Sound Skulptor forums

Build help and troubleshooting => CP4500 Stereo Bus Compressor => Topic started by: Chiller on March 16, 2023, 11:07:45 AM

Title: CP4500 Threshold doesn't work
Post by: Chiller on March 16, 2023, 11:07:45 AM

Hello,
today the Threshold Poti of my CP4500 stopped working. I can turn it as usual, but it has no effect on the signal. Yesterday everything was fine, so I have no idea, why it stopped working. Any solutions?
Thank you!:D

Title: Re: CP4500 Threshold doesn't work
Post by: JPK on March 16, 2023, 12:01:10 PM

It could be a pot failure or a connection failure between pot and circuit.
The pot voltage can be checked on TP13 (against 0V)
Check step 1.4 here (https://www.soundskulptor.com/forum/index.php?topic=3.msg3#msg3).

Title: Re: CP4500 Threshold doesn't work
Post by: Chiller on March 17, 2023, 09:30:21 AM

Thanks, I've checked it, and it's just 0.45 to 0.55 VDC, when I turn the threshold. The solder points are good... is there another way to check out if it is the pot?
Thank you

Title: Re: CP4500 Threshold doesn't work
Post by: JPK on March 20, 2023, 09:24:12 AM

R95-left pin should go from +12V to -12V when turning the threshold pot.

Title: Re: CP4500 Threshold doesn't work
Post by: Chiller on March 20, 2023, 12:15:10 PM

Yes, that works fine. So the pot is working.

Title: Re: CP4500 Threshold doesn't work
Post by: JPK on March 21, 2023, 09:00:55 AM

So the issue is around U21.
Check solder joints and values of R95...R99, U21.
Try swapping U21 with another OPA2134.

Title: Re: CP4500 Threshold doesn't work
Post by: Chiller on March 22, 2023, 09:42:17 AM

Hi JPK,

I fixed it! Thank you so much for your help. I renewed all solder joints around that area but I think it was a slightly deformed pin of the U21.
Thanks again and have a good day 8):D

Title: Re: CP4500 Threshold doesn't work
Post by: JPK on March 22, 2023, 09:50:40 AM

(https://fonts.gstatic.com/s/e/notoemoji/15.0/1f44d/32.png)