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Topic: Elmo 800 GS - No sound from Track 2
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Robert Crook
Junior
Posts: 8
From: Cumbria, UK
Registered: Oct 2018
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posted October 16, 2018 04:13 AM
Thank you Steve for that response
Yes it is a stereo print.
I have tried all the switches, to no avail.
I have fed the sound from the speaker sockets ( 2 pin) into my amplifier and the sound is coming though just one speaker
I have just now played the sound through the speaker jack, with the same result.
Also directly though some Bose headphones, and it is the same, through one speaker.
Could it be the sound heads?
One thing I have noticed, when I turn the volume up on track 2 I have the hissing sound, but also a frequent and rapid ticking sound.
Thanks again Steve, I really appreciate your help here.
Regards
Robert
Rob, just saw your post. Im using a Gremlins print, i have also tried with several other examples with the same result.
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Steve Klare
Film Guy
Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003
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posted October 16, 2018 07:59 AM
This is one of those that could be a lot of things.
It could be the heads, but typically not. I hate to say "never" because words like "never" and "always" were just invented to make people look foolish later on.
People on this forum have had some success going over their sound boards looking for cold solder joints and reflowing them with new solder: could be.
I had a similar adventure with my ST-1200HD about a year ago. Track one was OK, track two was dead, and fairly often the sound would break into to an oscillation. I think I remember some ticking as well.
I managed to get a schematic (which is like finding gold) and I checked it out. On this machine you have a pre-amp stage for each track. These are buffered out to the two unamplified outputs, which are what you amplify on an ST-1200HD to get stereo. These two signals are also summed together and fed into a power amp stage, which drives the internal speaker and the external speaker jack. This is also divided down trough a resistive divider to become the monaural Aux.
I don't have a lot of test equipment at the house, and I don't want to explain troubleshooting a movie projector at work, so I needed a guess: something as easy and cheap as possible, but still very plausible. I needed something if I was wrong I hadn't committed myself too deep.
The preamp stages are built around a 7 pin preamp IC. The power stages are built around this immense power amp IC. They are both obsolete, but still pretty findable.
The ST-1200HD is a twin track monaural machine: it has one power amp IC. The GS-800 is true stereo: you probably have two.
My best guess was the preamp IC for track two had gone bad, since track one still worked and the sound came up to full volume.
The preamp ICs were like 5 bucks a pop on E-bay, and not too bad to replace. There are four of them on the board, so I decided to replace them all.
I'm a pretty decent solderer, and I probably could have pulled it off at home with what I have to work with there, but I have a good friend at work that has ninja-level soldering training and works at an industrial quality soldering station, so I chickened out and asked a favor.
Since I'd guessed, I wasn't sure if it would pay off, but it works fine now.
If you're up for it, and nothing else helps, I can provide you information on how to do it. Elmo used these same ICs on multiple models. (If we can dig up a GS-800 schematic, so much the better.)
Other than that it could come down to replacing the sound board as a unit.
--------------------
All I ask is a wide screen and a projector to light her by...
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Robert Crook
Junior
Posts: 8
From: Cumbria, UK
Registered: Oct 2018
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posted October 24, 2018 01:03 PM
Gave the whole thing a good workout, cleaning, tweaking, lubricating, plugging unplugging, learning a great deal in the process, and guess what, track 2 is alive, and sounding gooooooood.
So thanks, that was a lot of fun.
No idea what specifically fixed it, but that was half the fun.
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