| Description |
BASS EQ:
When boosting the bass, nothing happens, when boosting to +5 db then then there is silence,
when boosting to +5,5 db then, then the audio signal is suddenly audible again.
LOW MID:
EQ and gain is working
HIGHS MID:
When cutting the bass, nothing happens, when cutting to -5 db then then there is silence,
when boosting to -5,5 db then, then the audio signal is suddenly audible again.
HIGHS:
EQ and gain is working
We put a audio sinus-wave into the patchbay (via Mic preamp).
To get a sinus wave: Click in the macro-Button, then you have
16 buttons you can select, select:
- click the button "Osc Tggl" (Its the button on the right side at the bottom)
- click the button "Osc 1K05"
Take a bantam-patchkabel and connect it into "TB Out" from the master-patchbay
and go into the patchbay of the defective channel, put it into "Mic Input".
Now take the schematics of the equalizer:
- EQ D Component Placement.pdf
- Four-Band EQ D0-1.pdf
- Four-Band EQ D0-2.pdf
Have a look at PDF1:
Now we have to search where the sinus get lost.
At U12 Pin 4 we have 920mW it's correct.
At U12 Pin 2 we have 2,64 V instead of 920mW.
At U13 Pin 2 we have 3,84 V instead of 920mW.
I replaced U13,U15,U18. Problem still exists.
At U3 Pin 7 we measure -19,6 Vlt!
Christian say, that the component which have 18V are for example
U1,U4,U11,U16. So i socketed thisones and replace them but the problem
still exists.
Mr. Bremer says i have to checked all opamps that mean all components
with the triangle symbol. Ok, i start now:
I wanted to replace U6,U8,U10, so first a desoldered the U6,U8,U10
at the same time and socketed them.
Now i put exactly the same back (not newer ones).
-> Curiously, everything is now working again!!! Problem is solved!
But why??? We think that is was perhaps the U10.
Because I unsoldered it, it got warm, maybe that's why it's working again?
Really bizarr!!
Comment:
Can be interchanged with one another:
OP275GP
OP271GP
OP5532
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Ok, now 3 month later the problem is back. When changing for example the gain of the middle highs,
at some positions, the complete audio signal gets OFF. In the other positions the audio signal is ON
but the eq isn't working...I continue, now i will change U30.
Mr. Kupfer another technican, who never repair an euphonix,
says he wants to see the problem. Ok, new start.
Mr. Kupfer says...
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