sweep to see if anything happens to the motor speed? It may still kick in but at a much higher (or lower?) frequency than it should.
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Old 1st Jun 2019, 10:42 pm   #42
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Default Re: Bell and Howell TQII 1652 16mm projector

As a final test you could run it up on a resistive load (4K7) between pin 1 and 3. You would have to disconnect the Zener from pin 3 and connect it to pin 4 to get the motor running.

You seem to have a large tacho signal so it is difficult to believe this could be a problem although you do say the scope image is when the tacho is disconnected so it would be good to see it when it is connected.
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Old 2nd Jun 2019, 9:34 am   #43
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Default Re: Bell and Howell TQII 1652 16mm projector

Ah thank you both..seems a simple (but ingenious) and safe way..a separately driven take up would probably cause havoc if it went wrong?

There are potting softeners around ..but don't think you need 5 litres here LOL

https://tinyurl.com/y6nwbkmn
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Old 2nd Jun 2019, 10:33 am   #44
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Default Re: Bell and Howell TQII 1652 16mm projector

I wonder whether there is a difference in the formulation of the potting compound and any resins that might be used in the construction of individual components. It would be a pity if it successfully removed the compound but also attacked the component encapsulation, or even erased any markings.

Quote:
a separately driven take up would probably cause havoc if it went wrong?
Havoc is when an unsupervised tower stops taking up at the beginning of a feature, without tripping any guard switches. The show proceeds as normal but the projector dumps the whole movie, up to two miles of film, in a heap on the box floor.
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Old 2nd Jun 2019, 4:48 pm   #45
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Default Re: Bell and Howell TQII 1652 16mm projector

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Originally Posted by vidjoman View Post
That's repairable. Parts are easy to get but it's a dirty job with all that old grease around.
Pity to scrap a repairable vintage item.
Yes, I agree that it is a pity to scrap it, but that is actually what I was considering, as it's a heavy old lump and really shouldn't go back in the loft now it's been brought down. As I was up there clambering about ducking under rafters with it, I was thinking to myself whether I would still be able to be doing this when I'm in my 80s and heaving it down the ladder. Heavy items like this I do place where there's a supporting wall below so as not to cause bowing and cracking of ceilings in rooms below. A few years ago when a former work colleague died suddenly, his wife got three large skips and several helpers in to clear all the old TVs etc., that he had accumulated in the loft of his house. I got to hear about it too late, but I was told by someone that had been there, that some of the doors upstairs in the house couldn't be closed due to the weight of stuff in the loft deforming the tops of the frames - ruin your house with your collection!

Replacing the worm on one of these projectors does look like a mucky job, but probably not as mucky as replacing gramophone springs. I already have another 16mm Bell & Howell projector which I've had for decades and is much older and has manual lacing and dating from the early 40s, which works and doesn't have this type of worm drive to go wrong. As regards to the later projector, although I used to operate this same type in the mid 70s as an evening job showing films to various organisations, I've never actually used the one that I've got, as I never did like the look of that worm drive, and just like the 'vintageness' of the big old black square one that I've got. There's some useful components in this more recent one that I've got that's similar, but older to the one under discussion in this thread, such as valves, output transformer, internal speaker etc. so I probably wouldn't sell it, but I would consider swapping it for some more old films to play on the other projector - any offers? The reality is that I shall chew it over as regards to the future of this projector, then after I've fallen over it several times it'll either get broken up and scrapped for its useful parts or it'll end up back in the loft for another time, another day - probably the latter if I'm totally honest. It's in fairly nice condition and has its original padded protective slip on cover, plus there's the large matching extension speaker that goes with it still buried somewhere in the loft. The mains lead with the special plug socket is rather perished and needs dissecting at the projector end and re-wiring with a new cable and insulating for safety, but I see that new ones of these are available on-line for a reasonable price.

Getting back to the OPs projector under discussion in this thread, I've spotted a new replacement part that is possibly a substitute for that speed control module. It says in the advert that it replaces the aluminium block that is now obsolete. I've posted below a picture of the control taken from the on-line advert, also for interest a snap of the innards of my projector for comparison. The last picture is the perished mains connector just to shock everyone (no, not really, I'm sure we've all seen worse in regular use over the years). Yes, I did power it up with it like that, I had to get it in just the right position as all three conductors were bare and I found that the 13 amp fuse in the plug top was already blown, so I replaced it with a 10 amp fuse for possible damage limitation as a temporary measure!

