Hi, I'm working on a Sony receiver where the right channel is barely audible compared to the left. I put a test tone through the CD input and I took my oscilloscope and looked at the input signals on pins 6 and 8 and they match. The output on pin 2 and 3 looks the same as pin 6 where pins 11 and 12 are amplified quite a bit. Is this a clear indication that this IC is bad or could something else be at fault? I pulled out and tested some of the caps like c651, c655 and c565 and they're all within spec. I didn't see anything strange or out of line reading the voltages of all of the pins either.
No, there's a lot more after the IC, there's a limiter loop, booster loop, current detect, power protect etc. I just was thinking this is where I saw the change from L to R happening so isolated it to here. I guess maybe I should look at c653 too since it sits right next to the IC which I think can get pretty hot. Why does this thing not have a heat sink?
Yeah it seems to be D.C. I might need to double check the NF1 voltage as I assume that would influence whether or not that channel is being amplified.
For simplicity's sake, just trying to show the left side. This thing has surround sound so it gets muddy....
Yeah it seems to be D.C. I might need to double check the NF1 voltage as I assume that would influence whether or not that channel is being amplified.
For simplicity's sake, just trying to show the left side. This thing has surround sound so it gets muddy....
I see, it's a driver. The schematics description had me puzzled.
I'm a screwdriver expert at best, but the comp input soldering would interest me. Your muting voltage differs from a sister amp, which shows a different resistor bringing it in. Hows your language skills? http://bbs.hifidiy.net/thread-1268683-1-1.html
If the input signal was the same magnitude to both, and the output differed, I would consider if it's getting hot due to being pulled down elsewhere. It's odd the signal came through, but not amplified at all. The 1.1v is holding though, so it doesn't seem like it's being pulled down. It does seem faulty, but I'm not quite convinced either.
At this point, I might be tempted to cut a few traces, to test it in isolation.
The following stages have me out my depth. It's covered it exclamation marks, and resistors in boxes. Which I can only guess are fuse types. So certainly worth a look, though it might be wishful thinking.
I'm a screwdriver expert at best, but the comp input soldering would interest me. Your muting voltage differs from a sister amp, which shows a different resistor bringing it in. Hows your language skills? http://bbs.hifidiy.net/thread-1268683-1-1.html
If the input signal was the same magnitude to both, and the output differed, I would consider if it's getting hot due to being pulled down elsewhere. It's odd the signal came through, but not amplified at all. The 1.1v is holding though, so it doesn't seem like it's being pulled down. It does seem faulty, but I'm not quite convinced either.
At this point, I might be tempted to cut a few traces, to test it in isolation.
The following stages have me out my depth. It's covered it exclamation marks, and resistors in boxes. Which I can only guess are fuse types. So certainly worth a look, though it might be wishful thinking.
I am sorry I don't know what's going on but went back and re-checked and no longer see any differences of signal coming on or out of this IC. I think I am going to suggest this post be closed or deleted until I find out more about the issue and start a new post then.
