Fixing a crackly channel on mixer

K

KrispyDK

New member
Hello all,

I wonder if anyone could help me?

I have a soundcraft spirit folio 12/2 and it has begun crackling consistently rendering it pretty useless.

I've narrowed the crackling down to channel 9/10 which is one of it's two stereo channels. This channel has become totally kaput - nothing coming through it but crackle and fuzz. When I pan left and right on this channel the crackle follows it through the main channel.

The mixer has a PFL button on each channel which allows you to monitor the signal pre-fader. With this pressed on channel 9/10, the channel works fine - no crackle and clean signal. So I figure the problem is something to do with the channels fader?

Anyway, I can live without this channel. Is there an easy way of 'disabling' it via the circuit board leaving the rest of the channels intact? This would allow the rest of the board to work as it did before.

Currently, the only the board is usable is by panning channel 9/10 to the left and muting the main left channel. Everything else gets panned to the right and comes through fine. Unfortunately, that leaves me with a 1 channel mono mixer!

Any help or guidance well be gratefully received.

Cheers.
 
Here's what I've done that has worked on many mixers. Whether it will depends on the type of fader and if it's damaged or just dirty:

I use Deoxit D5 http://cgi.ebay.com/HOSA-CLEANERS-L...emQQptZLH_DefaultDomain_0?hash=item5ad7f713a0
and spray a small amount in the slot where the fader is, with the nozel on "Low" (the spray is adjustable on those cans). Then I move the fader up and down. And while I move it up and down I push it to the left a bit, then to the right, then down a bit, and even pull it up a bit, all while moving it up and down. The idea is that there's some crap on the contacts that needs to be cleaned.

I do this to a lot of my stuff, all my cable ends, jacks, pots and power strips have a light coating of Deoxit D5 (the red can) on them. Sometimes you can hear a purer high end after you spray it.

80% of men have experienced new hair growth with Deoxit D5 :)
 
Thanks Dinty.

I've been performing that maneuver minus the spray for a while with no effect. I picked the mixer up second hand recently and the guy I bought it from gave it a good spray when I went to collect it.

What I don't understand is how the crackling through the main channel remains the same volume even with the fader on the busted channel pulled all the way down?
 
I'm not familiar with that particular model, it's been a number of years since I repaired audio equipment for a living. "Back in the day" it was pretty common for 4558 op amps to do what you describe. Generally it's a pretty simple matter for an experienced audio repair tech to fix.
 
It's always worth taking something apart and seeing if there's any visible damage... cracked solder joints etc...
 
So, if taking it to a pro audio repairer to replace the op amp is not an option, are there any other options other than binning the thing???
 
Target practice. :laughings:
Maybe you should just consider getting a new mixer.
Purchasing used ....I personally don't like, you end up buying someone else s problems.
 
KrispyDK said:
So, if taking it to a pro audio repairer to replace the op amp is not an option, are there any other options other than binning the thing???
Click to expand...

Before you trash it, take it apart and look for visible damage. I had a tv once that stopped working and I took it apart and saw a burnt resistor, replaced it and it worked for a long time. There's a chance that when you take that thing apart that the fader case is snapped apart and can be pushed back together, or maybe where it's mounted on the pc board is cracked and can be resoldered. Look at the pc board really carefully with a light and even a magnifying glass.

My neighbor had a Dodge that wouldn't start. The dealer worked on it for weeks and couldn't find the problem and finally towed the car back to his house and told him to sell it (!). He asked me to look at it and I pulled the battery to charge it and saw a burnt wire under the battery and fixed it. The car started and was driven for several years. I'm no genius but here's the thing: when something fucks up it's way more often something stupid-simple than complicated.

As for all that talk of Deoxit D5 growing hair, MOFO Pro said it's on his hands, omtayslick and moresound had more inapropriate comments... I shouldn't have started that, there's people here looking for solid advice, not some immature attempts at comedy, so I'm sorry for starting that. Seriously.