I'll also post a link to the advert for the replacement speed control module. if it turns out to be not applicable to this projector, then perhaps the moderators could eventually remove it....
https://www.ebay.co.uk/itm/New-Speed...4AAMXQQQZR4Yq6
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Old 2nd Jun 2019, 6:17 pm   #46
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Default Re: Bell and Howell TQII 1652 16mm projector

I need to see if I can understand post #42. Perhaps I could just ditch the connector to save fiddling with difficult soldering around the zener(s) and just use some temporary wiring with thick bear tinned copper wire poked into the socket. I'll see. I still need to try the signal generator idea too.

I think the tacho signal was circa 29V peak to peak regardless of whether it was connected to the module or not, but I will check.

Yes that's what I'm worried about - stripping off component identities or even melting them! I my yet pluck up some courage though.

Losing an entire tower's worth of film horrifies me!

Techman, wow, that's a great find. How interesting! Sorry, in my excitement, I forgot to say something about your lump. Yes they are very heavy and may well (if you have enough of them) damage ceilings etc. Your example doesn't look too horrendous to me (as regards a worm gear transplant that is), just keep everything meshed as is (assuming that nothing has slipped), mark everything up and off you go. No sure if you'll need some Bristol Tools however (they looks a bit like Torx, but they aren't - typical eh!).

Thank you again.

Andy
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Old 2nd Jun 2019, 6:26 pm   #47
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Default Re: Bell and Howell TQII 1652 16mm projector

Is that a 2SD970 and a 741 I see on that PCB?
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Old 2nd Jun 2019, 6:33 pm   #48
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Default Re: Bell and Howell TQII 1652 16mm projector

I guess, if it's a 2SD970 in my module, the resistance readings I got between module pins 3 and 4 (out of circuit) make sense as that would be the diode.
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Old 2nd Jun 2019, 7:18 pm   #49
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Default Re: Bell and Howell TQII 1652 16mm projector

I think I have a pair of late (grey, 1980s) TQ III's with that PCB in, rather than the potted module which was used in earlier examples of the same models. Unfortunately I am not near them to check. That and the fact that the terminal layout is identical, support the suggestion that it is a drop in replacement for the module, subject to mounting bracket.
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Old 5th Jun 2019, 9:57 am   #50
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Default Re: Bell and Howell TQII 1652 16mm projector

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Originally Posted by Lucien Nunes View Post
I think I have a pair of late (grey, 1980s) TQ III's with that PCB in, rather than the potted module which was used in earlier examples of the same models. Unfortunately I am not near them to check. That and the fact that the terminal layout is identical, support the suggestion that it is a drop in replacement for the module, subject to mounting bracket.
I once rescued for somebody an old AEI (GEC etc) 16mm projector. To transport it I removed (what I thought) were the rather delicate glass fibre casings.
Now projectors were probably just a passing party trick for AEI which I believe were mainly into industrial electrical solutions, so with casings off, I could not help but admire the engineering and the main motor (perhaps the only one?) which AEI probably used in a lift or something LOL.
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Old 9th Jun 2019, 6:18 pm   #51
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Default Re: Bell and Howell TQII 1652 16mm projector

Well I managed to secure the new replacement speed control module – yippee!!. My sincere and grateful thanks for pointing me in that direction Techman. It does indeed look like it will marry up with the projector’s multiconnector. Not quite sure how to orient it yet (not much wriggle room to say the least!), but that’s to come.

So before I take the plunge and try to install it, I want to have another play with the existing one and report back here. I also wanted to try and sketch out the circuit for this new replacement in an attempt to understand how it works. I must confess to getting myself in quite a mess when trying to trace things out though, and the result is a rather spidery and perhaps not as logical as I could be (sorry), but hopefully it makes some kind of sense to someone. I should of course be very grateful if anyone can point out any obvious stupidities and also help to explain how it works.

I’ve also produced a component listing, although some components are difficult to identify – some diodes (D2-D4 incl) and a green component marked TNR, G820k, 4X1 or TNR, 6820k, 4X1 (Z1). Again, if anyone knows what these might be, I should be grateful to hear from you.

If this module does the job, I’ll feel happier about trying to un-pot the original. I’ll try to sketch that one out too (assuming it’s not all one big IC of some kind). I must confess to being staggered by the dramatic difference in size between the old and the new. I have no idea how Bell and Howell got everything inside the potted version!
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Old 9th Jun 2019, 7:46 pm   #52
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Default Re: Bell and Howell TQII 1652 16mm projector

Sorry, that picture was dreadful. Please try this one ..

Thank you.
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Old 10th Jun 2019, 5:11 pm   #53
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Default Re: Bell and Howell TQII 1652 16mm projector

I was keeping my fingers crossed for you that you were going to bag that unit. Old film projectors are a bit of a minority interest and failure of that module seems to be not that common, so I thought you stood a good chance. I also noted that you managed to get some shuttle claws from the same person. Do you know if these are an item that's likely to need replacement and are they standard over a range of projector models of the type being discussed here?

