Film-Tech Forum ARCHIVE: Sub-woofer not working

This is topic Sub-woofer not working in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Ian Bailey (Member # 1752) on 11-10-2006, 07:14 PM:

Hi
While servicing this gear we realised that we had no Sub woofer activity.
Tested cabling from the output of the processor to the i/p of the amp and the o/p of the amp to the speaker-which tested fine.Swapped amps....same problem.
Processor is an early model Ultra-Stereo JS 105/195.
I swapped the Format card with an earlier type Format card(which was all I had to use) still no Sub.I'm not 100% sure if the earlier model Format card(out of a JS 5/95)is compatible with the 105/195.
Cheers Ian

Posted by Dominic Espinosa (Member # 2122) on 11-11-2006, 03:35 AM:

Assuming you're in analog could it be a failure of the SR card?

Posted by Ian Bailey (Member # 1752) on 11-11-2006, 05:23 AM:

Domonique that is right it is analogue.I just assumed the problem would be the Format card.I'll try swapping the other cards,but they are from an older model.
Cheers Ian

Posted by Gordon McLeod (Member # 33) on 11-11-2006, 01:40 PM:

I can't see how it could be the SR card since the USL original design sent a sum of the three stage outputs to the sub (handy for old mag films) If the unit has been upgraded to Digital check that a sub is present with digital
If you have the DTS switch relay in the sub line make sure it is wired correctly
If one inserts the Pink noise generator and you could see if there is noise on the sub output point

Posted by Dominic Espinosa (Member # 2122) on 11-13-2006, 02:33 AM:

Ah, Gordon.
I was under the impression the sub was contrived from the surrounds. My apologies.

Posted by Robert Throop (Member # 61) on 11-13-2006, 09:23 AM:

Are you sure that the voice coil isn't open?
Bob

Posted by Clint Koch (Member # 1179) on 11-13-2006, 11:59 AM:

Hello all,

Ian, the older JFM-05 is not really compatible with the newer JFM-10's and JFM-20's. The JFM-05 is a single card edge connection while the JFM-10 and JFM-20 are dual card edge.

On the JFM-10 that you have there is a relay for the sub channel that may be intermittent. I can send you the schematic if you like.

Clint

Posted by Ian Bailey (Member # 1752) on 11-14-2006, 09:51 PM:

Hi
Ok guys I've gotta admit I stuffed up!!
During the service of this gear I exchanged the power amps so had to replace the input plug to the Sub power amp.This was the first thing I checked when I realised I had no Sub BUT.....I just checked the continuity of the cable with a metre and I had reversed the wires when soldering onto the plug........it was 4:30 am so I can understand how my brain was working!!
Clint thanks for that information now I know what i can keep as spares out of the old 5/95.I would appreciate getting the schematic on the JFM-10 as we are a bit isolated(too many Dollars away from the nearest service tech!!)and any extra information we have helps heaps.
Cheers Ian