Sound Skulptor forums

Build help and troubleshooting => CP4500 Stereo Bus Compressor => Topic started by: jd.musicology on September 13, 2024, 11:08:40 PM

Title: No output when engaged
Post by: jd.musicology on September 13, 2024, 11:08:40 PM
Hello 1st time builder here. I have built amplifiers and microphones with great success so I know how to use an iron. I'm going through the setup guide, at step 5 all the voltages check out within tolerance. Step 6 I get the sine source going and adjusted to 2 VAC. When I engage the unit 0 V. I can confirm listening to the audio I hear it then engage the unit, no sound. Voltages at TP1 .999, TP2 .008, TP3 1.002. Any help is appreciated!
Title: Re: No output when engaged
Post by: JPK on September 14, 2024, 12:21:55 PM
Do you have the jumper JMP1 inserted ?
Can you report the voltages you get from here (https://www.soundskulptor.com/forum/index.php?topic=3.msg3#msg3)?
Title: Re: No output when engaged
Post by: jd.musicology on September 16, 2024, 09:02:32 PM
Yes JMP1 is inserted. I'm using Studio One to generate the tone. I can't get it to output 3 VAC. Here are the measurements:
1.1-
  • V+ =+15 to +16VDC,15.95VDC
  • V-  =-15 to -16VDC), -15.92VDC
  • +12V = +11.1 to +12.9VDC, 11.73VDC
  • -12V  = -11.1 to -12.9VDC
-11.83VDC
1.2
TP1, TP2, TP3, TP4, TP11, TP12 = 0VDC  TP1 -0.1mV TP2 0v TP3 0v TP4 -0.6mV
TP11 8.2mV TP12 14.54V

1.3
TP12 goes from 0 to -2.3VDC
Stays at 14.5V
1.4
TP13 goes from -1.8V to +2.8VDC
-1.78 to 2.86VDC
1.5
TP5 goes from +0.35VDC to -1.2VDC -1.5VDC to 342mV DC

Title: Re: No output when engaged
Post by: JPK on September 17, 2024, 10:23:54 AM
TP12 14.54V
Does the DC voltage on TP12 goes to 0V when turning the MIX pot CCW to 0?
Check value, direction and solder joints of U22, P3, R90...R94.
Title: Re: No output when engaged
Post by: jd.musicology on September 17, 2024, 11:19:50 PM
Found it! I got a little lazy on two of the U22 pins, re-soldered them and everything works now. Sounds great! Thanks for the fix.:):)
Title: Re: No output when engaged
Post by: JPK on September 19, 2024, 10:06:16 AM
(https://fonts.gstatic.com/s/e/notoemoji/15.1/1f44d/72.png)