I may be way off the mark here, but here are the symptoms and my thoughts:
Symptoms: When using the document feeder for scanning or copying, the feeder will stop feeding in originals, and come to "Ready". There are still more originals in the tray. There is no jam condition or error condition. If you press start again, it will resume scanning like you just inserted some more originals. It may stop again after 5 or 50, not necessarily before they are all gone, and again come to "Ready".
Thoughts: I started out focused on the original sensor SR3. I can watch it change state in 03-Fax:ON 7C, and it does change state every time I actuate it, but I don't necessarily trust these test modes because they don't show you actual signal voltages. So I connected my meter to the DF controller CN74 pin B11 to frame ground. Most of the time I get the expected 0.02vdc actuated, and 4.99 not actuated. When the DF stopped I would get the occasional flicker of 4.99vdc, even when the flag was actuated with paper. I swapped the sensor with the identical door sensor to rule out a flukey sensor, and got the same results and no door indications, so it's not the sensor.
Then I checked the supply voltage to SR3, and this is where it gets weird. Across CN74 pins B10/B12 it starts out between 5.01 and 4.99vdc, but with the DF operating it fluctuates, bouncing as low as 4.86vdc. When I see that threshold voltage, the DF stops, even with originals. I can track this DC voltage back to DF controller CN70 pins 2/4, to the scanner logic board CN18 pin12, then to the power supply CN407 pins 2/5. The voltage rises a little along the way, but still dips below 4.90vdc on the power supply. All these connectors have been re-seated, wire ties cut, and pinned out from the DF all the way back to the PS. I'm coming back in the morning with a PS and DF controller, which seem like logical choices.
I've got a ground to neutral peak of 1.9vac at the wall. I tried two other circuits with the same result and same symptoms. And it's also possible that there's another 5vdc something that's dragging down the PS at CN407.
If I use the frame ground as reference, the 5vdc sags only 0.03vdc, and the neutral floats to 0.10vdc. I don't know if that's significant, it's just something I noticed.
Did I miss something obvious? =^..^=
Symptoms: When using the document feeder for scanning or copying, the feeder will stop feeding in originals, and come to "Ready". There are still more originals in the tray. There is no jam condition or error condition. If you press start again, it will resume scanning like you just inserted some more originals. It may stop again after 5 or 50, not necessarily before they are all gone, and again come to "Ready".
Thoughts: I started out focused on the original sensor SR3. I can watch it change state in 03-Fax:ON 7C, and it does change state every time I actuate it, but I don't necessarily trust these test modes because they don't show you actual signal voltages. So I connected my meter to the DF controller CN74 pin B11 to frame ground. Most of the time I get the expected 0.02vdc actuated, and 4.99 not actuated. When the DF stopped I would get the occasional flicker of 4.99vdc, even when the flag was actuated with paper. I swapped the sensor with the identical door sensor to rule out a flukey sensor, and got the same results and no door indications, so it's not the sensor.
Then I checked the supply voltage to SR3, and this is where it gets weird. Across CN74 pins B10/B12 it starts out between 5.01 and 4.99vdc, but with the DF operating it fluctuates, bouncing as low as 4.86vdc. When I see that threshold voltage, the DF stops, even with originals. I can track this DC voltage back to DF controller CN70 pins 2/4, to the scanner logic board CN18 pin12, then to the power supply CN407 pins 2/5. The voltage rises a little along the way, but still dips below 4.90vdc on the power supply. All these connectors have been re-seated, wire ties cut, and pinned out from the DF all the way back to the PS. I'm coming back in the morning with a PS and DF controller, which seem like logical choices.
I've got a ground to neutral peak of 1.9vac at the wall. I tried two other circuits with the same result and same symptoms. And it's also possible that there's another 5vdc something that's dragging down the PS at CN407.
If I use the frame ground as reference, the 5vdc sags only 0.03vdc, and the neutral floats to 0.10vdc. I don't know if that's significant, it's just something I noticed.
Did I miss something obvious? =^..^=
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