That being said, I haven't tried it, but I heard the can goes in your ass easier if you leave the cap on. :)
 
KrispyDK said:
Hello all,

I wonder if anyone could help me?

I have a soundcraft spirit folio 12/2 and it has begun crackling consistently rendering it pretty useless.

I've narrowed the crackling down to channel 9/10 which is one of it's two stereo channels. This channel has become totally kaput - nothing coming through it but crackle and fuzz. When I pan left and right on this channel the crackle follows it through the main channel.

The mixer has a PFL button on each channel which allows you to monitor the signal pre-fader. With this pressed on channel 9/10, the channel works fine - no crackle and clean signal. So I figure the problem is something to do with the channels fader?

Anyway, I can live without this channel. Is there an easy way of 'disabling' it via the circuit board leaving the rest of the channels intact? This would allow the rest of the board to work as it did before.

Currently, the only the board is usable is by panning channel 9/10 to the left and muting the main left channel. Everything else gets panned to the right and comes through fine. Unfortunately, that leaves me with a 1 channel mono mixer!

Any help or guidance well be gratefully received.

Cheers.
Click to expand...

No help or guidance, but a month ago, my (much smaller) Soundcraft mixer (Compact 4) started crackling on channel two. Today I tried the spray contact cleaner (not Deoxit, another brand), and tomorrow I'll find out if it worked. Whether it works or not, I'm in the market for a larger mixer (I want 4 ins, 4 outs, inserts and whatever ins and outs I'll need for a MIDI keyboard) but since I read about your Soundcraft woes, I'm wary about brand loyalty in this case. Suggestions, anyone?
 
Hello all,

Dobro - I've only ever heard good things about soundcraft - particularly down at our end of the market (I would have got a compact 4 if I could have found one). Perhaps we are just a couple of exceptions.

Here's the deal with my Folio (and my set up in general). I've been slowly cobbling bits together for a home studio. ebay has been a revelation to me. I got hold of the folio via ebay from a production company in the UK that were selling on their retired gear. The Folio was far from new and obviously used but visually in a good state. When I went to collect it the guy plugged it in and checked every channel in front of me. The stereo channel that's giving me grief now sounded obviously 'muffled' when he tested it. He must have emptied a quarter of a can of the UK equivalent of Deoxit straight into the fader while vigorously pushing the fader up and down but it didn't solve the problem. However, the crackling wasn't there while I was with him. He offered to knock some more of the agreed price because of the muffled channel and that seemed reasonable to me. I didn't need the stereo channel and didn't think the problem would cause constant crackling through the main channel. I still had 8 good quality mic pre strips and a stereo channel - all for £50.

It was only after a couple of days at home with it that the crackle begun to raise it's head. Right now the channel is dead except for the crackle. That is unless you check the pre fade signal - the pre fade signal is fine. So the problem is definitely somewhere in the fader.

LDS's suggestion that it 'Sounds like a bad op amp chip in the post fader section of the channel' has made sense to me.

I was wondering whether, if I can locate and identify said op amp, will removing it off of the board render the whole mixer useless or just that channel? I'm hoping that it will just kill that channel and, in turn, the crackle. However, because the crackle seems to spill into the main channel even with the crackle channel's volume off, it suggests that removing it my break some kind of circuit. I wish I'd listened in physics while I was at school.

The other option would be to find a new op amp and solder it to the board. But where to find one?

On a brighter note, I treated myself to an M-Audio DMP3 and a Studio Projects B1 today. I know, not top end stuff but it is by my standards! I think with these, a Delta 44 and all the outboards I've been picking up for peanuts on ebay, I may not need the mixer at all.

And Dinty, you had actually suckered me in with your humility earlier. Then I read about your Deoxit fixation and it put me right off my tea and toast. Thanks.
 
By the way Dinty - your man, Mike Lundy, is a dead ringer for Alan Pardew.

That won't mean much to either of you but it will to anyone over here where football is still played with your feet!
 
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