Hello,
Registered here to resurrect this excellent thread and share my findings. I am locked in battle with a Samsung CLP-670N which is exhibiting the same symptons: multiple blank pages being fed followed by internal paper jam every time it prints. I agree with previous posters who suspect it's caused by a failed sensor,
but which one? As it happens the "service manual" (worst excuse of one I've ever seen) lists a number of sensor tests in the "tech mode", though the only three sensors I have been able to locate physically all test good. It took me a while to figure out how these sensor tests work; at first they seemed to do nothing and the display was stuck on NNNN-"sensor name" Status: [Low] no matter how I wiggled the sensor interruptor - it turns out you need to press the "Ok" button to start the test, after which the status will alternate between [Low] and [High] as the sensor is de/activated. Here's an example of me toggling the "exit sensor":
The documentation for this printer is a mess though, and I have been unable to identify any sensors beyond these three:
4) Paper Empty Sensor / 2) PAPER_EMPTY (0010 Tray1 Empty in test menu, NSENS_CST_EMPT on PCB)
6) Paper Feed Sensor (SCF 1) / 3) SENS_FEED (0290 Feed Sensor in test menu, NSENS_FEED on PCB)
3) Exit Sensor / 5) SENS_PAPER_EXIT (0370 Exit Sens in test menu, NSENS_EXIT on PCB)
How they managed to end up with no less that
four different references for each sensor is beyond me, but it's an impressive feat for sure - if you want to create maximum confusion. However, the illustrations in the "service manual" lists many more sensors, and I'm particularly suspicious of the one called
2) Regi Sensor / 4) SENS_REGI (not present in test menu AFICT, connection not located on PCB)
Despite the poor documentation I'm quite fond of this printer - when it was working it produced great quality prints, and it's only done 16k pages out of a life expectancy of 200k. I also have a full set of BNIB toner cartridges for it in addition to the installed ones (which have plenty of life left). In other words, it would be nice to get it back in action! Curious to hear if any of the contributors to this thread got any further with theirs?