This is topic Chinon 7500 Sound Fault in forum 8mm Forum at 8mm Forum.
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Posted by Simon McConway (Member # 219) on November 17, 2014, 11:51 AM:
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!
Posted by Maurice Leakey (Member # 916) on November 17, 2014, 02:51 PM:
Flywheel touching something as it rotates?
Posted by Andrew Woodcock (Member # 3260) on November 17, 2014, 02:59 PM:
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.
Posted by Simon McConway (Member # 219) on November 17, 2014, 03:39 PM:
Thanks gents. Have checked flywheel. This is free to turn. What next?
Sound head access is very very tight!
Posted by Andrew Woodcock (Member # 3260) on November 17, 2014, 03:49 PM:
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?
Posted by Simon McConway (Member # 219) on November 17, 2014, 04:06 PM:
No, film enters sound head normally. Even pushing the pressure plate up by hand makes no difference.
Posted by Rob Young. (Member # 131) on November 17, 2014, 04:16 PM:
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!
Posted by Simon McConway (Member # 219) on November 17, 2014, 04:27 PM:
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.
Posted by Brad Kimball (Member # 5) on November 18, 2014, 07:08 AM:
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?
Posted by Simon McConway (Member # 219) on November 18, 2014, 10:40 AM:
Sounds heads are fine because I can get perfect sound when that lower plate is pulled forward.
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