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« Last post by jfurgason on May 16, 2022, 02:07:09 PM »
Yep, I did the distortion calibration and was seeing the correct AC voltage pin 6 on IC10. I can’t seem to get the compressor trim to get the right value, at its maximum and minimum ends I’m seeing between 0.244 and 0.29 VAC. I’ve reflowed what I can reach, rewired everything, and rechecked all resistor values and remeasured all chips and transistors. Power supply is still good, getting the proper +/-15V at the test points. Here are any readings not in spec with what voltage is expected per Aion’s voltage doc.
All DC voltages
IC 4 (I’m using OPA2134 instead of 4558)
1 = 0V (should be -0.02V)
2 = 0
3 = 0
4 = -15.17
5 = 0
6 = 0
7 = 0.009
8 = 14.96
IC 5 (OPA2134)
1 = 0 (should be 0.01)
2 = 0 (should be 0.01)
3 = 0 (should be 0.01)
4 = -15.17
5 = 0 (should be 0.01)
6 = -0.9 (should be 0)
7 = 0
8 = 14.96
IC6 (OPA2134)
1 = 0 (should be -0.05)
2 = 0
3 = 0
4 = -15.17
5 = 0
6 = 0
7 = 0 (should be -0.06)
8 = 14.96
IC7 (OPA2134)
1 = 0 (should be -0.04)
2 = 0
3 = 0
4 = -15.17
5 = 0
6 = 0
7 = 0 (should be -0.05)
8 = 14.96
IC8 (OPA2134)
1 = 0 (should be -0.03)
2 = 0
3 = 0
4 = -15.17
5 = 0
6 = 0
7 = 0 (should be -0.02)
8 = 14.96
IC11 (CA3080)
1 = 0
2 = 0
3 = 0
4 = -15.17
5 = -14.62
6 = -0.09 (should be 0.23)
7 = 14.96
8 = 0
IC12 (OPA2134)
1 = -0.003 (should be 0)
2 = 0
3 = 0
4 = -15.17
5 = 0
6 = 0
7 = 0.004 (should be 0)
8 = 14.96
IC13 (LM741)
1 = -15.16
2 = 0
3 = 0
4 = -15.16
5 = -15.16
6 = 0.008 (should be 0.02)
7 = 14.96
8 = 0
All other ICs are showing what is expected
Transistors
Q1 (MMBF5457)
D = 14.96
S = -0.08 (should be 0.02)
G = -0.1 (should be -0.02)
Q2 (2N3906)
1 = 0
2 = -0.006 (should be 0)
3 = 14.58
Q3 (MPSA13) these values all look correct
1 = -15.17
2 = -14.43
3 = -0.369
QX1
1 = 0.291 (should be 0.4)
2 = 0.792 (should be 0.9)
3 = 14.91
QX2
1 = -0.332 (should be -0.22)
2 = 0.29 (should be 0.4)
3 = 13.48
Tested on a 9VAC supply with the distortion trimmer properly calibrated. These were the values that jumped out to me, some of the discrepancies are probably within acceptable variance, but I’m including them just to be through. Maybe this helps point to a problem area? I might try subbing in 4558 chips for my 2134 chips and see if that does anything. I may also try new Q1-3 as well. Appreciate any help or insight on this one
Cheers