I had the C 3912 code appear out of the blue. It says TH3 doesn't reach temp in time. I checked the lamp and the thermo fuse and they were good. The thermistors seem to be reading temp ( I think it is just reading residual heat from the upper lamp) , but the lower lamp doesn't seem to be coming on, it stays luke warm. I tried an AC driver board , but that did no good. I have a printer control board on order. Is there anything else I should be looking at? Any advise appreciated. TIA
i think i got fooled by that code once before every thing pointed to the bottom lamp and thermisters but what it was for me was the upper lamp the three lamp bundle only 2 out of the three was comming on so if the upper fusing roller was not reaching a certin temp the bottom lamp never turned on . look very closely at the upper lamps and try to test each lamp in the bundle good luck
Answer was right on. Upper lamp had blown one filament. I have one on order. Thanx for the help. I don't know why the machine didn't show a code for the upper roller not reaching temp. It would have been a much quicker and easier fix.