nosaj 10/8/2017 1:19 PM
studiomaster club 2000 182 mixer
I got this mixer they were complaining about output dropping out. So I cleaned all the contacts.

During Testing the 48 phantom power was on and I had an ipod with xlr cable into the mic input well it smoke c1 and c2 causing lots of noise replace them . Vol is slighly lower compared to the other channels. But on gain know when it hit 60db(on the dial gets lots of noise, back knob off just a hair and sound is fine. No other knobs do this.) Is there something else I could have damaged?

Thanks,
nosaj
input schem included[ATTACH=CONFIG]45231[/ATTACH]
 
Leo_Gnardo 10/8/2017 1:56 PM
Quote Originally Posted by nosaj View Post
During Testing the 48 phantom power was on and I had an ipod with xlr cable into the mic input well it smoke c1 and c2 causing lots of noise replace them .
Phantom power rule #1: if you don't NEED phantom, DON'T HAVE IT ON!

Your ipod outputs are not balanced, furthermore don't need phantom to work. So ... you were shorting phantom to ground via cable adapters that do not magically turn an unbalanced signal into a balanced one.

Mixers that apply phantom to all inputs at once, drive me crazy = looking for trouble and they inevitably find it.

Although the phantom DC blocking caps C6 & C7 are rated 63V, I find caps used for this function often fail especially when phantom is misused, iow applied to unbalanced signal sources. Plugging, unplugging, and intermittent connections on the mic lines can apparently cause spikes in excess of the caps' rated voltage then they start leaking. I'd replace C6 & C7 with parts rated for 100V, see if that helps.
 
nosaj 10/8/2017 3:38 PM
Quote Originally Posted by Leo_Gnardo View Post
Phantom power rule #1: if you don't NEED phantom, DON'T HAVE IT ON!

Your ipod outputs are not balanced, furthermore don't need phantom to work. So ... you were shorting phantom to ground via cable adapters that do not magically turn an unbalanced signal into a balanced one.

Mixers that apply phantom to all inputs at once, drive me crazy = looking for trouble and they inevitably find it.

Although the phantom DC blocking caps C6 & C7 are rated 63V, I find caps used for this function often fail especially when phantom is misused, iow applied to unbalanced signal sources. Plugging, unplugging, and intermittent connections on the mic lines can apparently cause spikes in excess of the caps' rated voltage then they start leaking. I'd replace C6 & C7 with parts rated for 100V, see if that helps.
Bingo that brought the vol back up and removed the noise when gain is maxed.
Thanks so much.
Will have to start collecting the Rules like on NCIS.

nosaj
 
Leo_Gnardo 10/8/2017 4:03 PM
Quote Originally Posted by nosaj View Post
Will have to start collecting the Rules like on NCIS.
One of my fave shows, and I don't even have a TV. I'm glad to see the solution worked for you.

Phantom going to the wrong places can also wreck the signal source. It would have been a shame if the ipod output was damaged.

Here's another for you & anyone else reading. If you have a phantom powered mic or DI, and it can also be operated by battery, remove the battery when you use phantom. Credit Tom Foehlinger at Clair Bro's, he taught me this one 30+ years ago. Tom was removing batteries from a bunch of brand new Countryman 85 DI boxes so I asked why. Phantom will try to charge the battery and the sound quality will suffer. Maybe some dual-power devices can deal with this but why take a chance.
 
nosaj 10/8/2017 4:14 PM
Quote Originally Posted by Leo_Gnardo View Post
One of my fave shows, and I don't even have a TV. I'm glad to see the solution worked for you.

Phantom going to the wrong places can also wreck the signal source. It would have been a shame if the ipod output was damaged.

Here's another for you & anyone else reading. If you have a phantom powered mic or DI, and it can also be operated by battery, remove the battery when you use phantom. Credit Tom Foehlinger at Clair Bro's, he taught me this one 30+ years ago. Tom was removing batteries from a bunch of brand new Countryman 85 DI boxes so I asked why. Phantom will try to charge the battery and the sound quality will suffer. Maybe some dual-power devices can deal with this but why take a chance.
That could be particulary nasty if it's not a rechargeable battery, no?

Thanks,
nosaj
 
Leo_Gnardo 10/8/2017 4:53 PM
Quote Originally Posted by nosaj View Post
That could be particulary nasty if it's not a rechargeable battery, no?
One day early 2000's I was troubleshooting some crappy signals on a concert stage, and found about half a dozen Countryman 85 DI's in use that did have batteries in. Some of them were well discharged, down to 2 or 3 volts. Luckily none had leaked, and none were rechargeable either. With the batteries removed, all those DI's started delivering good audio. They belonged to a major PA company - one that does sound at major Washington DC area political events and NY city Times Square New Years parties - they should have known better! But they didn't... Maybe that's what happened to Mariah Carey's vocal mic last New Year's eve. The CEO of that PA company claimed in the next day's news "it wasn't us!!!" Naaaaw... sure it wasn't... right!
 
Enzo 10/8/2017 5:59 PM
This will be Abby's last season. NCIS will have to hire ten people to do all the stuff she did. She's my hero.