8mm Forum: GS1200 sound issue

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Posted by Del Phillipson (Member # 513) on October 05, 2015, 02:33 PM:

Help needed if possible please. I am getting what sounds like someone doing a morse code message through my speakers on my GS1200, it does it whether I am watching a film or not, when I am watching a film it's not so loud but boy is it loud when I'm not watching one. It's only started doing it tonight, it does it twice then after about 10/15 seconds does it again, anybody got any clue's/idea's?. Help is always appreciated, Del.

Posted by Maurizio Di Cintio (Member # 144) on October 05, 2015, 03:44 PM:

If'it's occasional, it might be picking up the impulses of a GSM network: try keeping your mobile away from the projector.

Posted by Steve Klare (Member # 12) on October 05, 2015, 03:50 PM:

That's an interesting point. It doesn't have to be the machine.

I had all sorts of nasty stuff coming out of the audio on my machines once (two at the same time!).

-problem was the laptop plugged into the same outlet strip!

I also have to be careful with the ceiling light over the table. If it's all the way on or all the way off: no problem. Turn the dimmer partially down and the heads on the machines start picking up a buzzing interference.

First thing I try is making sure the lamp isn't dimmed.

Posted by Dominique De Bast (Member # 3798) on October 05, 2015, 04:01 PM:

I have some projectors that sometimes seem to be connected to a radio station or a taxi drivers frequence. The only way to stop the unwanted noises or voices is to switch the projector off. Those projectors, fortunately, don't always have the trouble. I talked about that with a repairman who said he had the same problem with one of his machine and there is nothing to do (anyway as far as he knows).

Posted by Paul Browning (Member # 2715) on October 05, 2015, 04:09 PM:

I get it with my gs if my mobile is about receive a text or ring, and taxi's driving past the house and using there radio or mobile in the cars. They do have a output amplifier fault common on this machine, but its a different noise completely to what you describe.

Posted by Bill Phelps (Member # 1431) on October 05, 2015, 04:20 PM:

I have an ST1200 and my cinema is in the basement and if the projector is on and setting idle or running the same noise will occur if I run the dryer or have my cell phone within 5' of the projector. I try to keep the projector off when doing laundry otherwise I get the interference.

Bill [Smile]

Posted by Alexander Vandeputte (Member # 1803) on October 05, 2015, 05:48 PM:

I had the same 'morse' code that turned out to be interference caused by a wifi transmitter that was too close to the projector...

Posted by Del Phillipson (Member # 513) on October 06, 2015, 03:32 AM:

Great views guy's, much appreciate the feedback, it's funny you should mention transmitters as I guy who lives around 50 meters away has the biggest CB ariel in the UK in his back garden it stands around 30/40 feet tall, it's huge, my wife asked this morning if I thought that could be the issue. Anyway I tried it again around 20 minutes after and it was ok no noise whatsoever, however it has happened before. Look's like the metal saw is coming out of the toolbox I have an ariel to cut down :-), thanks again guy's, Del.

Posted by Andrew Woodcock (Member # 3260) on October 06, 2015, 07:26 AM:

Sounds Just like the opening scene from poltergeist Del! Ha ha.

Remember,where rival neighbours were switching each other's tv channel over because of the size of the satellite dish in the middle of some important American Football game!

Go get your hacksaw Del! Nothing should come between a man and his film show lol [Big Grin]

Posted by Mathew James (Member # 4581) on October 06, 2015, 08:34 AM:

I saw this on Van Eck not long ago and remembered it when i read this thread:
http://shop.van-eck.net/EC-0010.html?_globalsearch=noise
Could this help this issue?
Cheers,
Matt

Posted by Rob Young. (Member # 131) on October 06, 2015, 09:11 AM:

I always found "dirty" mains noise a problem with my ST1200HD.

Especially when feeding an external amplifier as the output is so low.

Used to have an older cooker and when the thermostat kicked in, you'd hear a big pop through the speakers!!

Solution was to smooth the mains supply. I use a big 230v to 230v transformer that I acquired many years back; was being thrown out by a film production company. All the projection gear and amplifiers are run via that, so no more mains interference.

Probably not so safe or even legal these days for domestic use, but safe enough if you know what you're doing!! [Eek!]

Several mains smoothing units are available now for hi-fi / home cinema use, but the good ones aren't so cheap unfortunately.

Although this does sound more like radio or mobile phone signal interference.

