8mm Forum: GS-800 popping sound

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Topic: GS-800 popping sound

Vidar Olavesen
Film God

Posts: 2232
From: Sarpsborg, Norway
Registered: Nov 2012

posted April 23, 2013 01:51 PM

Anyone know what could cause this? At random intervals the speakers go popping. Quite annoying. Anyone have a clue?

Thanks

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003

posted April 23, 2013 06:31 PM

Sometimes it's electrostatic discharge between the film and the projector frame. This is usually worst in the winter because the air is dryer.

I have one film I have to keep away from my ST-1200HD because it pops like crazy, but any other film in that machine or that film in any other machine is just fine.

(I think maybe this film is acetate based and almost all the films I run through that machine are polyester based.)

Some sound tracks just come with their own clicks and pops. If it happens the exact same way every time you project the film, that's probably what you have.

--------------------
All I ask is a wide screen and a projector to light her by...

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Vidar Olavesen
Film God

Posts: 2232
From: Sarpsborg, Norway
Registered: Nov 2012

posted April 23, 2013 06:37 PM

Nope, it's not the film ... Works fine in the GS-1200. And it's random intervals, I think.

Needs grounding I heard someone say ... But I don't know where and how ... Anyone done it and can do a picture?

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Adam Deierling
Jedi Master Film Handler

Posts: 717
From: OH
Registered: Nov 2010

posted April 23, 2013 08:38 PM

When runnng a film that pops, try touching the last rear metal roller with your finger. Sounds odd but worked on mine. If the popping stops you can connect a short wire from that roller to the frame of the projector. Popping will stop. Hope this helps.

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Vidar Olavesen
Film God

Posts: 2232
From: Sarpsborg, Norway
Registered: Nov 2012

posted April 24, 2013 12:04 AM

Will check that today ... Thanks

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Ian O'Reilly
Jedi Master Film Handler

Posts: 737
From: London
Registered: Jun 2003

posted April 24, 2013 11:25 AM

Adams cure will work, I cured many GS800's this way.

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Hugh Thompson Scott
Film God

Posts: 3063
From: Gt. Clifton,Cumbria,England
Registered: Jan 2012

posted April 24, 2013 12:00 PM

I used to experience the same thing on the ST1200s when cleaning films mounted on metal spools,the spark could be seen discharging between spool and arm of projector, just static.

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Vidar Olavesen
Film God

Posts: 2232
From: Sarpsborg, Norway
Registered: Nov 2012

posted April 24, 2013 12:29 PM

Anyone have a picture of the solution?

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Adam Deierling
Jedi Master Film Handler

Posts: 717
From: OH
Registered: Nov 2010

posted April 24, 2013 12:59 PM

This is a picture I took a while ago enlarged to show the wire. I don't have this projector anymore otherwise Id open the door and take another picture for you to see where it attaches inside. But I'm sure you can find a screw to attach it to.

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Vidar Olavesen
Film God

Posts: 2232
From: Sarpsborg, Norway
Registered: Nov 2012

posted April 24, 2013 01:00 PM

Ah, okay, I thought it was the one inside the projector ... Thanks ... Will try to fix something to it and see :-)

Appreciate the picture

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Lee Mannering
Film God

Posts: 3216
From: The Projection Box
Registered: Nov 2006

posted April 25, 2013 07:15 AM

Done a few of these.

Remove front drop down cover
Remove green film guide which you will need to carefully un-screw along its rout.
Run a single strand of wire (I strip back a length of mains lead for this) and right along the back of the green film guide you need to have the wire make contact with each rollers screw that is screwed to the green guide.

I remove the large metal bracket at the top end of the green guide and start the wire behind it. Gradually work your way down and finally secure the wire along the back of the guide with insulation tape. If done neatly and right it works every time.

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James N. Savage 3
Phenomenal Film Handler

Posts: 1375
From: Washington, DC
Registered: Jul 2003

posted April 26, 2013 06:40 AM

My Sankyo ST-800 does this too, usually after 60 - 90 minutes of projecting. A single pop, every minute or so.

James.

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003

posted April 26, 2013 07:36 AM

I wonder if the real problem here is the film rubbing against that long plastic guide just before the exit and maybe against the flanges of the takeup reel: building up charge.

I went over the projection path of my ST-1200HD with an ohmeter, all of this is already metal and grounded to chassis:

-top sprocket
-gate and pressure plate
-sound heads
-bottom sprocket

There shouldn't be any buildup of charge in this part of the path, but then you have this long plastic guide with a plastic roller at the end, then you can throw in a plastic reel that may rub once a turn as a bonus.

-rubbing an insulator on an insulator (film on plastic) is a classic recipe for static electrictity.

It would be interesting to see the difference using a metal reel makes. I'm using an Elmo 1200 footer right now, I'll have to swap it with my old plastic reel and see.

--------------------
All I ask is a wide screen and a projector to light her by...

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Vidar Olavesen
Film God

Posts: 2232
From: Sarpsborg, Norway
Registered: Nov 2012

posted April 26, 2013 09:21 AM

I tried putting my finger on the roller where I was told to, no help. Seem to stop when I put my finger on the metal take up reel (metal ... maybe not so good?) and it didn't pop a single time on my 800' Smokey and the Bandit yesterday, but I put on a Donald Ducks Dilemma (I think this was the one I noticed on a couple of days ago too) it pops again ... Yeah, about every minute or so, but not like clockwork, sometimes earlier, sometimes later

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David Ollerearnshaw
Phenomenal Film Handler

Posts: 1373
From: Penistone Sheffield UK
Registered: Oct 2012

posted April 26, 2013 10:02 AM

Not sure if it applied to all ELMO ST/GS series projectors, when mine went back to C.Z. Scientific for a service. It had the same problem, they fitted a modification to it. Basically they fitted an earth to the flywheel, it cured the problem.

They told me due to the grease drying out that's what caused the static. Don't know if it was true, but like I say it cured it.

Try using a bit of wire and put one end on some bare metalwork on the casing and touch the other end lightly on the end off metal roller where the sound heads are.

The fix they did was inside though.

--------------------
I love the smell of film in the morning.

http://www.thereelimage.co.uk/

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003

posted April 26, 2013 10:24 AM

I think a plastic reel would be worse, especially if it rubbed on the film while it turned. The problem here is the metal reel is ungrounded, so it can't drain off the accumulated charge. All it would do is take the charge off the film and they'd accumaulate out on the outer circumference (-because they repel each other)

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All I ask is a wide screen and a projector to light her by...

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