I have ricoh sp c820dn printer here is message say turn power off then set the pcu correctly .cyan

Memory chip at TD sensor: Communication error

Retry of memory chip communication fails three times after the

machine has detected the memory chip communication error.

?? Damaged memory chip data

?? Disconnected inter face

?? No memory chip on the development unit

?? Noise
Replace the PCU.

Turn the machine off. Open the access door and remove the cyan photoconductor unit. Check the contact pins are straight and undamaged. Gently reinsert the unit. Turn the power back on. If the machine still does not recognise the pcu is inserted it is probably damaged and needs replacing. How many copies/prints has your machine done?

Replace the PCU.

AC charge output error [Cyan].
Poor connection with the PCU.
Check for broken connector in machine where the PCU goes into.
Defective PCU.

sc302 is usually PCU or charge roller.
As you say you have recently replaced the Drum/PCU, is the drum turning correctly?

Check charge connectors and connectors on the back of the pcu. To reset that code, simply turn main power off and on again. If problem comes right back....the machine detects the cause still exists. May be an issue with the HVT.

I THINK THE CLEANING BLADE PROBLEM, IT TORN & CAUSED THE HORIZONTAL LINE EFFECT IN THE CYAN UNIT

Perhaps, it is a faulty PCU. Try by shutting off power and using another but wait a few minutes before turning it on again.

I had the same issue with my CL3500N. I kept taking out and reinserting the color PCU with the same resulting error. However, I fixed my problem. My color PCU is now reset and printing
Instructions on how I fixed the issue:
1) Turn off the printer and remove the color PCU from the printer
2) Look inside the printer where you removed the color PCU and you will notice three attach points (gears) that each of the three color PCU rollers connect to the printer.
3) Notice that each roller inside the printer has an arrow stamped in metal pointing toward it. On my printer, one at approximately the 2 o'clock position, 9 o'clock position and 3 o'clock position.
4) On the color PCU look at the end of unit that you insert into the printer. Notice the white female connectors on each of three rollers. Look closely and you will see that there are notches inside each connector (gears). One of those notches is longer than the others.
5) For each roller insert your finger into the white connector (gear) to rotate the roller so the long notch aligns with the arrow inside the printer. Be careful not to touch the photo sensitive area of the roller.
6) Insert the color PCU into the printer and turn it on. May need trial and error to align the notch correctly, but it certainly worked for me.

Hello sir; The procedure little bit difficult, Remove PCU, remove the front cover(two screws), remove the rear bushing by remove one lock ring, remove the front joint, remove the developer hopper cover( 3 hook ) dump the old one out vacuum entire unit ( magnet roller ), fill in new developer, replace hopper cover, after replace PCU and developer you need to do some simulation, #1, press "clear mode" "107" and press hold "clear/stop" for 3 seconds, then touch screen on "copier sp". #2, enter sp3902-9 to1 for black drum unit, sp 3902-10 to 1 for yellow, sp3902-11 to 1 for cyan, sp3902-12 to 1 for magenta, #3, enter 3902-005 for black, 3902-006 for yellow, 3902-007 for cyan, 3902-008 for magenta, set 3902 to 1 for each of these if replaceing developer, press "exit" twice to end the service.

cyan problem --check if cyan pcu is set properly or replace cuan pcu(drum)