Just picked up an MP C3500 to re-sell
The DF plug connector to the machine was pooched, so I put on another one, but I may have made a bad mistake, because it was a slightly different one, (off a 2035 machine). It is almost identical except the 2 connectors for the DF mainboard are wired slightly differently, and I didn't notice (sort of in reverse)
On power-up I got an SC144 - 02, found that Fuse 10 on PSU had blown, replaced it, and the harness, and now I have no codes but the DF doesn't do anything. I can't be sure it worked previously either, but I have never had an issue like this before, so I have to think it was fine.
I have now replaced the DF with a known working unit, the connector/joiner that joins the DF harness to the machine, and also the SIO:PCB with no luck.
The DF does respond to open covers, and when I check outputs, I can engage the Main motor, and paper size sensors, clutches, (I'm not sure what else I checked), but the feed in motor won't turn on, and it doesn't acknowledge the switches when paper is set.
It got late and very frustrating, so I had to give up for the night. But I'm hoping I can get back at it tomorrow with some fresh ideas.
If anyone runs across an unresponsive DF3010, it turns out it may be caused by a blown fuse 4 on the PSU.
I swapped in a new PSU and that solved my problem, and then tracked it down to Fuse 4 causing the issue, even though No SC codes or otherwise were displayed
My stupid mistake cost me several hours, but not much 'real' money, and I learned some things, so it's not all bad.