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Magnetic sound on 16mm projector


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#1 Luigi Castellitto

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Posted 13 November 2017 - 10:15 AM

I bought a Meopta Meoclub 16 Electronic 2.
I changed the motor belt and the exciter lamp, it works, everything is in good condition, works the optical audio, the motor is fluid, the rewinding, the microphone, etc.

The only thing that does not work is the magnetic audio (the projector can also record the magnetic).
What can I do? I've already tried to clean the magnetic head with alcohol, but nothing.
The speakers works (in fact, with the optical no problem), both, the small speaker in the projector and the large in the cover. Speakers "buzzing", but with the magnetic film in projection no sound, not even far.
I noticed that the magnetic head moves well, when I press the button for the optic sound it moves away, when I press the button for magnetic it approach the film.
The adjustment screws have not been touched, there is with the blue paint on top.
I also tried to touch the head assembly during the projection, but nothing. 

 

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#2 Mark Dunn

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Posted 13 November 2017 - 10:52 AM

This works, but it's not recommended, so be careful and do it very briefly. It worked on my Steenbeck. I assume that you have checked the head wiring.

Make sure the amplifier is on. Touch the head briefly and very gently with either a small magnet or a magnetised screwdriver. If there's no buzz as you do so the head isn't working and you will need a replacement.

If it's any consolation, mag stripe is unusual on 16mm.


Edited by Mark Dunn, 13 November 2017 - 10:53 AM.

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#3 Luigi Castellitto

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Posted 13 November 2017 - 05:17 PM

Thanks, Mark, this method you have told me will keep it in my mind for the future, also if risky. Now I have a news:

 

I've "solved" the problem, my carelessness!

I was incapable of what it is, probably, the eraser magnetic head (but I saw two head) and look where the other one is ...
 
Look where the magnetic reading/writing head is... It was hidden beneath the sound drum!
I put a head, a second, agaist the running film and the sound is ok, I don't know if it low or distorted, I did not have time to hear good, and the head is dirty, but it works.
 
Now the problem: if I put it back in (head enters below the drum, because the "base" where it leans contracts downwards with the springs, then it "enters"), where is the "gold" place, obviously jumps off at the first movement, at the first turn of the drum, flies away. Why I not disassemble? Fear of screws in different positions distort audio. Ther are immaculate with blue paint, can you see.
 
If I try to unscrew only the "gold base", stick the head and reassemble it? Will screws of gold base cause distortion? And how can I attack it? With strong glue, since the other head to be glued, or welded? And the way it leans (written TESLA label up or down? I'd say up, otherwise the label would come off with glue or welding, I think) is it important or not?
 
 
Eraser magnetic head (facing upwards):
i1154659_DSC00095.JPG
 
Read/rec magnetic head:
i1154660_DSC00098.JPG
 
i1154664_DSC00100.JPG

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#4 Mark Dunn

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Posted 14 November 2017 - 05:14 AM

Sorry, I don't fully understand your post.

The head is loose. I assume it should be attached to the triangular plate. You will need to remove the plate and work out how to reattach the head, probably with epoxy. Presumably it lines up with the pressing on the gold plate. The head gap should face towards the stripe- it's difficult to tell but I think the gap is facing upwards in the second photograph.

The screws with the blue paint are adjustable to set the head alignment. You will need to adjust them with mag stripe running to get the clearest sound. You will probably need to do this even if you only need to remove the gold plate and not the whole assembly, because the alignment will be altered by the layer of glue.

Sound alignment films are still available but they are very expensive.


Edited by Mark Dunn, 14 November 2017 - 05:18 AM.

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#5 Luigi Castellitto

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Posted 14 November 2017 - 06:04 AM

I removed the platinum gold, and I applied the head. With a type of glue for mechanical tools, I was wrong?
If it not detach, I will remove the head, clean with alcohol and buy the "epoxy" that you are talking about.
Yes, the gold plate have a line (visible in the picture), born from the pressing of the head, for accurately apply the head. But the plate also has large screw holes, form move forward and back the plate in micromillimeters.
Is the distance of the home from the film important in the sense of micromillimeter?


 

 

I applied the head with the label "Tesla" upwards. Do you think that's right? But put it in the reverse can give problems?

 

 

 

Yes, I think that I need to re-align the head with the blue screws, even though I only disassembled the gold plate. I hope that I can do it well. Where can I buy sound alignment films?
The big screw, the lowest in the picture near the loose head, what is it for??
 


Edited by Luigi Castellitto, 14 November 2017 - 06:09 AM.

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#6 Luigi Castellitto

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Posted 14 November 2017 - 08:08 AM

Magnetic sound test film are this: http://www.wittnercinetec.com/testfilme 

Ok, very expensive... But, in case, what would be useful to me of the three?


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#7 Mark Dunn

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Posted 14 November 2017 - 10:07 AM

. Obviously the head gap must be in contact with the stripe- I don''t know the specifics of the projector layout, so only you can judge which is the right way round. I don't know the tolerances, nor what any particular screw does..

Assuming you already have some films with recordings on them you may be able to check the alignment with those. You want the loudest, clearest sound. The head gap should be perpendicular to the direction of film travel-the adjustment will be in that direction.

I'm not a projector technician. I'm just suggesting what I would do. I've replaced the mag head on a Steenbeck with one from a pic-sync and adjusted it by hand using a striped film as a test film.


Edited by Mark Dunn, 14 November 2017 - 10:09 AM.

