HP LaserJet Pro 300 Service Manual - Page 100

DC controller PCA Special considerations WARNING! Do not install a replacement formatter PCA and a replacement DC controller PCA at the same time. The formatter PCA and the DC controller PCA store important product configuration information (NVRAM data) that is lost if both PCAs are replaced at the same time. When the product power is turned on, the formatter restores the NVRAM data to a replacement DC controller. Replacing both the DC controller and the formatter at the same time will result in severe print-quality problems. Replacing the DC controller PCA before the formatter PCA Use the following procedure if you need to install a replacement DC controller and a replacement formatter PCA. NOTE: If you are only installing a replacement DC controller PCA, go to Remove the DC controller PCA on page 76. 1. Install a replacement DC controller PCA. 2. Turn the product on, and wait for the print-cartridge volume indicators to appear on the control- panel display. NOTE: This allows important product information to be written to the replacement DC controller PCA. 3. Turn the product off. 4. Install a replacement formatter PCA. See Formatter PCA on page 74. 5. Turn the product on. Remove the DC controller PCA Before proceeding, remove the following components: ● Right cover. See Right cover on page 21. ● Upper cover. See Upper-cover assembly on page 41. ● Right panel. See Right panel on page 52. 76 Chapter 1 Removal and replacement ENWW