Document glass original size detect problem

[oeshuron]

Sharp AR-M700n. Problem: Detecting 11x17 on document glass with no document present.

Tried: Running 41-2 adjustment -> no good; Tried replacing sensor bar with known good sensor -> no good.

Any other ideas?

[blackcat4866]

What kind of readings are you getting from 41-3 & 41-1?

41-3 will help you identify a bad sensor. 41-1 will identify a bad OCSW (that is what I suspect). Or perhaps you have extremely bright fluorescent room light throwing off your readings. As a test, turn off the room lights and review the sim 41 results.

[oeshuron]

What kind of readings are you getting from 41-3 & 41-1?

41-3 will help you identify a bad sensor. 41-1 will identify a bad OCSW (that is what I suspect). Or perhaps you have extremely bright fluorescent room light throwing off your readings. As a test, turn off the room lights and review the sim 41 results.

i dont have the machine with me right now though i can tell you the ocsw sensor was working as it woulld switch between lit and unlit when closing the adf. all other sensors remained lit regardless. i can get values from 41-3 tommorrow.

[OMD-227]

If all sensors are lit when the cover is closed, the sensors are 'detecting' an original on the glass, even though there is none. Sure, the OCSW sensor will work as it is detecting when the doc feeder is opened/closed. I think you have a faulty OCSW, as the sensors should be unlit in 41-1. That would also explain why your 41-2 adjustments failed. The machine cannot detect original size.

[Setright]

Okay, I admit I don't know how Sharp machines are wired, but I have seen similar problems on Kyocera and Konica Minolta.

What sort of switch doors the original cover use? Sometimes it's a timing thing, and the detection of originals starts too early or too late. Try putting a 1mm thick spacer on the switch actuator.

Failing that, if the machine has some sort of NV-RAM reset, try running that...but don't forget to do a data back-up first

[OMD-227]

Hey Setright,

This is not about a cover switch in this instance. In simulation, you can see if the OCSW unit is working and all size detection sensors are working within it (all with the doc feeder open). In simulation 41, you can do alot of tests & adjustments to see if the size detection is working to spec.
I get what you are saying, but the 1mm thick spacer is used more often than not with the Sharp doc feeders to lift it off the slit glass just that little bit, helping paper pass over it cleaner. It is usually fitted to the edges of the glass on each end.
I dont think a NVRAM clear would help in this case. Definitely looks like a faulty OSCW. We'll have to wait & see what Oeshuron says later.

[oeshuron]

Just got back to work and if you turn the machine on with the ADF closed, the copier acts normal with all PD sensors showing no detection. As soon as you open the ADF, all PD sensors read document detected using 41-1. When trying to do 41-2 they error with no original as I said before. This morning the PD sensors were all reading 1 using 41-3 with the ADF open but yesterday they were hovering around 12-15 IIRC.

I did mention earlier that he replaced the entire sensor unit with a known working machine unit. That is the OCSW isn't it? (I'm not the copier tech, I'll ask him). I performed a firmware update on this unit as well.

Edit: Tech switched out black little OCSW sensor to no avail. Soooo frustrating.

[blackcat4866]

Nope. The OCSW (Open Closed SWitch) is the photointerupter that tells the machine that the document feeder has been closed, and it's time to check the original size. If this photointerrupter doesn't change state the machine will never check original size. The OCSW is a button that sticks up from the main body of the machine and is pressed by the bottom of the document feeder.

Sorry I can't be more specific. It's been a few years since I've seen a Dragon.

[oeshuron]

Nope. The OCSW (Open Closed SWitch) is the photointerupter that tells the machine that the document feeder has been closed, and it's time to check the original size. If this photointerrupter doesn't change state the machine will never check original size. The OCSW is a button that sticks up from the main body of the machine and is pressed by the bottom of the document feeder.

Sorry I can't be more specific. It's been a few years since I've seen a Dragon.

Yes, the tech knew what/where it was. He replaced it with a known good one but still doesn't work. I am going to ask him about the ORSPD next.

[oeshuron]

The solution has been found. It turns out the ORSPD (document size detection light reception pwb) needed to be cleaned really well. Can't believe we missed that.

[OMD-227]

Wow... never seen that part just 'need a clean' before. It is usually the OCSW unit going bad that causes this fault.
Is the machine is a really dusty environment? If so, how are the optics?

Otherwise, nice fix!

[oeshuron]

Wow... never seen that part just 'need a clean' before. It is usually the OCSW unit going bad that causes this fault.
Is the machine is a really dusty environment? If so, how are the optics?

Otherwise, nice fix!

Machine was purchased used but didn't appear to be any dirtier than one we'd take in on trade. The tech did say he thought one of the cables came out pretty easy from the ORSPD so that might have been the main cause not 100% sure as he cleaned the sensors before reinstalling the covers. Glad we found the problem and hope this helps others in the future!