The reverse engineering of the new board looks interesting and very well done for doing it, and with a good photo of the top and bottom of the circuit board, it may be possible for someone to make a replacement in the future, should another replacement be unavailable.

I hadn't run my particular projector, which is a 156 model from around 1942 (it still has the original power supply square cardboard cased smoothing capacitors in the amplifier) for a few years, but I dragged it out a month or so ago show a couple of films to some visitors and demonstrate the old technology to them. It worked fine until one of the films broke about a quarter of the way in. I've got a few empty spools, so I carried on with the rest of the film, running it onto another reel. It had failed at an old splice that I had made when it broke once before. I seem to remember that there were about four ingredients plus cut up bits of film to make the splicing gum, but where I used to work when I made some up, we only had three of them, so probably why it didn't work so well. Now I don't have access to those solvents, which included Acetone, which I do have a drop of, so I tried it with that, but it didn't work. I was thinking of buying the proper stuff, but a bit of internet research indicates that it possibly doesn't keep too well, and seeing as I only have a couple of complete films at the moment, I wouldn't have a lot of use for it at a tenner or more a time. However, the internet search did indicate that 'Superglue' works well, especially when heat is applied to the splicer. So I tried it with the broken film and it worked well and the film is now all back on one reel. I've got a lot of short lengths of old film that were originally with the old 156 projector, so the other night I set about joining them all together in a usable length, using the Superglue with the splicer and careful and quick use of a heat gun, I now have one long length of film. The film bits seem to be basically from two separate old black and white films which although now wound on the spool the correct way round, are not necessarily in the correct order but at least it now has entertainment value and is usable as a test film, which is why these film lengths were originally left with the projector in the first place.

Below are a couple of pictures, the first showing the cut off remains of all the (most of the) damaged sprocket areas from the spicing fun and the second of the working/lacing parts of the B & H 156 for comparison with the previous two models shown in this thread:-
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Old 10th Jun 2019, 8:47 pm   #54
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Default Re: Bell and Howell TQII 1652 16mm projector

Quote:
Originally Posted by Techman View Post

I hadn't run my particular projector, which is a 156 model from around 1942 (it still has the original power supply square cardboard cased smoothing capacitors in the amplifier) for a few years, but I dragged it out a month or so ago show a couple of films to some visitors and demonstrate the old technology to them. It worked fine until one of the films broke about a quarter of the way in. I've got a few empty spools, so I carried on with the rest of the film, running it onto another reel. It had failed at an old splice that I had made when it broke once before. I seem to remember that there were about four ingredients plus cut up bits of film to make the splicing gum, but where I used to work when I made some up, we only had three of them, so probably why it didn't work so well. Now I don't have access to those solvents, which included Acetone, which I do have a drop of, so I tried it with that, but it didn't work. I was thinking of buying the proper stuff, but a bit of internet research indicates that it possibly doesn't keep too well, and seeing as I only have a couple of complete films at the moment, I wouldn't have a lot of use for it at a tenner or more a time. However, the internet search did indicate that 'Superglue' works well, especially when heat is applied to the splicer. So I tried it with the broken film and it worked well and the film is now all back on one reel. I've got a lot of short lengths of old film that were originally with the old 156 projector, so the other night I set about joining them all together in a usable length, using the Superglue with the splicer and careful and quick use of a heat gun, I now have one long length of film. The film bits seem to be basically from two separate old black and white films which although now wound on the spool the correct way round, are not necessarily in the correct order but at least it now has entertainment value and is usable as a test film, which is why these film lengths were originally left with the projector in the first place.

Below are a couple of pictures, the first showing the cut off remains of all the (most of the) damaged sprocket areas from the spicing fun and the second of the working/lacing parts of the B & H 156 for comparison with the previous two models shown in this thread:-
Enjoyed reading your post but I would say that solvents and glue are not the answer. Proper splicing tape is totally reliable and if done properly does not show. Some people have thought it is just glorified sellotape but sellotape is too thick,will go brown and fall apart eventually. The problem with solvents is that it is only really suitable for the old spec acetates and the formulations were changed over the past few decades and of course now it is polyester which does not fuse with a solvent at all but it does not snap either.

Example here.

https://tinyurl.com/y3hahwn3

With splicing tape you cut at the frame edge rather than the sprocket hole (usually with solvents) and if you have the luxury of a Catozzo splicer all the hard work is done for you.
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Old 10th Jun 2019, 9:37 pm   #55
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Default Re: Bell and Howell TQII 1652 16mm projector

I last got some proper film cement , tape splices and white leader from "The Widescreen Centre" , who also still do 8mm and 16mm film. They were in central London 2 years ago but I see that they have now relocated to Ely. Having been located just inside the London congestion zone probably didn't help business. Looks like I will have to use mail order in future.
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Old 10th Jun 2019, 9:37 pm   #56
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The motor pass transistor is on the negative rail (pin 3). Externally the voltages look OK to me so getting to the internals would be the next step!

