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» 8mm Forum   » 8mm Forum   » Could use some help diagnosing a Sankyo soundhead.

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Author Topic: Could use some help diagnosing a Sankyo soundhead.
David Unruh
Junior
Posts: 7
From: Woonsocket, RI, USA
Registered: Apr 2019


 - posted May 12, 2019 05:47 PM      Profile for David Unruh     Send New Private Message       Edit/Delete Post 
Been having sound problems with my Sankyo 702 for a while. The sound only works when the projector has been warmed up by the bulb for several minutes. I thought the problem was in the amp itself but I made an adapter to plug into the board where the sound head normally plugs in and hooked a mic up to it. I can talk into the mic and sound comes out of the speaker. So I guess the problem is in the soundhead? Tried a multimeter between the red and white wire on each side. got nothing. But I do get resistance between red and white wire on erasing part of the head. Is it typical for the soundhead to go bad on these Sankyo's since it's so close to the bulb? How do I get the head apart? Looks like it's just 2 screws to get it off the projector right?

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Brian Fretwell
Phenomenal Film Handler

Posts: 1785
From: London, UK
Registered: Jun 2014


 - posted May 12, 2019 06:04 PM      Profile for Brian Fretwell   Email Brian Fretwell   Send New Private Message       Edit/Delete Post 
It sounds to me more like there could be a high resistance on the connection of the wires to the sound head, or even the join breaking but re-connecting when the solder has expanded due to the heat of the lamp. I would try re-soldering before taking the head off.

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David Unruh
Junior
Posts: 7
From: Woonsocket, RI, USA
Registered: Apr 2019


 - posted May 12, 2019 06:47 PM      Profile for David Unruh     Send New Private Message       Edit/Delete Post 
Yeah, I thought there might be resistance at the connections of the plug to the top of soundhead too. But I checked each line from the plug to top of sound head. No resistance on any. So maybe I could try resoldering the leads on the top to be sure it's not a bad solder joint. I'm afraid I might have to take it apart though.

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Maurizio Di Cintio
Jedi Master Film Handler

Posts: 977
From: Ortona, Italy
Registered: Jan 2004


 - posted May 13, 2019 10:39 AM      Profile for Maurizio Di Cintio   Email Maurizio Di Cintio   Send New Private Message       Edit/Delete Post 
These heads are very resilient, almost on par with Elmo's heads. So the heat from the lamp is not an issue.

--------------------
Maurizio

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David Unruh
Junior
Posts: 7
From: Woonsocket, RI, USA
Registered: Apr 2019


 - posted May 13, 2019 03:07 PM      Profile for David Unruh     Send New Private Message       Edit/Delete Post 
Maybe, I'm not getting any reading from either side of head with my ohm meter though. The bulb is 150 watts and very close to the head. When I check the erase head it reads 2.6 on both sides and it is slightly more protected from the bulb. I'm wondering if I can dig through the epoxy to find the problem now? My next question was going to be if I can use the head from an Elmo and if the head from a sound camera and projector would be the same?

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Nantawat Kittiwarakul
Master Film Handler

Posts: 280
From: Rajburana, Bangkok, Thailand
Registered: Aug 2017


 - posted May 13, 2019 11:15 PM      Profile for Nantawat Kittiwarakul   Email Nantawat Kittiwarakul   Send New Private Message       Edit/Delete Post 
Or try tapping the signal directly from the head&feeding it to the external preamp? Done similar to this on my 16mm projector,feeding it into external preamp's microphone input. Works for me. This will immediately prove that the head is still working or not.

--------------------
Just a lone collector from a faraway land...

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