8mm Forum: Newby mamber just starting out..

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Posted by Nick Field (Member # 2132) on July 26, 2010, 01:20 AM:

Hi people,I've just started out in the world of real film on super 8 format.I have two elmo projectors in my grasp, one is the elmo st600m and an st800 magnetic which I'm currently trying
to repair it's sound problem at the moment. As I have only started out collecting films i have only a some 400 footers to start with and an odd 600.
The films i have so far are as follows.
How the west was won 400ft
Earthquake 400ft starting to fade.
Reach for the sky odd reel on 400ft reel 4.
Who framed roger rabbit odd reel on 600ft reel 2.
I also have some old family footage that was taken in the 70's
which bought back lots of memories for me as a child.
Anyway sorry to bore you all with my intro I look forward
to speaking to you all on other subjects.
Regards.
Nick.

Posted by Dan Lail (Member # 18) on July 26, 2010, 01:58 AM:

Hi, Nick,

Welcome to the forum. You're not boring at all. The ST-600 and ST-800 are great machines. Could you provide more details of the problems you are having with them. I am sure some one here can help.

Posted by Joe Taffis (Member # 4) on July 26, 2010, 05:03 PM:

Hi Nick, and welcome! As Dan said, state your problem with your ST800 and maybe someone can help. Lots of info on ELMOs as well as other projectors to be found here; both through using the search feature for Forum archive info, or just asking for help with a new problem [Smile]

Posted by Nick Field (Member # 2132) on July 27, 2010, 02:03 AM:

Hi Dan/Joe thank you for your warm welcome, The problem really is with the 800.I'm currently investigating a no sound problem with the machine,I've only got as far as testing the ohms of the sound heads which read about 6-8ohms from both which I did'nt think was far away. Anyway when switching on the amp I can hear the pop as it comes into life and a very very faint hum which I think is natural output from the amp.When running film through the projector I've turned up the volume but no sound at all,the VU meter does not move a mm. I've tried the record button trick but without luck as I do a bit of mobile djing I have plugged the aux out & headphones into my mixer and still no sound. I think the next thing to check will be the volume control values with the volt meter.
If I plug a mic into the mic input should I hear my voice through the speaker when recording?
I don't think it's an amp problem as I can hear the hum from the speaker so it's got to be within the volume section of the system. As I turn up the volume there is no increase in hiss or noise ratio at the speaker.
I will strip the projector down further and give you an update on my progress and maybe take some shots for you to see.
Any suggestions I could try would be a great help and thank you for your interest. [Smile]

Nick.

Posted by Martin Jones (Member # 1163) on July 27, 2010, 02:44 AM:

One word of caution when "I strip the machine down further", especially with regard to sound. There is mechanical interlocking involved that must be correctly engaged on re-assembly... or you could be in real trouble.
There are many tests you can do on this machine without "stripping down". I have one of these machines (ST600 version) that I have converted for stereo, and know the sound section intimately. You can contact me if you wish for guidance on blagdonian(at)btinternet(dot)com, but contact me before Thursday as after that I will be missing for a few days having my left knee exchanged for a new one.

Posted by Steve Klare (Member # 12) on July 27, 2010, 04:27 AM:

Hey Nick,

Try all the jacks, too. They have bypass contacts that can oxidize.

Something to look for is there is this tiny circuit board in back of the framing knob where wires come from the heads and then go out to the sound board. The wires are soldered to the surface of the board and I've seen the bonds break and the connection go open circuit.

An easy test you can try to see if your heads are getting through to the amp is turn the volume up enough to hear hum, and then move a small piece of metal (a ring will do it) near and listen for a change in the hum due to the magnetic field distorting. No change: no heads.

Sometimes a mechanical problem can cause no sound. There is a chute that presses the film down on the heads when the projector is going forward with the lamp lit. I've seen this get hung up because of problems in the linkages and not press the sound stripe down on the heads. Even with a perfectly functional sound circuit you can hear absolutely nothing but hum. You can tell it's happening because the film won't be pressed down on the pinch roller and the flywheel won't turn. You can look down through the cooling vents next to the handle and see the flywheel turning. It should be doing something like two or three turns per second at 24 FPS.

Just for laughs, make sure the speaker was re-plugged in to the sound circuit the least time the back cover was removed. (This one gets us all eventually.)

I've brought my ST-800 back from either death or silence a few times.

Best of luck with your knee, Martin. The Physical Therapy is a battle but fighting it makes all the difference.

Posted by Nick Field (Member # 2132) on July 27, 2010, 04:33 PM:

Hi thank's Martin & Steve for your advice,strip down will be the last resort ,the film is being pressed quite firmly against the heads and the big fly wheel rotates as the film is being passed,the speaker and amp seem to be ok as when I turn on the amp by the volume knob it first pops and the vu needle fluctuates for a split second. I have tried the volume at full but there is no difference in hum or hiss.I will try the small circuit board for dry cracked joints. I'm just wondering if the main sound board has gone up the creek. [Roll Eyes]

Posted by Steve Klare (Member # 12) on July 27, 2010, 05:34 PM:

That is troubling,

One of these machines in healthy condition will send a lot of hum and hiss through the speaker when the volume is turned up full, more than enough to make you want to turn it back down.

That kind of silence could be something fundamental like the DC supply voltage to the sound board collapsing when you turn the sound on.

-Just enough energy to give you that pop through the speaker and then nothing left to power the circuit.

It would be interesting if you could measure the supply voltage at the board before and after you turn on the sound and watch what it does.

Posted by Nick Field (Member # 2132) on July 28, 2010, 12:56 AM:

Ok thanks Steve, I'll test the voltage and let you know how I get on. [Smile]

Many thanks.
Nick.

Posted by Nick Field (Member # 2132) on October 22, 2010, 01:54 AM:

Right I have tested the connecting pins into the board I have two pins which fluctuates between 3.5-5v and one pin with 35v, and one pin with 0v,the other pins I think are output sound.Does anybody know If when the main switch is turned to lamp illumination the amp output is switched on like the gs 600?
If so where does the supply come from?

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