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Topic: Elmo GS 1200 Pulse Sync Pulse Level Jumping Needle
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Evan Samaras
Jedi Master Film Handler
Posts: 513
From: Queens, NY, USA
Registered: Oct 2015
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posted April 30, 2017 07:52 PM
Hello all!
Thanks to a forum member I was fortunate enough to bring home a GS 1200 today!
The unit was tested with a Pedro box and I witnessed the Pulse Sync and Levels working normally. Now onto my issue....
I created a Din connector that allows my PC to output the pulse sync. I was provided with an audio file by a forum member, and have created a few 23.976hz files myself. However, my Pulse Level is behaving oddly.
At first it appears there is no response from the Pulse Level. However, i start to raise the output, and when it reaches a certain level the Pulse Level starts to read.... but the readings are jumping from Extreme left to Extreme right, back and forth quickly.
I'm hoping someone may have ideas for troubleshooting, or perhaps even the answer! My project setup is 44,100, 24bit, and the audio file is a square signal at 23.976hz. Any ideas? Thanks!
-------------------- ...When there's no more room in hell, the dead will walk the Earth...
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Paul Browning
Phenomenal Film Handler
Posts: 1006
From: West Midlands United Kingdom
Registered: Aug 2011
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posted April 30, 2017 08:40 PM
Hello Evan, I have tried this with audacity but creating it has an mp3 file, then playing it through virtual dj to output it through the headphone socket, this worked fine. It could be that the computer is not high enough on the line output to drive this pulse circuit, it has to be at least .775mv line level or more, like that of a cd player, can you burn your pulses to a recordable cd and then put that through the pulse sync via a cd player, this may tell you if its a level problem. They do have a known capacitor fault in the circuit which cause's a similar problem, where the cap has dried out from lack of use, but you have seen this working via the pedro box, but its worth mentioning it.
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Evan Samaras
Jedi Master Film Handler
Posts: 513
From: Queens, NY, USA
Registered: Oct 2015
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posted May 01, 2017 12:08 PM
Good advice Paul. Tested, and the connections are indeed continuous, no shorts. At least I now know my cable connection were successful. I've also tested numerous 23.967hz signals, some sent to me by those who have had success, so I can rule out the audio from the contributing issue. I've used both the soundcard from my Mac Mini as well as the external UR28M and the issue was the same. It's as if there is no singal, and once I reach a a specific volume level it begins to jump, even with the pule level being at the lowest setting
I'm at a loss for ideas. Might anyone have an idea what else might cause the needle to jump?
-------------------- ...When there's no more room in hell, the dead will walk the Earth...
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Paul Browning
Phenomenal Film Handler
Posts: 1006
From: West Midlands United Kingdom
Registered: Aug 2011
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posted May 01, 2017 02:56 PM
Evan I assume you are going to do some pulse sync recording, just make sure you can do so, if you have a projector that's not been used for recording just play back, you may find the cap will not be any use, and produce poor recording quality, another known problem with the Elmo GS, not impossible to repair but you need some skill in the soldering department, difficult to remove the old stuff and replace. Are you using the original laptop power supply ?. The reason I ask this is because if you have a replacement power supply you can get mains noise being picked up by the sound card, believe me when amplified this presents itself as mains buzzing, very similar to your pulse sound. Try it without the power supply plugged in, and try to get your pulse sync in through the input of the Elmo, so you can monitor it as it comes in, auxiliary input to on the Elmo is a 3.5mm socket, out is an headphone 1/4 jack. If you listen to the incoming sound you may hear if its a clean signal with no background interference.
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Evan Samaras
Jedi Master Film Handler
Posts: 513
From: Queens, NY, USA
Registered: Oct 2015
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posted May 24, 2017 01:41 PM
I want to thank everyone who has helped me so far
And now with an update!
I learned that my ESS Board was actually of the earlier series and only allowed Sync up to 18 fps. However, I was provided with information that allowed me to make a modification to my board to allow syncing above 25fps.
Now my issues...
at 23.976hz the needle sits just below the center, touching blue. When I change the signal to 25hz, it sits perfectly in the middle! No matter what signal I send I have to turn the pulse level to max to stabilize it. My GS-1200 says 50hz & 60hz. Could it possible be running 50hz somehow?
It does not appear to have variable voltage. It is set for 125v. Also, as of recently, the bulbs begin to blow very fast. The first time this occurred was when turning the bulb to the brightest setting. Two bulbs blew out immediately since then (at normal lighting), and a third blew after approximately 200'
Any thoughts and suggestions would be greatly appreciated!
-------------------- ...When there's no more room in hell, the dead will walk the Earth...
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