Xerox 7428 - Error 077-903

[monot595]

We've had this intermittent problem for a while and I dont want to throw the machine out as its been a good little runner but it consistently jams when we print on SRA3, other paper sizes it seems OK.
When printing the 1st side of a simplex or duplex job, the machine jams with 1/4 of the sheet poking out to the delivery tray.
Clearly this is something to do with a sensor, and correct me if I am wrong the code 077-903 relates to "077-903 - indicates that paper was detected at the registration sensor before it was expected"
But I cannot for the life of me see where any sensor might be in the fusing delivery area or even if I did what to do other than clean it and check wiring?
Anyone know where the registration sensor is? and or where I can get a service manual for this machine so that I can investigate myself?
Any help appreciated.

[Phil B.]

We've had this intermittent problem for a while and I dont want to throw the machine out as its been a good little runner but it consistently jams when we print on SRA3, other paper sizes it seems OK.
When printing the 1st side of a simplex or duplex job, the machine jams with 1/4 of the sheet poking out to the delivery tray.
Clearly this is something to do with a sensor, and correct me if I am wrong the code 077-903 relates to "077-903 - indicates that paper was detected at the registration sensor before it was expected"
But I cannot for the life of me see where any sensor might be in the fusing delivery area or even if I did what to do other than clean it and check wiring?
Anyone know where the registration sensor is? and or where I can get a service manual for this machine so that I can investigate myself?
Any help appreciated.

1 are all paper trays set in machine properly?
2 is it from one tray only?
3 copy/print ..both?

INFO

[adriansto]

77-903 mean POB Sensor static jam.
This sensor is in the midlle of the left hand cover assy just upper than 2nd BTR.
But if you say other papers size goes then probably the sensor is ok.
You need to check for some obstructions in paper path or some shafts with rollers have problem, entrance in fuser dirty, something who slowdown the speed of paper when you use sra3 size paper.
Or even misguiding of papar from registration chute/rollers.
Probably you need to disassembly the left hand cover assy

[monot595]

1 are all paper trays set in machine properly?
2 is it from one tray only?
3 copy/print ..both?

INFO

Yes all paper trays are set properly and it doesn't matter which tray we feed from.
We only use the machine to print from so haven't actually tried the copy feature...I'll give it a go see if it makes a difference

[monot595]

77-903 mean POB Sensor static jam.
This sensor is in the midlle of the left hand cover assy just upper than 2nd BTR.
But if you say other papers size goes then probably the sensor is ok.
You need to check for some obstructions in paper path or some shafts with rollers have problem, entrance in fuser dirty, something who slowdown the speed of paper when you use sra3 size paper.
Or even misguiding of papar from registration chute/rollers.
Probably you need to disassembly the left hand cover assy

Thanks for ID'ing the sensor I know where it is now
Ive checked the paper path for obstruction and all seems OK -Will blow through assembly with airline see if that helps and also check the rollers more thoroughly
Thanks