EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: pbloem on May 30, 2019, 08:39:52 am
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Hi
I'm trying to revive a Advantest R3131 (no A) from the dead. The previous owner tried to replace a 4072 OpAmp on the IF-LOG board, 4th section of the mixer.
But he failed and teared of 2 traces.
He gave up and gave the unit to me (what a nice guy!). Without any schematics to go from, I'm reaching out to this community in the hope some one could please
give me an indication where these two pins need to go.
The designation of the OpAmp is U4 and the traces of pins 6 and 7 are gone.
From hi-res pictures i found online, it seems that these pins could have a trace between them...
Thanks Pascal
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So I already fixed the Total Gain Failure by replacing a R120 (a 390 ohm resistor) with an 680 ohm resistor (as already stated in previous posts on this board).
Now there is still the matter of the IF ATT failure, which I suppose is where the two broken pins of U4 come into play...
Still hoping there is someone on this forum who could help me find the correct connection for those two pins
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The uPC4072 is a double op-amp and the connection between out (7) and -in (6) turns it into a unitary gain buffer.
If I see right in the picture the pin +in(5) seems to be connected to gnd then this is probably an unused section of the IC.
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Thank you for your reply picburner...
Haven't looked at it that way, was to focused on finding (non existing) trace path.
So I still have to find the real problem, that is giving the IF ATT Failure, measuring within the unit is dramatic due to the construction.
But I'm going to replace the AD606 opamp in the IF signal path and see if things improve.
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Hi pbloem,
After replacing U1 (AD606) did you have any succes with the repair?