Sound Skulptor forums
Build help and troubleshooting => CP5176 FET compressor => Topic started by: Botanicus on December 17, 2023, 11:45:14 PM
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Tested voltages when plugged into extender
Spot on for V+, V-
Was on the Fet Bias step in setup and noticed that with maximum gain out of my DAW only getting 6V on output with IN/OUT maxed and 20 Ratio not the expected 13.5V
Reading through support here I measured L1 and get 5.7V DC whether or not the compressor is on. Seems I have an issue with the DOA.
I tried a JLM 99v DOA I have from another working project and get 1.38V DC at L1.
The SK25 DOA also gets very warm within a minute or two of plugging it in
No Input Signal
- V+ 15.30VDC
- V- -15.79VDC
- TP1 0VDC
- TP2 0VDC
- TP3 0VDC
- TP4 -5.51VDC
- TP5 0VDC
- TP6 -2.44VDC
- TP7 -5.51VDC
100mV 1K Sine IN/OUT MAX Ratio 20
- TP1 0VDC 0.228VAC
- TP2 0VDC 3.02VAC
- TP3 -.015VDC 10.92VAC
- TP4 -5.5 VDC 0VAC
- TP5 0VDC 0VAC
- TP6 -2.44VDC 0VAC
- TP7 -5.5VDC 0VAC
- OUTPUT 5.88 VAC
Ran these tests from the test the sidechain post
AC level on TP3: (MY VALUES WERE DOUBLE SHOWN BELOW)
- Ratio 2 : 0.65 VAC
- Ratio 4 : 1.3 VAC
- Ratio 8 : 2.1 VAC
- Ratio 12 : 3.4 VAC
- Ratio 20 : 5.9 VAC
- Ratio SLAM : 6.6 VAC
DC level on TP4: (MY VALUES WERE SPOT ON)
- Ratio 2 : 0 VDC
- Ratio 4 : -0.5 VDC
- Ratio 8 : -1.3 VDC
- Ratio 12 : -2.5 VDC
- Ratio 20 : -5.5 VDC
- Ratio SLAM : -0.6 VDC
DC level on JMP1 pin 1: (MY VALUES WERE TRIPLE SHOWN BELOW)
- Ratio 2 : 0.6 VDC
- Ratio 4 : 0.9 VDC
- Ratio 8 : 1.2 VDC
- Ratio 12 : 1.9 VDC
- Ratio 20 : 2.3 VDC
- Ratio SLAM : 7.9 VDC
I have checked for bad solder joints and shorts on main board and DOA
Based on above I may have an issue with both DOA and Sidechain circuit
I verified the power transistors were on the right sides of the DOA
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I measured L1 and get 5.7V DC
Bad SK25, it should be 0VDC. You must start here: https://www.soundskulptor.com/forum/index.php?topic=9.0