Seventh Circle Audio

Just wondering if any one else is having a similar problem mounting the modules.

This actually applies to my n72 also, but I'm not having the same electrical problems.

The jist: The fine gain adjustment attenuators have too large a diameter to comfortably fit the pre-drilled holes in the chassis. Because of this, the entire face plate bows a little.

The problem I encountered is this: Because of this, the cards don't sit properly. I went to test it, and the card had the same problem (no phantom) after getting it repaired once by Tim. (Before, I had shorted two pins of my opamp testing voltages when it didn't work before, and voila...meltdown.) I took the card out, tested it on the bench, and it was fine. Until I took it out of the panavise, and like an IDIOT let a black lead in the molex connector came loose. I think I melted the A12 again.

I guess I have a few questions:

1. If molex pin 4 is disconnected (with the power on ), can anyone imagine what melted first? I can feel heat off of the card. The pre only hums now. Strange, I still measure approx. 18 volts on pins 3/5 of the Avedis 1122.

2. The N72 also seemed to act up a bit during the meltdown two. I heard a bit of spurious noise (which is now gone), and the fine gain adjust doesn't seem as sensitive as it was. Or, I'm now crazy and paranoid. It still sounds very, very nice.

2. Any one else have this faceplate problem? Can I go ahead and dremel a very slightly larger hole to accomodate the resistor/attenuator. What is the relationship between grounding and the xlr's/attenuators?

I want to love my SeventhCircle gear.

I'm expecting everyone to think I'm a dummy. 'Cause I am. Still, I'll absolutely go to chump city for this as I'm a $1000 into this box.

I just want to understand. Badly. Violently.

Thanks,

kelly

I found that I needed to remove the powder coating inside the holes in the front panel, then things fit nicely. I used an electric drill, and didn't remove any metal.

I did the same to all the holes on the front panel, including the power switch hole. I jut used an X-acto knofe to scrape the holes down to the metal. THe holes were probably exactly the right size before poweder coating, and need to be cleaned before mounting.

This is a known issue with powder coating. My dad designs and build parts for race cars and always has to clean out the holes after poweder coating.

I do not think there is a relationship between mounting the modules and ground.

Shane

Man, is any of this mentioned on the site?

I mean, I may not have great aptitude for this, but I wish I'd known this.

I guess this is the level of "common knowledge" required to do this this stuff. Then again, maybe it's on the site somewhere.

kb

I agree about the holes, they need to be cleaned before you mount the panel. Not just because it won't fit over the control bushings, but also to make sure the metal bits of the rotary switches are gounded. It's not explicitly spelled out in the instructions, but it's why "hole reamer" is listed as one of the metalworking tools you should have. As the above posters say, you can use other methods.

It sounds like you've got some bad Molex crimps as well. I'd pull the contacts out of the housings and solder them, just to make sure you don't have any intermittent power problems.

Once the above is straightened out, pull the op-amp out of the board and apply power. Make sure you're measuring +/-18V at the op-amp socket. If you're only getting one of the supply rails, I'd look for a shorted tantalum bypass cap. They're the yellow gumdrops right next to the op-amp. Let us know what you find.

Thanks a lot, Tim. I'll check into the op amp issue when I get home from work.

I didn't mean to imply that the instructions aren't conclusive, it's just that I'm a big dummy and I need every little stupid thing spelled out. My problem, not yours: these are sold as DIY project. I'm going to start my own Melt-It-Yourself kit.



kb