Pin 1 (39.2/?) = +Power, +Motor
Pin 2 (15.3/15) = +Vcontrol
Pin 3 (0.7/0.3) = -Motor
Pin 4 (0/0) = -Power
Pin 5 (10.8,10.4/10.5) = Control
Pin 6 (9/9) = -Vcontrol
Pin 7 (9/9) = Tacho
The new controller is quite different in design as Pin 4 and Pin 6 are connected together.
Q1 is a regulator. Your circuit is a bit suspect as I would expect the regulated supply to feed pin 7 of the opamp via R125.
Q3/Q4 look like an astable.
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Old 11th Jun 2019, 10:05 pm   #57
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Default Re: Bell and Howell TQII 1652 16mm projector

Thank you for all your comments again. I am very grateful for the tip off and yes I couldn't resist some new claws just in case I need them. I guess they must wear but they are hardened, so I don't know how many operations they need to go through before they go out of shape. Again it'll be difficult setting the shuttle and the in-out correctly without the proper tools or at least a good understanding of where things need to be, but I figured without the replacement claws, if I needed to replace them at any point, I'd simply stand no chance, with or without the special tools.

Splicing is an interesting topic as I think different file stock can (and was) cemented, but other stuff (later, more modern stock) just doesn't stick. That's where 'Quik spices' (if that's what they were called) or the CIR tape and splicer come in. Boy the CIR 16mm splicers are crazy money though.

The 156 looks like it will soldier on forever!

As for the new controller, I need to take a look again. It does look weird how I've drawn it. As regards pins 4 and 6, I figured that the old module probably has these internally connected also (I will buzz them out to see if that's likely), as the lower part of the speed selector assy must presumably have a return to zero volts?

Work keeps getting in the way of play, so I must clear off to the land of nod now (up very early), but I will investigate further and report back. It's a tricky business following the tracks with dodgy eyeballs though.

Regards,

Andy
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Old 11th Jun 2019, 11:30 pm   #58
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Default Re: Bell and Howell TQII 1652 16mm projector

Thanks for this interesting thread. I used to operate a number of B&H projectors for the film club when I was a student in the 1960's but never had occasion to delve into their insides.

I believe that Fuji Single 8 film always used Mylar film base which, being thinner than the normal acetate base, allowed them to have a more compact cartridge than Kodak's Super 8. I think that in the late 1960's Kodak used Mylar for their very high speed B/W recording film (intended for surveillance) to allow about 25 % more film to be loaded onto a standard spool (125' on a 100' spool) but you are unlikely to meet any of this. I think some of Dixons own brand Super 8 used Mylar as well. Only tape splices work on Mylar. I don't know what modern stuff uses: perhaps Fuji use Mylar for their 16mm stock.

The cement splices on some 16mm film I shot at school and as a student in the 1960's are still sound, likewise my 8mm films from the 1970's and 80's.
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Old 12th Jun 2019, 12:45 am   #59
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Default Re: Bell and Howell TQII 1652 16mm projector

Yes, the Fuji single 8 was an elegant sensible, cassette which enabled the film to be backwound for applying effects, etc. The Kodak cassette was a nutjob IMHO, you couldn't do anything with that and the fine focus depended on how well the plastic backplate had been assembled, so today some standard 8 films (with smaller picture area) look a whole lot better than some super 8 films. Quite bizarre why Philips appeared to copy it for their N1500 video system when Fuji appeared to have copied Philips' proven audio cassette design LOL.
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Old 12th Jun 2019, 10:21 am   #60
Lucien Nunes
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Default Re: Bell and Howell TQII 1652 16mm projector

Looking at the voltages and the schematic, I think the difference that PJL spotted is part of the problem with the original module.

The voltage readings show 9V on pin 6, whereas on the new PCB it is connected to pin 4 which is 0V. This would make more sense; pin 6 is a common terminal serving the bottom end of the speed pot and the tach coil, both of which might sensibly be referenced to ground. Two ground pins would be preferable to one, as the connection to the supply carries the full motor current, so you would not want the inputs sharing any common wiring resistance.

I would not be surprised if the fault in the original module was some kind of open or high-resistance connection in the ground rail that has left pins 4 & 6 unconnected, depriving the speed pot of its proper voltage span and the tach coil somewhat floating. Either or both of these would cause the motor to run at max speed. If it were mine, subject to a bit of checking I would probably try linking 4 & 6 at the module pins.

I might have a go at re-drawing that schematic later...
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