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#8 Luigi Castellitto

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Posted 14 November 2017 - 04:31 PM

You're not a technician, but you've given me a lot of help, thank you.
Anyway, good news.
I placed the head by removing only the gold plate, I could not touch the other screws, and even reconnect the gold plate screws in the direction they were.
Magnetic head protrudes a bit more than head for erasing, but is normal, it's longer than the other.
 
As you can see and hear from the video, the results are great. The sound is clear, it does not seem distorted (except as it passes on a stretch of burnt film of the film test).
Not very high, not like the optical one, but perhaps the original is so, and for what I have to do is okay. Then ,I only tested the speaker on the projector, I still do not test the cover/speaker.
I would say that I am fully satisfied, now I have to test the recording with external source and microphone.



 

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#9 Mark Dunn

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Posted 15 November 2017 - 05:04 AM

That sounds reasonable, stripe was never "hi-fi", but you could try adjusting the head alignment to see if you can improve it- the sound seems a bit muffled but it could be your recording, or even the original.
A better speaker may help.

Edited by Mark Dunn, 15 November 2017 - 05:05 AM.

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#10 Luigi Castellitto

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Posted 15 November 2017 - 12:15 PM

It certainly can improve, I have to do some tests, but is recorded with a small Sony handycam, also affected by that.
 
Meanwhile, a bad news: It not record. The external sources play well in the speaker, both the microphone and the aux, their volume is well adjustable, and uv meter works; but a mute track is recorded without any sound, even a little noise.
What could depend?
I knew that a magnetic sound head that reproduces well, also rec well, but I was wrong.
 
P.S. Is it possible that the other magnetic head, the one that was not detached, was for rec? That in this model isn't erase magnetic head (the online manual of this model does not have the option to erase)? I don't know if any projector is like this: no erasing head but two head separate, one for rec and one for play.

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#11 Mark Dunn

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Posted 15 November 2017 - 02:03 PM

There wouldn't be separate record and replay heads in a projector- the sound advance is 28 frames, so one head would have the incorrect advance.

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#12 Luigi Castellitto

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Posted 15 November 2017 - 03:49 PM

Just observation, Mark.
 
Meanwhile, I tried your method, of the magnet (I use a magnet screwdriver) on projector in ON, on both magnetic heads, for only one second, of course.
The one that was detached and I re-assembled makes the "bump", the other magnetic head not.
If that's for the erase maybe don't have to do the "bump", I do not know.
But no problem, if that is for the erase, and it does not work, can always be erased by recording over a mute track.
The problem of no rec is in re-assembled head or in other place of projector.

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#13 Mark Dunn

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Posted 16 November 2017 - 05:51 AM

No, I don't think the erase head would pop.
Presumably there's  a  problem switching from replay to record, but I don't know what it might be.

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#14 Mark Dunn

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Posted 16 November 2017 - 06:26 AM

I suppose the head could still be faulty, but I'm told they are very reliable, and they either work or they don't. If the VU meter is working, and you can monitor inputs, then it sounds like a switching problem. If it's a mechanical problem you should be able to track it down.

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#15 Luigi Castellitto

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Posted 16 November 2017 - 06:27 AM

I'v read on forums, even if about Super 8, that if play is ok but not the rec  that it's possible a problem of internal circuits. If so, I miss it, I'm not expert, and send projector for repaired (if experts want or can) is not convenient for shipping costs too high.
Instead, if is a fuse to be changed or like it, I can do it, but I don't know electric world. In the manuals online are the electrical diagram, but I don't understand anything.

Instead, I have a doubt: the alignment or the distance of the magnetic head could create the problem? Even if I see an improbable hypothesis...


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#16 Luigi Castellitto

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Posted 16 November 2017 - 06:33 AM

Yes, it seems strange also to me that the head is "half-defect", play but not record.
 

Yes, the vu muter work perfectly, and I can monitor the external sources, microphone and aux audio (are in two separate connectors, and with the aux I tried to record from PC and from magnetic recorder) come to speaker high and very clear.

For a mechanical problem that you mean?

Thank you for your support, Mark!


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#17 Mark Dunn

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Posted 16 November 2017 - 07:37 AM

Yes, it seems strange also to me that the head is "half-defect", play but not record.
 

For a mechanical problem that you mean?

 

The projector switches to "record" at some point. On my Super-8 projector it happens when you move the selector switch to "lamp" and hold down the "record" button- the heads then move onto the film. There must also be an electrical switch to enable recording but I can't see how that works. I assume it's inside the selector switch itself.


Edited by Mark Dunn, 16 November 2017 - 07:40 AM.

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#18 Luigi Castellitto

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Posted 17 November 2017 - 05:46 AM

In my Meopta I have to press two button at the same time, and rec function should be activated. Then start the projector with lamp or also without, and it rec.
 

I noticed one thing, not positive: when the magnetic normal play function is activated, the "pop" with the magnetic screwdriver is there. When the rec function in activated not...
I do not know if is normal, but maybe it's a sign that it does not
activate the right circuit of rec.


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#19 Luigi Castellitto

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Posted 17 November 2017 - 06:00 AM

This is the manual (in French, online doesn't in English). The recording function is on page 17.

http://www.meoptahis...SP-pdf-1626.pdf

 

Another thing: when I press the buttons for record, then I don't hear the sound from external source, I have to moderate the volume only by the vu meter. But the manual seems to confirm that this is normal.


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