I've got a good one today. Have a 7530 in the field giving C-6000 codes. Changed the thermistor and power source pcb. Tech support said the zero cross signal may not be coming from the main pcb. Decided to check the main pcb in a 6330 in the shop. Lamps came on and unit dropped a C-4000 code. Is there a conflict between the 6330 and 7530 where you can't swap main pcb's? I figured it shouldn't be a problem, and I just wanted to see if this pcb was bad or if I needed a new one. Thanks

The main pcb's are different. Also the fusers are different. The main heaters, press rollers, and pressure is different.

The 7530 also has a small board on rear frame at the bottom called power source branch PCB that controls voltages to the fixing unit also. I had one once that drove me crazy trying to figure out overheating on the fuser as someone had placed a 6330 fuser into the 7530 thinking they were same. Kept warping the heat roller from so much heat. The lamps would not turn off. Replaced the board and put in correct fixing unit and all was well. The exit rollers, etc are different on the two fixing units as well. One has plastic exit roller, the other has rubber coated rollers.

Clean or replace the filters, fans above the fuser

Was able to put Main PCB in another unit and run sim 163 to clear the C-6000. For some weird reason the zero cross wouldn't clear from the original unit, but when I put the PCB back in, it worked fine.

Oh yea I forgot. Anytime you get weird codes like laser codes. Restring the MC.