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Author Topic: Chinon 7500 Sound Fault
Simon McConway
Phenomenal Film Handler

Posts: 1085
From: Doncaster, UK
Registered: Jun 2004


 - posted November 17, 2014 11:51 AM      Profile for Simon McConway   Email Simon McConway   Send New Private Message       Edit/Delete Post 
Can anyone suggest how to cure the sound going muffled, then clear, then muffled and so on throughout projecting literally any film on this machine please? It's literally one second of clear sound, followed by one second of muffled sound in an on-going way throughout!

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Maurice Leakey
Film God

Posts: 5895
From: Bristol. United Kingdom
Registered: Oct 2007


 - posted November 17, 2014 02:51 PM      Profile for Maurice Leakey   Email Maurice Leakey   Send New Private Message       Edit/Delete Post 
Flywheel touching something as it rotates?

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Maurice

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Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012


 - posted November 17, 2014 02:59 PM      Profile for Andrew Woodcock         Edit/Delete Post 
Sounds like a tracking issue as the mag stripe passes the head as though you hace intermittant misalignment from a worn capstan roller or guide perhaps or worn pressure pads underneath the head maybe.

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"C'mon Baggy..Get with the beat"

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Simon McConway
Phenomenal Film Handler

Posts: 1085
From: Doncaster, UK
Registered: Jun 2004


 - posted November 17, 2014 03:39 PM      Profile for Simon McConway   Email Simon McConway   Send New Private Message       Edit/Delete Post 
Thanks gents. Have checked flywheel. This is free to turn. What next?

Sound head access is very very tight!

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Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012


 - posted November 17, 2014 03:49 PM      Profile for Andrew Woodcock         Edit/Delete Post 
Does the film show any signs of lateral movement on entering or exiting the sound head section? For that matter even unusual vertical movement around the lower loop before entering the sound head section?

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"C'mon Baggy..Get with the beat"

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Simon McConway
Phenomenal Film Handler

Posts: 1085
From: Doncaster, UK
Registered: Jun 2004


 - posted November 17, 2014 04:06 PM      Profile for Simon McConway   Email Simon McConway   Send New Private Message       Edit/Delete Post 
No, film enters sound head normally. Even pushing the pressure plate up by hand makes no difference.

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Rob Young.
Phenomenal Film Handler

Posts: 1633
From: Cheshire, U.K.
Registered: Dec 2003


 - posted November 17, 2014 04:16 PM      Profile for Rob Young.     Send New Private Message       Edit/Delete Post 
Simon, this could be a common sound head pressure issue.

I know this sounds odd, but what print are you running?

Andrew is correct in checking sound head pressure, but also check print width over the sound head.

Poly prints from Marketing just hated Chinons!

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Simon McConway
Phenomenal Film Handler

Posts: 1085
From: Doncaster, UK
Registered: Jun 2004


 - posted November 17, 2014 04:27 PM      Profile for Simon McConway   Email Simon McConway   Send New Private Message       Edit/Delete Post 
Have got clear sound if I pull, by hand, the lower plate on the sound head, which pushes the film up, towards myself. Must be alignment then? I will try some other prints.

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Brad Kimball
Phenomenal Film Handler

Posts: 1171
From: Highland Mills, NY USA
Registered: Jun 2003


 - posted November 18, 2014 07:08 AM      Profile for Brad Kimball   Email Brad Kimball   Send New Private Message       Edit/Delete Post 
Could it be that the heads are just worn? Don't sound heads have a life span of a certain amount of hours before they're no good anymore?

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Simon McConway
Phenomenal Film Handler

Posts: 1085
From: Doncaster, UK
Registered: Jun 2004


 - posted November 18, 2014 10:40 AM      Profile for Simon McConway   Email Simon McConway   Send New Private Message       Edit/Delete Post 
Sounds heads are fine because I can get perfect sound when that lower plate is pulled forward.

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