Mixer repair

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RideTheCrash

RideTheCrash

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Board: Audiopro 16-S made in June 1983. 16 channels. Made as a live sound board.

I am currently installing new faders for this board because the current ones are old and the lube has stripped off. Fortunately Yorkville, who made this board, had some left in stock, which I ordered.

The next problem I want to tackle are channel issues.

Channel 6 is very quiet compared to the rest, and I searched and searched but couldn't find where I read this, but it's been said this could be a leaky capacitor? Channel 9 which doesn't really get use (my soundcard only hooks up to the first 8) is fried. If it doesn't get fixed, that's okay, but I'd still like to get it working.

Now I know next to nothing about electronics (as in, the guts of equipment), so I wouldn't know where to look to see if something was visually wrong. Fortunately my girlfriend's dad has been an electrician for years, so if you guys can pinpoint a problem, I can get his help.

Yorkville has offered for me to ship it into them or get it there somehow, but they are located like 2-3 hours away and I won't really have time to get out there anyhow. Plus shipping this thing would be next to impossible, it's a huge mother built into a flightcase.

This is the insides: http://www.freewebtown.com/smsessions/audioproguts.jpg

Channel 6 is kind out of out of view, and channel 9 is not the one directly under the stamped 9, but the one next to it, where there is that grey-ish coloured stuff next to those spike thingys on the circuit board (I sure know my lingo huh?).

Thanks.
 
Channels 8 and 9, and possibly 10 have had repairs done on them. Note the different colored capacitor on channel 8. The extreme heat from a soldering iron did the damage to the buss card on channel 9.

If the capacitor went out on 8 then it could very well be suspect on 6. I'd have a tech check the values on it.
 
I'm not quite sure what you meant by your last statement, but I will have my girlfriend's dad look at it. Good eyes...I didn't notice there are two darker blue capacitors (I didn't even know what the capacitors were).

So I'll assume it's the capacitors for channel 6...I could get these replaced by someone? As for channel 9, that is unfortunate, I'm like this board's 3rd owner so the first guy probably did the repairs. I'm assuming since it's damaged it would have to have a new put in..not an easy job I'd assume, you'd have to remove everything and pull it off...plus I'd have to get a new circuit board.

If that is the case I think I will leave channel 9 alone, seeing as it's hardly used it wouldn't be worth the time and money to drive way up to Yorkville to get it fixed...if they even could fix it.
 
Also, if channel 9 was fried from the heat of the soldering gun...was the soldering done to put the new capacitors in? Because how would I go about having someone put new capacitors in channel 6 by soldering...without frying channel 7?
 
RideTheCrash said:
how would I go about having someone put new capacitors in channel 6 by soldering...without frying channel 7?
If you know what you are doing, you won't burn the board with the soldering iron. It isn't a big deal.
 
I won't know...I wouldn't be doing the soldering. I've never used one so I don't know if heat coming from the gun fried it, or if the guy wasn't very experienced and mucked it up somehow.
 
with all the residue around the solder joints and spotting on that end of the buss board, it looks like the inevitable drink was set on top, or nearby and spilled. The heat of the joints usually evaporates the water and alcohol and leaves the sugary caramel like glue.
 
Interesting. I just checked the insides again and channels 2, 11 and 12 have also had capacitors replaced...which I guess means they've replaced them without screwing up the other buss boards so I should be okay?

This mixer is built into the bottom flight case, so to open it you unscrew 4 large screws on the bottom then open the board upwards, and two arms come down to support it...like the hood of a car. So they probably had a drink nearby anyways...I hope that is the reason it's dead, not because of heat radiating off this gun killed it.

So how does this work exactly -- just out of curosity, do you solder the new capacitors on there after taking off the old ones? It seems there are 3 different ones that have been replaced per channel strip. Would I have to contact Yorkville about capacitors? I'm guessing they are a stock sort of item I could buy at a store.

Is there a ballpark figure on how much that would cost?
 
If you can get the right value cap at an electronics store, I'd be surprised if they were 50 cents each. It really isn't hard, but if you don't know what you are doing there is a good chance of messing it up. Think about it, you have to be able to solder it, that's how all those parts got attached to the board in the first place.

However, with out the proper test equipment, a schematic, and at least some knowledge of electronics, you probably won't get it done.

Take it to a tech.
 
Which is exactly why I don't plan on doing it myself, I would in fact screw it up. I think the manual I have in PDF has schematics, but only for the power supply, I might be able to score some from Yorkville, not sure...

Anyways, it would be my girlfriend's dad doing it most likely, he's been an electrician for 30 some odd years, he could probably do it fine...if not he could probably direct me to someone who could.
 
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