8mm Forum: Elmo GS 1200 Pulse Sync Pulse Level Jumping Needle

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Posted by Evan Samaras (Member # 5070) on 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!

Posted by Paul Browning (Member # 2715) on 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.

Posted by Evan Samaras (Member # 5070) on April 30, 2017, 09:18 PM:

Hey Paul, thank you for the response. I'm running an external soundcard that I use for vocal recording and music engineering (Yamaha UR28m) the max output I believe is 16dbu, which should be more than enough output level if I'm not mistaken. I'll double check my settings.

If the signal was too low wouldn't the pulse level just stay put at the left/Red end? Mine is bouncing quickly left to right. Makes me think as if the signal comes in strong and drops just as fast, continuously. As I raise the volume it goes from no movement, to the fast bouncing movement I described. There doesn't seem to be anything in between.

I saw the pulse work yesterday, so I'm assuming I must have something wrong in my settings.

Posted by Mark Mander (Member # 340) on May 01, 2017, 04:32 AM:

I don't use a computer set up for my recordings and am using Region 2 25fps dvd's here in the UK but it may help, make sure the pulse sync needle is in the middle of the small meter when you start, on my GS if it isn't then the needle moves from side to side, Mark

Posted by Paul Browning (Member # 2715) on May 01, 2017, 06:26 AM:

I have had the same problem with a mk3, I tried a couple of times and it was doing the same Evan, but I tried it again the next day, it was fine with the needle staying stable in the centre portion of the meter. Are your din connections into the Elmo on the correct pins, just need a mono set of cables, one signal and one earth. It is a square wave going in, but very different coming out.

Posted by Evan Samaras (Member # 5070) on May 01, 2017, 10:01 AM:

I checked the diagram on an older post multiple times to ensure the connections are correct. I'm thinking of taking the DIN to Mono cable connector apart and resoldering it. Would a poor connection with sync, or ground cause the needle to jump? My outputs are 1/4" jacks, and it seems everyone is using 1/8", but I don't think that should make anything any different...

Posted by Paul Browning (Member # 2715) on May 01, 2017, 10:15 AM:

Only if the connections are shorted at either end Evan, use a multi meter set to diode symbol and check that the cables used are continuous on both and not shorted to each other before you unsolder them.

Posted by Evan Samaras (Member # 5070) on 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?

Posted by Paul Browning (Member # 2715) on May 01, 2017, 12:21 PM:

Are you using the usb port Evan, or an external sound card phono out, either way this needs to be mono into the pulse sync, I'm thinking your signal is coming out in stereo, unless you have configured the sound card to out put mono, these have left and right channels.

Posted by Evan Samaras (Member # 5070) on May 01, 2017, 12:55 PM:

I've tried on the Mac Mini out, but I have also tried on two external sound cards. The Yamaha UR28M and the Apogee Duet. They both use multiple line outputs in mono.

The signal is definitely coming out mono. The jacks/plugs/cables are all mono

Posted by Alexander Vandeputte (Member # 1803) on May 01, 2017, 01:03 PM:

Is your projector not in 'thread' modus ? My Elmo displays erratic behaviour when fed an ESS signal in thread modus. Once thread is released, than it behaves normal.

Posted by Evan Samaras (Member # 5070) on May 01, 2017, 01:15 PM:

Hey Alexander,

It is not in thread mode. I went ahead and put it into thread mode and re-released it in case something was stuck. Still the same behavior.

I made a test and generated a 4hz signal, and it appears the needle is jumping to the rhythm of the signal. It would appear its moving up and down with the oscillations (did I chose the right word?). Does this tell anyone something?

[ May 01, 2017, 02:16 PM: Message edited by: Evan Samaras ]

Posted by Paul Browning (Member # 2715) on 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.

Posted by Evan Samaras (Member # 5070) on May 01, 2017, 10:17 PM:

I'm sure I will opt for replacing the capacitor at some point. I would like to know I am able to Sync first. I have done some soldering, but I will take it one step at a time for now.

By laptop power supply do you mean my computer? My external soundcard has its own power supply. I did the test from my soundcard to the 3.5mm input. Without pulse sync, at full volume I am not hearing any noise/interference. The pulse sync sounds to come in as clean as I hear it on my near field studio monitor speakers.

Posted by Alan Rik (Member # 73) on May 02, 2017, 12:47 AM:

It could be the pulse sync module could need replacement. Mine worked fine one day than the next- it was doing what yours is. Couldn't stay steady. It happened to 2 of my GS 's in the past.

Posted by Gary Crawford (Member # 67) on May 02, 2017, 07:19 AM:

Don't know a thing about syncing......but the behavior you describe happens quite often in the analog audio world. You may have experienced it somewhere along the line. Sound levels erratic...then you boost them and they overmodulate. Many times it's not electronics...but corroded or dirty input or output jacks. Dirty or corroded plugs. And many times , dirty volume controls , or ESS switches. Something that simple can cause low signal or no signal...and then you boost it up and the signal arcs from plug to jack and suddenly you've got either too much signal...or just tiny arcs going on. AND computer jacks and connections are often not well made and fail often. they also get dirty.

