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» Film-Tech Forum   » Operations   » Film Handlers' Forum   » SRA-5 Schematic/Help Needed - No sound

   
Author Topic: SRA-5 Schematic/Help Needed - No sound
Matt Close
Expert Film Handler

Posts: 226
From: Hervey Bay, QLD, Australia
Registered: Sep 2001


 - posted 08-24-2004 07:15 PM      Profile for Matt Close   Author's Homepage   Email Matt Close   Send New Private Message       Edit/Delete Post 
Does anybody have a schematic or technical info on the Dolby SRA-5? Mine blew a fuse and now doesn't pass through any sound! [Eek!]

Any help and advice is welcome too! [Big Grin]

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Daryl C. W. O'Shea
Film God

Posts: 3977
From: Midland Ontario Canada (where Panavision & IMAX lenses come from)
Registered: Jun 2002


 - posted 08-24-2004 07:44 PM      Profile for Daryl C. W. O'Shea   Author's Homepage   Email Daryl C. W. O'Shea   Send New Private Message       Edit/Delete Post 
Replace the fuse. [Big Grin]

Actually, there is some documentation in the manuals section. Not sure what it is, I don't have time to download it on dialup here.

SRA-5 and the SA-5.

edit: thought I had pasted in two SRA-5 links, not one for the SA-5

[ 08-24-2004, 09:13 PM: Message edited by: Daryl C. W. O'Shea ]

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12122
From: Annapolis, MD
Registered: Dec 1999


 - posted 08-24-2004 08:23 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
The SA-5 is a CP-100 stereo surround adapter...

The SRA-5 was made during Dolby's dark years on documentation...it and the Cat 113C were done around the same time. There is virtually no doucmentation on the schematics of the unit that I am aware of (though there must be some, I don't think they have ever made it to any sort of publication).

Change the fuse and in the mean time wire around the SRA-5. In a CP-200 type installation, the sound must pass through the SRA-5 and it will indeed nix the sound. It is good to have a bypass fanning strip handy just in case.

Steve

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Matt Close
Expert Film Handler

Posts: 226
From: Hervey Bay, QLD, Australia
Registered: Sep 2001


 - posted 08-24-2004 09:06 PM      Profile for Matt Close   Author's Homepage   Email Matt Close   Send New Private Message       Edit/Delete Post 
I was actually using it with a JS-200 Ultra-Stereo processor. What a huge difference it makes over the USL SR card!!!!

Anyhow, I have now discovered that if you power down the SRA-5, you here the sound that has been passed through the cards for a split second until the caps discharge...... I know it is the processed sound I am hearing because you can't hear it if the cards aren't in. So, I guess I am looking at a control/logic problem. I see there is a CD4052 chip in there for signal switching, but I don't know what goes where, or what rails should have what on them to trigger what!?!? [Roll Eyes] ... if you get the drift..... so I am hoping someone either has schematics or has struck the problem before..... Even the pinouts for the CAT280T cards would help, so I could see where the signal is making it to before it is interrupted.

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Matt Close
Expert Film Handler

Posts: 226
From: Hervey Bay, QLD, Australia
Registered: Sep 2001


 - posted 08-25-2004 12:36 AM      Profile for Matt Close   Author's Homepage   Email Matt Close   Send New Private Message       Edit/Delete Post 
Don't worry ... Found the problem holding the 'inhibit' leg high on the CD4052. All good now.

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