Sound Skulptor forums

Build help and troubleshooting => CP4500 Stereo Bus Compressor => Topic started by: farrellamps on July 04, 2023, 12:24:19 AM

Title: Positive - Negative Rail Issues
Post by: farrellamps on July 04, 2023, 12:24:19 AM

Just finalized my build, when i power up using a rig that connects to the card (using a card edge connector) I have the following issue: No CP4500 connected I have +- 15.6v , even with none of the opamps or line drivers inserted, only the voltage regulators, the voltages become unbalanced, the negative rail goes to almoat -20vdc and the positive goes to 9vdc. I have tripple checked all of it.

Title: Re: Positive - Negative Rail Issues
Post by: farrellamps on July 04, 2023, 12:53:05 AM

Update: Removed the two 78L12 and 79L12 regulators and the power supply is back balanced, second channel does not have the issue. 

Title: Re: Positive - Negative Rail Issues
Post by: JPK on July 04, 2023, 09:24:53 AM

Look for a short circuit (with your ohmmeter) between the +12V pin and the other power pins (0V, V+, V-, -12V).
Same thing with the -12V pin.
Try putting back one of the regulators to detect which power line +12V or -12V has an  issue.