20 Most Recent Ricoh Aficio SP C420DN Laser Printer Questions & Answers

You just have a problem with colour PCU (SC 365 - magenta, SC366 - cyan). The main reason is that toner density is abnormal. Sometimes, when you replace toners, printer receive to much toner for a short time, and after that you have an abnormal toner density (higher). You can check in service mode (hold up and down arrows for 6-7 sec, release them and press ok button) following thing : choose 2. engine then with arrows choose 3. process then choose Vt display, for each color by default there should by somewhere arround 2.4V. If you see for some colors, for example 0.02V, then this is a problem(to much toner). In this case the only thing that you can do is to restart printer and try to print enough pages, filled with problem color. Usually you can print max 3 pages. Then restart printer and try another 3 pages. Print until the you will be able to print at least 4 pages continuously. Good luck and remember that this is a technical problem and you should ask someone qualified for the job. I am sure that 80% of service engineers can't repair this issue. But I can.

Open left printer cover. Open PCU cover. Pull Magenta, Yellow and Cyan PCU units and check which one has blocked!!! Probably you will need to replace color PCU (type 145). Good luck

Probably you have just replace some of the toners (black). The toner density is too high. Restart printer and try to print full A4 black page.

SC362 is a Cyan TD sensor high error.TD sensor defective. Replace PCU.

have you tried cleaning the charging wire and the transfer belt

In an SPC420 color printer the issue is that the PCU is not turning for one of the colors. The sprockets that drive each of the color PCU's should be checked. Sometimes they stick and need lubrication. With the printer off, remove all the PCU's and look at the black, plastic sprockets that turn the color PCUs. See if one is recessed and unable to slide forward like the others. Place some oil on the sprocket and use the needle nose pliers and push the sprocket in and out until it slides without catching on the rod it is mounted on. Like a dentist trying to pull a tooth.