8mm Forum: No sound from our Elmo ST-1200

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Posted by Ron Douglas (Member # 2990) on February 02, 2013, 03:00 PM:

I wonder if anyone can help with this unusual problem?
A couple of weeks ago, we projected 3 x 800' reels back to back, beautiful sound and picture, then part of a 400' before the bulb blew. Got a spare and hooked it up for the start of a show tonight. Lovely picture, but no sound.
Unless I am mistaken, I don't think there is a switch I could have accidentally moved that has muted the sound, as all I did was change the bulb. There is still life to the speaker
(loudening hum when turned full up, some gentle crackle), but neither magnetic or optical tracks, on films known to have good sound, will perform. Surely I must have made an elementary mistake, or is it possible the sound head has simply given up the ghost? Thanks for any help you can offer [Smile]

JUST REALISED IT WILL PROBABLY BE A 3AMP FUSE...HOPEFULLY!!

Posted by John Capazzo (Member # 157) on February 02, 2013, 03:58 PM:

Ron,

Did you try other prints? Perhaps you have a print that may have been stripped (near magnetic fields)? Changing the lamp has no effect on the sound. The sound head is fine. They don't just burn out. When you first loaded the film and depressed the threader (green), did it release on it's own? If not, you'd have to manually depress the thread release lever (black; just below the take up reel). Another thing may be the record button didn't retract 100%. You may have pushed that in by mistake.

Posted by Ron Douglas (Member # 2990) on February 02, 2013, 04:21 PM:

Thanks John, good advice indeed, but all those things had already been checked, including other sound films.
I've now replaced the 2 x 3amp fuses for the amplifier and the exciter lamp. The exciter lamp fuse had blown, and now lights when the sound switch is changed from magnetic to optical.
Odd thing is that there is still no sound, and the case speaker is definitely attached as I can hear the increase in hum volume as the sound knob is switched on and turned to full, then back to low, then off...your continued thoughts are very welcome.
Had a little peep at the repair manual and it mentions Midget fuse 2A for AMP input, but I simply can't locate that on the diagrams to attempt to replace it.

Posted by Steve Klare (Member # 12) on February 02, 2013, 04:59 PM:

Sometimes you get oxide buildup on switches which will prevent audio signals from getting through. This is because the low voltage switches that are oxide immune cost a ton (gold plated contacts) so Elmo stuck with the regular ones which need high voltage to break the oxide films. Fortunately giving the switches some excersize usually works too.

Find every switch associated with sound you can and move it in and out of its normal position (...and then back to normal) about 10 times. Then maybe your sound will come back.

The red recording switch is my usual suspect.

-so much that I soldered a short across mine! (Life made simpler, one step at a time...)

Posted by Ron Douglas (Member # 2990) on February 02, 2013, 05:05 PM:

Many thanks Steve, that sounds great...free beer (via Paypal!) for the answer that solves the problem...and that's a promise!! [Wink]

Now to get switching!!

WOW!!!!!!!!!
That's the sound back!!!!!
Thanks so much John and Steve.
PM me your paypal email and i will sort you out with a light refreshment...we are delighted, that's just so cool, I can't tell you! It's kinda late, so a change of film should be good...original King Kong to take us in to the wee hours!
Bless you both guys, seriously!

Posted by Steve Klare (Member # 12) on February 02, 2013, 05:47 PM:

Glad to help, Ron!

I enjoy fixing projectors: doubly so when I don't need to do any work!

John and I will both be at Cinesea in April.

If you send Paypal for a beer each we will have them there and post a picture in this thread.

Deal, John?

(Anybody who would like to watch us drink the beer should attend!)

(You should attend even if you don't!)

Posted by Ron Douglas (Member # 2990) on February 02, 2013, 06:08 PM:

That sounds fine Steve, let me know your details and i will have that arranged, damn, it sounds like it could be a great time, shame it's over the pond...meantime, the audience need the reel changed!
PM me...cheers!

Posted by John Capazzo (Member # 157) on February 03, 2013, 06:47 AM:

Ron,

Glad we could be of help.

Steve gets two free beers since I don't have a taste for beer.

Steve, I may not be there this April. Where my table is, you may a pic of an espresso machine as a remembrance; or an empty 800' Bonum case.

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