On Wed, Feb 23, 2022 at 07:53 AM, Alex_03 wrote:
This is what I got.
pin 3: 13.80V
pin 4: 13.05V
pin 5: 13.06V
pin 6: 13.83V
pin 12: 27.5V
pin 13: 27.77V
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Most likely U1 is good. You have one Vbe drop from pins 3/6 to pins 4/5 which is correct and collectors at pins 12/13 are balanced.
In the plots you attached I thought there was an imbalance in pin 4/5 voltages but the scales are different and they match. Input section looks fine.?
From a brief analysis of the output stage, pin 13 voltage swing looks too high (2.4Vpp), even pin 12 swing is high . U2 and surrounding components look like a transimpedance stage and should keep pin 12/13 swings very small. Given the signal swings, U2 is not doing its function, but it could be because of bad components around it so it doesn't mean U2 is bad for sure. I recommend looking around U2.?
DC voltages at pins 2/3/5/6/7 may give clues.?
Ozan
