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Need an expert help with Yamaha EMX5016CF power mixer repair

 
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Chikov



Joined: 04 Aug 2008
Posts: 654
Location: Houston,TX

PostPosted: Sat May 27, 2017 5:06 pm    Post subject: Need an expert help with Yamaha EMX5016CF power mixer repair Reply with quote

I was asked to fix powered Yamaha mixing console. It has 2 problems. The biggest one is that there is no output. When I turn in on, almost instantly it shuts down. it sounds that RY401 safety relay clicks and cuts off the power to the rest of the PC boards. When I disconnect the PA board (via 15VDC ribbon cable) the power stays on. Another thing, orange +46VDC terminal, when you plug the PA board, reads close to 68V, but when I unplug the orange wire it drops down to normal +46V. I see no burnt spots or parts and testing the transistors on PA board (if I am doing it correctly) does not show any problems. Does anyone have an experience with solving this kind of problems? Where should I be looking for a source of the problem? I bought of the internet Service manual with schematic, but it did not help much.
second problem - the AUX1 and AUX2 do not have any signal on output, but It might be a separate issue, I'd like to get it to amplify first Smile. If you need to see any schematics, I will be happy to post it too.
Thank you.
Alex.
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WildIowa



Joined: 06 Mar 2004
Posts: 489
Location: Henderson IA

PostPosted: Wed Jun 07, 2017 3:17 am    Post subject: Reply with quote

Totally above my pay grade. Good luck! Old tube stuff much easier to troubleshoot...
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Vic Vega



Joined: 15 Mar 2010
Posts: 1882
Location: SW Idaho

PostPosted: Wed Jun 07, 2017 10:44 am    Post subject: Reply with quote

Without seeing the board or anything, my first guess would be the limiting resistors. If nothing looks burnt, they may still be faulty.
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Kregg



Joined: 22 Apr 2008
Posts: 3333
Location: Atlanta

PostPosted: Wed Jun 07, 2017 11:16 am    Post subject: Reply with quote

According to what I found/read the MG series (not sure which model you're asking about) was very problematic.
Try a model search for equipment failures.
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Chikov



Joined: 04 Aug 2008
Posts: 654
Location: Houston,TX

PostPosted: Fri Jun 09, 2017 8:34 am    Post subject: Reply with quote

Yes, it was harder then I thought... I got a word from Yamaha forum moderator and he said that they just suggest replacing the whole PA board (about $250.00). The guy who owns this board said it is too much money for him... I did learn a lot, got to use my signal tracer, learned more about Transistors. still need to learn more about limiting resistors Smile. I gave him the board back, but I am not as afraid of it anymore Smile. Boy, do they use too much components compare to Tube Amps...
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