Phantom Power Board Problem

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Chris F

Chris F

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I've been recording with the following setup for a while now: Condenser mics---> Soundcraft Spirit M12 board---> MOTU 1224 ---> Digital Performer (Quicksilver G4). I've always gotten decent results, and had no problems with this setup.

Just today, I was getting ready to record an acoustic project when I noticed that there was a low frequency hum in all of the input signals. After some time spent troubleshooting, I discovered that the hum was coming from the phantom power supplied by the board - when I used a cheap Rolls phantom power box to power the mics, the board pres sounded fine, but as soon as I turned on the board's phantom switch, the hum was there.

So I guess I wondering what needs to happen next...can the phantom power supply on the board be repaired, or is that cost prohibitive on a board in that price range? If it can't be repaired, is there a reasonable priced phantom power supply for 8 channels that I could use to rout the signal through, or would I be better off looking at other options? I'm not much of a techie, but I'm willing to do what ever needs to be done to get the system up and running again. As is, the hum wouldn't allow any recording of any quality. Any and all ideas welcome!
 
Depends on what's wrong, but I'd say it's worth having someone look at it, at least. It may be an easy fix. Some repair places have free evals, or a standard bench charge for fault-finding. I'm guessing it's out of warranty?
 
It's out of warranty for sure. Mostly I use it for the pres, and for in/out routing (ex. - I have A CD burner, MD deck, CD player, drum machine, and the stereo outs from the 1224 hooked up to the board, and I use it to rout and control the signals). The only place the phantom power comes into play is on the input signal for condenser mics. If there was, for example, a decent 8-channel rackmount preamp with phantom power that was under about $1K, I could wire that directly into the 1224 and then just rout the output signals as I wanted from there. This would be an nice solution if those pres sounded even marginally better than the soundcraft pres in the board. Otherwise, I guess I'm better off trying to get the board phantom repaired. I guess my questions on this track would be what kind of place to take it to, and whether it's worth it to take a $700 board in for that kind of repair.
 
LOL. I don't know enough about 8 channel pres to say. A bunch have been reviewed here, and also have been compared to various mixer pres. You can search or start a new thread looking for some help.
Take it to a place that services pro-audio, and has some experience with mixers. There have to be some in your area. I searched google and found Knight audio, they are in Jeffersontown, and are Kurzweil authorized, so they are at least familiar with pro audio. That might be a good place to start.

Worth fixing? Hard to say. It may just be a bad solder joint, a quick easy repair. It starts to get pretty vague, though. I just put $200 into a mixer that I could maybe sell for $150. That's what I paid for it, actually. It's old, but I love it. If I sell it, I lose $50. But it was worth it to me, as I couldn't get anything as good for the same money, and couldn't spend more than that $200.

You are going to take the hit on the repair if you sell the thing, whether you pay for it now or drop the sell price to reflect the needed repair cost. An estimate will be good either way to help you decide. Maybe you can fix the board and get new pres.

In your case, find out if you can get an 8 channel pre that is an upgrade for the money you can spend, if that is something you are thinking about. Then decide whether or not you want to fix the board, or spend the money on new pres.
 
Thanks for taking the time to reply. I feel a little silly for having even asked a couple of the questions - it's just that while I am farily proficient at using the board for its intended purpose, I have no idea how complex the inner workings are, nor do I really want to know. I guess I was just wondering whether anybody knows if the phantom power unit in a relatively inexpensive board such as this is likely to be an easily accessible part that is easily repaired/replaced, or whether trying to work on that part of a mass-produced unit like the M12 is opening a can of worms similar to getting so many electronics items reparied these days...you know, where you take it in and the repair person says, "I'll be happy to repair it, but it's likely to cost as much as a new one".

Come to think of it, there is a place not too far away that has worked on some of my live gear in the past. I'll ask my favorite recording engineer (I'm mainly a performer, and the guy at the studio I use is a wizard when it comes to "getting my sound") what he thinks is the right thing to do. In the meantime, I may just try a thread about 8-channel pres that might be an upgrade to see if that's a viable option as well. Thanks again! I suppose my "Rep points" (whatever the **** those may be) are likely to go down because of this thread... :D
 
I know what you mean. If it was a boombox, I would have told you to junk it and not look back. Comsumer stuff is a pain in the ass, not really repair friendly, for the most part.
Phantom power supplies aren't that complex, and are generally near the main p/s, hopefully fairly easy to get to. Cheap parts, too, usually. Labor is gonna be the big factor.

Screw your rep. You are a performer, not a tech. Me, I make a part of my living from people who don't want to know how things work. Hell, most people don't even want to know what I did, just that it is fixed. :D And you may have asked a question someone else was scared to. :)
 
I had the same problem with one of my ADA8000s recently. My electrician friend opened up the box and in about two seconds he traced the problem to one of the electrolytic capacitors which had leaked. The fix was cheap, 1 euro for a new 200ufd/100V capacitor and a pint of beer for labor. If you have a little soldering experience and are not afraid to open up the mixer a leaked capacitor is pretty easy to spot and replace by oneself.
 
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