Just a thought...not much of one, but a thought.
That GS is old and may have a lot of corrosion in controls and jacks. You never know.
It was great to see you in Cinesea. And I hope you get your problem resolved.
Like I said..I know nothing about the digital domain..

Posted by Paul Browning (Member # 2715) on May 02, 2017, 04:06 PM:

Good point Gary, certainly worth some switch cleaner on the ESS, switch and work it in, no harm in trying that, especially if its not been used to pulse sync before.

Posted by Evan Samaras (Member # 5070) on May 02, 2017, 10:03 PM:

Thanks Paul, Gary and Alan,

Was great to see you too!

Any suggestions regarding switch cleaner? Thanks again!

Posted by Paul Browning (Member # 2715) on May 03, 2017, 01:29 AM:

Servisol 10 is what I use, probably called something else in the us,

Posted by Bill Brandenstein (Member # 892) on May 03, 2017, 03:23 PM:

Evan, years ago I had occasion to try to get a GS to behave, and used some Caig Deoxit in the "+" and "-" speed buttons, as well as the other knobs in the Pulse Control area. But don't let this stuff near the lamp housing or anywhere else where high current occurs. And (with the projector off) work those buttons A LOT.

Having said that, you need to play with the GS's speed control knob and the level control knob. If they're not in agreement with what you're sending in, well then, bounceville. And they seem to affect one another a little bit.

So take heart. The first time I messed with one of these, I thought it was toast also. But eventually it tamed and worked like a champ.

Posted by Evan Samaras (Member # 5070) on May 04, 2017, 05:56 PM:

Thank you everyone!

I played around with some contact cleaner and especially on the ESS port. Unfortunately I'm not noticing any change. As I play with the pulse level knob there seems to be the slightest change, but still a lot of bouncing. It's as if there's no signal at all, and then as it crosses a specific level of volume it bounces a lot.

I guess I'll play around with it some more, maybe something will start to click at some point! However, I think I'll probably just have to give Leon a call soon and pick his brain, maybe buy an extra part.

Posted by Paul Browning (Member # 2715) on May 05, 2017, 01:17 AM:

There are two components to change Evan, the capacitor and a zener diode that cause these symptoms, do a search on here there is plenty of uploads to verify this from different source's, but they may not be the only cause's....

Posted by Evan Samaras (Member # 5070) on 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!

Posted by Evan Samaras (Member # 5070) on May 24, 2017, 05:47 PM:

So I took a reading from the lamp and I'm getting 27.6v on the lower setting and 31.4v on the brightest setting

Posted by Andrew Woodcock (Member # 3260) on May 24, 2017, 06:01 PM:

Way above what it ought to be Evan.
A fraction of a volt over 24vac max on high brightness really. That should be it.

If the projector is set at 125vac and you are supplying it close to this from a 60hz supply in your country, i dont know how these lamp holder readings are possible really???

Posted by Evan Samaras (Member # 5070) on May 24, 2017, 08:29 PM:

lamp voltage appears to be sorted! I was advised to move a wire on the transformer from P1 to P2. Thanks!

Now to see about the pulse sync, hmmm....

Posted by Evan Samaras (Member # 5070) on May 25, 2017, 12:14 AM:

In case it helps anyone (now or in the future) I found that by turning down the speed on my projector (while in ESS mode), the pulse level will fall in place when the signal is 23.976hz. It would not do so otherwise, only at 25hz. Even at max pulse level it was still short at 23.976hz.

Posted by Douglas Meltzer (Member # 28) on May 25, 2017, 09:52 AM:

Evan,

In that case, I would suggest a test record with ESS and playback in the normal setting to make sure it sounds fine without being controlled.

Doug

Posted by Evan Samaras (Member # 5070) on May 25, 2017, 10:45 AM:

Doug,

I can confirm that on playback it sounds fine

Posted by Douglas Meltzer (Member # 28) on May 25, 2017, 12:47 PM:

Great news! You are now on your way to obsessive re-recording....just like me.

Doug

Posted by Evan Samaras (Member # 5070) on May 25, 2017, 01:42 PM:

[Big Grin]

Indeed!

Posted by Bill Brandenstein (Member # 892) on May 25, 2017, 04:29 PM:

Congratulations, Evan!

So maybe we need to start a database of .wav-file masters we've created for re-recording. I know lots of times it's done on-the-fly directly from another media source. But if not, perhaps we should be sharing the wealth!

Posted by Evan Samaras (Member # 5070) on May 27, 2017, 11:33 AM:

Thank you Bill!

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