SC6000: 6dB loss between EDAC and Patchbay

Founded in 1973, Soundcraft first made its mark with the launch of the Series 1, the first mixing console in a flightcase.

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SC6000: 6dB loss between EDAC and Patchbay

Postby mokkinger » Mon Feb 24, 2014 7:10 pm

Hi Guys,
I have some level differences on my "new" SC 6000 that I would like to fix:
1) when I connect the tape returns to ch. 1-8 with an EDAC loom I have about 6dB less gain on chn. 3; First thought: the EDAC loom. but its fine on ch. 9-16 and 17-24, so its not the cable. second thought: it's the channel strip. but when I plug the same output of my interface directly into the patchbay on ch. 3, the level is same as all others.
so the problem must be somewhere between the EDAC connector of ch. 1-8 on the rear, and the patchbay. no? so:
- how can I access the EDAC PCB without taking out all the channels? can I just unscrew the backplate with the Connector and pull it out to the back?
- what would be the next option - change the flatband-cable, resolder the edac or what else is it?

2) the output bus 5-6 has also 6 dB less gain than all other busses (both L and R), on the patchbay outs as well as on the tape sends. I will check tomorrow again if the gain loss is only present at the bus output or also on the bus sends, but whatelse / whererelse can I search the fault??

thanks for your help!
mark
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Re: SC6000: 6dB loss between EDAC and Patchbay

Postby Jim Williams » Tue Feb 25, 2014 11:31 am

If you lose -6 db, you have a missing connection to one of the balanced inputs. Same applies to the balanced outputs. Check connections with a continuity meter, a dvm set to low ohms with the beeper.
Jim Williams
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Re: SC6000: 6dB loss between EDAC and Patchbay

Postby mokkinger » Tue Feb 25, 2014 7:45 pm

Thanks Jim, I knew it must be something like that... so today I checked all connectors and cables, the patchbay and also switched channels etc, and then I found out that the bus group was set to -10db internally, so I switched that and now the output on that group is fine. but I couldn't find the fault on ch. 3:

maybe I still dont get from where I should measure for continuity - could you give me a hint where to look at?

>> the rear panel connects to the patchbay via ribbon cable and with a multi-connector into the channel strip.. the pre works fine, and since the input level from the patchbay is also okay it has to be something before the patchbay-module-connection, no?

>> the edac connector for the tape return also goes into the patchbay, and is normalled to the channel input, so I can break the connection by direct plugging signals directly into the patchbay. doesn't that mean the problem is somewhere between the edac and the patchbay wiring? then it would be a ribbon cable, no?
but now: how can I trace this down to the faulty point?

thanks, mark
mokkinger
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Re: SC6000: 6dB loss between EDAC and Patchbay

Postby mokkinger » Thu Feb 27, 2014 7:39 pm

Hi Jim,
just wanted to give you an update on that issue:
I traced down the problem to the patchbay, some dirt in the input socket blocked the + signal, so after cleaning the patchbay with contact cleaner and a bantam plug all is fine now!
the group was just set to -10 so after switching back to +4 all output levels are now fine as well!
thanks for the hint, it helped me track down the fault to the point!

best regards,
mark
mokkinger
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Posts: 31
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