Sound Skulptor forums

Build help and troubleshooting => CP4500 Stereo Bus Compressor => Topic started by: macguy78 on March 16, 2022, 07:34:05 PM

Title: Output issues
Post by: macguy78 on March 16, 2022, 07:34:05 PM

Hello!

I’m having some problems getting my Multimeter to read 2.0VAC. I’ve used my DAW output and the sine tones provided in the Downloads section, tried using an outboard mixer, and reflowed the output sections on the PCB; no matter what I get a reading of 0.033.
I am stumped at this point and could really use some help. I’m not well versed in using a multimeter either so I could use some guidance as well. 
Thanks! :)

Title: Re: Output issues
Post by: JPK on March 18, 2022, 12:04:37 PM

Check if the output signal is present on TP2, against 0V. It is divided by 2 compared to the XLR output.

Title: Re: Output issues
Post by: macguy78 on March 18, 2022, 06:16:14 PM

I located the test points and with ONLY the red probe on TP2, the highest i got was .147VAC. The other images show my mixer audio cranked all the way up (with a 1K sine going through it) and the red probe on TP2. As soon as i touched the black probe on 0V, the reading drops to zero. 


(https://i.imgur.com/KEMpwI3.jpg)
(https://i.imgur.com/L1NpKcT.jpg)
(https://i.imgur.com/Zh62OHj.jpg)
(https://i.imgur.com/Vq03Uql.jpg)

Title: Re: Output issues
Post by: JPK on March 19, 2022, 06:09:34 PM

I located the test points and with ONLY the red probe on TP2
You absolutely need 2 probes to get a measure. In this case the black probe goes to 0V.
Now check if you can measure the input signal on TP1 (against 0V also).
And move on with the voltages check here (https://www.soundskulptor.com/forum/index.php?topic=3.msg3#msg3).

Title: Re: Output issues
Post by: macguy78 on March 19, 2022, 06:20:45 PM

Ok I’ll try those out. 

Title: Re: Output issues
Post by: macguy78 on March 20, 2022, 03:52:07 AM

I reflowed the components and got a proper reading. My CP4500 is calibrated! Thanks for your help!

Title: Re: Output issues
Post by: macguy78 on March 21, 2022, 04:12:43 AM

I’ve tried calibrating a couple of times and at Step 7, I can’t get the VU to read zero no matter how much I turn the output trimmer down. Any idea what I should be looking for? 

Title: Re: Output issues
Post by: JPK on March 21, 2022, 09:21:45 AM

The trimmer T1 doesn't have an effect on the Vu meter.
In step 7 the pots should be in the initial position, with threshold at +15.
Are you saying the meter doesn't stay at 0?

Title: Re: Output issues
Post by: macguy78 on March 21, 2022, 12:20:50 PM

When the compressor is not engaged, it sits at zero but when it is engaged, the meter moves up a little. 

Title: Re: Output issues
Post by: JPK on March 25, 2022, 06:46:23 PM

You will need to do these measurements: https://www.soundskulptor.com/forum/index.php?topic=3.msg3#msg3

Title: Re: Output issues
Post by: forcemusicgroup on April 08, 2022, 06:47:59 AM

CP4500

TP 12 - 2.38v
At step 3 nothing moves on the DMM except .001
Low output

 - Voltage checks fine. 
TP1, TP2, TP3, TP4, TP11, TP12 = 0VDC


when you have a moment can I get your assistance.... thanks 

Title: Re: Output issues
Post by: JPK on April 08, 2022, 04:12:20 PM

Sorry, I do not understand. What are you results on steps 2 and 3?

Voltages check step 3:
how is TP12 when you rotate Makeup?

Title: Re: Output issues
Post by: forcemusicgroup on April 08, 2022, 05:10:26 PM

Voltage check is fine. 

Step 2 all readings are normal except tp 12

When rotating the threshold knob the meter changes -.001 

Title: Re: Output issues
Post by: JPK on April 09, 2022, 04:06:57 PM

Step 2 all readings are normal except tp 12
Do you mean TP12 is not 0?

When rotating the threshold knob the meter changes -.001

TP12 voltage depends on MAKUP, not THRESHOLD.
TP13 voltage depends on THRESHOLD.