Bell & Howell 1658 "vibration" sound

[Arnau Pell]

hello friends,
let's see if you can guide me in what could be the problem. I bought a bell howell 1658 in a state of abandonment, I had to change the worm gear and after a little tuning, it seems to work quite well.
The problem that I detect right now is in the sound that it seems to have as a vibration. I've recorded a video that I think might give you some idea of how it's reproducing the sound.

https://youtu.be/giK0VhETBGQ

[Maurice Leakey]

Arnau
The two jockey rollers are not pressing the film around the sound drum. They should be further apart and giving tension.

[Arnau Pell]

thanks Maurice, do you mean these two?

[Lindsay Morris]

That is a VERY common problem with all the TQ3 models.

Neither of the two rollers appear to be moving in that video clip as they should as Maurice says be pressing on the film to make it sit snug around the sound head larger roller which has a stabilising flywheel inside the projector and thus smoothes out the film jerkiness created by the film shuttling thru the projection gate.

Both rollers are spring loaded (inside the case) and share a common shaft assembly thru the die cast housing which over time develops a bit of corrosion and so tightens up on the shaft so the two rollers do NOT snap quickly together when spread apart with your fingers.

It IS a swine of a job to get at that shaft and get some lubrication into it but often can be done by spraying some penetrating oil from a pressure pack with a long nozzle on the can so you can squirt right at the point that the shaft comes thru into the inside of the projector and then work the two roller assemblies fully apart and then fully closed by hand back and forth many many times so that the penetrating oil can get right into the shaft area and re-lube that section.

It DOES take time and I have done it many times quite successfully which is a better alternative to pulling the machine part again.
It helps to give you better access if you remove the flywheel which allows easier viewing of where you are trying to lubricate.
Had you noticed that problem BEFORE you reassembled the machine after changing the worm gear it would have been easier.

Just be careful NOT to squirt the slit lens assembly OR the tiny solar cell chip (tucked in behind the inner edge of the sound drum) that picks up the light variations from the sound track as the oil will severely degrade the high frequency response of the sound system.

Good luck sorting it out.

[Arnau Pell]

Thanks Lindsay, I'll try to lubricate those parts without disassembling, otherwise I'll reopen the projector to get to that area!

[Maurice Leakey]

I remember my engineer saying years ago that when a projector is dismantled to replace its worm gear it was a good idea to check all moving parts whilst access was easy and do any adjustment and lubricate as necessary.

[Arnau Pell]

I have disassembled part of the B&H to access the two pulleys and after disassembling and lubricating I have recorded another video.
I don't see the possibility of leaving the pulleys more open.
Nor if they should work as a block or individually

https://youtube.com/shorts/RMCR7iHCl-U

[Maurice Leakey]

Arnau
I attach a link to the service manual for a model similar to yours. On pages 17 and 18 look at the following :-
A3.6 Auto Thread System General
A3.6.1. Adjusting The Loading Guides
I do hope these will be of interest.
BHTQIII.pdf (film-tech.com)

[Arnau Pell]

Thank you very much Maurice, tomorrow I will try to put it into practice!

[Lindsay Morris]

Arnau,

They look to now be as they should be and when the film is threaded around the sound drum BOTH should press down onto the film so the film then grips the sound drum and the motion of the film thru the projector drives the sound drum and the large flywheel smooths of the jerkiness so as the film passes the scanning slit it is travelling smoothly and your sound then is steady and NOT garbling like as before.

The Auto thread process should push those two rollers apart so the film can go around the sound drum and then once the auto thread function is disengaged both those rollers press onto the film due to the spring tension of those springs and then good sound will result.

Check that when you engage the Auto Thread lever that those two rollers move apart as IF they do not then that is the problem.

[Maurice Leakey]

Lindsay has made things very clear regarding the sound drum area, but I should point out that the whole auto-thread system must be accurately set up.
The photograph appears to show too much film between the top and bottom of the lower sprocket. Film often jumps one frame at this point usually due to a poor splice.

[Lindsay Morris]

Its a bit hard to see the film path from that clip but it looks to me that the bottom loop is contacting the loop restorer roller.. Is that the case ?? as IF it is that will be imparting the flutter to the sound.
Are you able to manually thread the sound drum area so that the tension rollers DO press firmly on the film and the bottom loop does NOT touch the loop restorer roller at all.??

[Arnau Pell]

I've been doing tests these days and in the end I had to give up because I started with more problems (playback sped up, then "the lever" for automatic threading worked like a car or motorcycle accelerator pedal, etc). The person who sold it also had a 1655 that he also bought together with the 1658, so I finally decided to disassemble and "transplant" the mechanism from the 1658 to the 1655 and lubricate the entire system well. Now the sound problem has improved, although from time to time it loses speed when projecting. I will check the electronics in case any solder is weak.

[Lindsay Morris]

The Speed changing could well be a faulty speed controller block...quite a common failure in those machines in Australia...maybe because the temperatures are higher. I doubt that you would be lucky enough to find another newer more reliable unit and I did have a couple of locally made controllers that were a vast improvement over the original B&H units. The guy who made them in Australia is no longer with us so sadly no more available.

It would be worth checking the speed control trim pots in case the 24FPS one is a bit dirty as sometimes a squirt of contact cleaner and a few swipes of the pot end to end sorts out that problem...you could get lucky.
The Speed control block is fairly obvious inside as its a cast aluminium housing and the thing is filled with black potting mix so you cannot get at the actual electronics.. IF you have another B&H it might be worth swapping that over.

[Maurice Leakey]

The TQII 1658 and its brothers was never a very brilliant piece of engineering. It was introduced in 1973 and is now long in the tooth, and its lamp is obsolete.

My suggestion is to either scrap your projector or keep it for spares.

Look out for a more modern TQIII such as the 2585 which was introduced in 1986, it's dark grey, some call it black, and it uses the modern ELC lamp which is relatively cheap and very easy to obtain. I have some of these and I recommend them.

Bell & Howell TQIII Specialist Model 2585 16mm. Sound Projector Help Page (ian-partridge.com)