8mm Forum: ST-1200HD M & O question

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Posted by Akshay Nanjangud (Member # 2828) on September 15, 2012, 12:37 PM:

I dont have any optical sound films, so am unable to test with film. Please help, I have two questions.

1. When In optical sound mode, is the magnetic sound head supposed to come down and make contact with the film? This is what happens in magnetic sound mode and I feel something different should happen in O mode.

2. The sound when I play M mode is excellent. Having no optical sound film to test, can we guess or check to some probability if the optical sound work too? I hear a hiss from the speaker in both M and O modes.

Posted by Pasquale DAlessio (Member # 2052) on September 15, 2012, 01:16 PM:

More than likely if the magnetic sound works so does the optical. Ask John Capazzo he has one.

PatD

Posted by Hugh Thompson Scott (Member # 2922) on September 15, 2012, 01:21 PM:

Akshay,if you put a sliver of paper or a paintbrush in between
the receptor and the lens,you'll hear the noise it creates on the
speaker, which tells you that the optical sound works.

Posted by Akshay Nanjangud (Member # 2828) on September 15, 2012, 02:00 PM:

Thanks guys. Hugh, I did do what you said and I heard clicks when I slid paper. So, it seems fine.

Again, my other question was the magnetic sound coming down and engaging in O mode. Is this normal?

Posted by Winbert Hutahaean (Member # 58) on September 15, 2012, 02:07 PM:

Akhsay, if you want for a test purpose, I can send you a roll of optical print from a film made in 1985 for free as long as you pay for postage.

Email me for your address.

Posted by Akshay Nanjangud (Member # 2828) on September 15, 2012, 02:19 PM:

Thanks, Winbert. I sent you an e-mail.

Posted by Hugh Thompson Scott (Member # 2922) on September 15, 2012, 03:08 PM:

No Akshay,their should be no mag signal if you have it in Opt.
there could be a bad connection on your switch.I'm sure that
someone on here with more knowledge on electrics than myself
will be able to give some advice.

Posted by Rob Young. (Member # 131) on September 15, 2012, 03:36 PM:

I think Akshay means that in optical position the mag sound pressure guides still move down into place?

This is normal with the ST1200HD

You should see the first of the 2 lower rubber rollers slightly alter position when switching to optical (it moves back slightly).

Posted by Akshay Nanjangud (Member # 2828) on September 15, 2012, 04:59 PM:

Rob, what you understood is exactly what I meant. The rubber rollers do alter position like you say. Things look okay for now.

On a similar note, what do you all do with a new projector before running the more valuable films? Of course, the cleaning, lubricating drill is standard. After this I run the same 400' of film a few times, look to see if the film is developing scratches with more runs, see that the sound is satisfactory. If the projector passes these tests, I play my favorite films. Is this correct?

Posted by Andrew Woodcock (Member # 3260) on September 15, 2012, 07:10 PM:

All magnetic sound head assembly still engages the film path fully on all Elmo projectors when playing back Optical sound films. The switch is obviously moved from mag to opt but without the Mag sound heads engaged the optical soundtrack will sound poor ie main switch position 1. This is due to the effect the rollers have on smothing the films path as they pass through either of the sound heads or the Silicon Photo Diode.Hope this helps

Posted by Akshay Nanjangud (Member # 2828) on September 15, 2012, 07:41 PM:

Thanks, Andrew. Once Rob said the pressure guides (now that I know what to call it) do engage I had an inkling the reason would be what you gave. Now that am sure the pressure guides do move down, I feel better.

Posted by Rob Young. (Member # 131) on September 16, 2012, 05:43 AM:

Just to be technically accurate, it's the "Head Pressure Assembly" which moves down into place! [Smile]

Akshay, I think that sounds like as good a plan as any to test an unknown projector; I always check the film path before and after every reel, maybe giving it a blast with compressed air just to be sure it is clean.

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