Maybe a lead-lined room??
[Wink]

Posted by Del Phillipson (Member # 513) on October 06, 2015, 10:30 AM:

LOL Andrew, you should see the size of the aerial it's taller than his house and I totally agree Monday night is film show night and it was cut short, it has to go :-).
Thanks Matt, I've bookmarked the website and if it happens again I will seriously look into one of these, mind you we do have an independent electrical shop here and the guy sells everything, it's an Aladdins cave so would be surprised if he doesn't sell them.
Good shout Rob, a new mains cable is long overdue.
Some great feedback guys again many many thanks, Del.

Posted by Steve Klare (Member # 12) on October 06, 2015, 11:40 AM:

The thing I do to keep the line level outputs quiet is to make sure they are connected to chassis/earth/ground at only one end. If they are at both ends (especially if they are plugged in in different locations...) it means that part of the ground currents inside the house are also flowing in the shield of the line level connection and whatever nasty stuff is happening in them is in danger of becoming part of your audio.

Separating this from ground can be kind of a tall order: if you measure Ohms between the "cold" side of all of audio jacks and the third prong on the line cord of the projectors I mess with you will see a dead short. Operating a projector without the third prong (ground) is flirting with the possibility of getting a nasty shock (at least...) and something you shouldn't do. (The old ones with metal cases and two prong plugs worry me more than a little.)

On the other end, the shielded connection of the amp input is usually connected to chassis, and the whole thing can wind up grounded even if it has a two prong plug. Mine for example is connected through my TV and cable box to my service provider's ground, which is not even close to the same voltage as the ground in my outlets.

What I did about it is build an interface circuit to isolate ground at the projectors from ground at the amp. You don't need to do this to get the same result: there are various ground loop eliminators that are basically an audio quality transformer that couple one side to the other magnetically without any electrical connection between the projector and the amp. They aren't very expensive either.

You can plug everything into the same outlet too: at least now everybody is operating from the same ground and there is no voltage difference driving a noisy current through the projector/amp connection.

-this just wasn't practical for me. (...and I felt like building something!)

Posted by Steven J Kirk (Member # 1135) on October 06, 2015, 01:15 PM:

Don't want to be naughty but I'm sure Mr E had an electronic fix to this. Apparently the GS1200 Xenon was not bothered with this so it is a matter of fitting what was on that to the halogen model. Take a look on another forum. Fixes for both mains and RF interference. Sorry moderators but didn't want a fellow Elmo user to go without, I'll leave it like that...

Posted by Andrew Woodcock (Member # 3260) on October 06, 2015, 02:19 PM:

Well remembered Steven! I do remember reading about this modification now you reminded us all.

Surely anyone's and everyone's great work should be aired irrespective of any political reason for not doing if it's for the benefit of users.

Posted by Steven J Kirk (Member # 1135) on October 06, 2015, 02:39 PM:

I hope so. Don't want to make trouble. I just bumped up the two topics over there.

Posted by Steve Klare (Member # 12) on October 06, 2015, 02:39 PM:

The funny thing is I call "Mr. E" ("Mystery?!!") "Mr. F"!!!

Whether "E" or "F", he's still a friend.

Posted by Andrew Woodcock (Member # 3260) on October 06, 2015, 03:19 PM:

I think the E comes by way of his acronym Steve. [Big Grin]

Posted by Steve Klare (Member # 12) on October 06, 2015, 03:39 PM:

I got that...

(Isn't it really more of a pseudonym anyway?)

Posted by Andrew Woodcock (Member # 3260) on October 06, 2015, 04:47 PM:

True Steve.

Posted by Winbert Hutahaean (Member # 58) on October 06, 2015, 10:40 PM:

Did you hear "We come in peace" phrase...???

[Big Grin]

Posted by Del Phillipson (Member # 513) on October 07, 2015, 03:52 AM:

Just an update, tried it last night and low and behold it was fine, I got through 3 saw blades though :-), Del.

Posted by Andrew Woodcock (Member # 3260) on October 07, 2015, 04:08 AM:

Good work Del! Get another few hundred for all those mobile telephone masts that have sprouted just about everywhere!

Posted by Del Phillipson (Member # 513) on October 07, 2015, 04:20 AM:

Andrew, I'm thinking more of an acetylene burner :-)

Posted by Andrew Woodcock (Member # 3260) on October 07, 2015, 06:02 AM:

[Big Grin]

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