FS-539, completely dead, or is it? Interesting experience today.

[femaster]

Had an interesting bit of troubleshooting today. Maybe this will help out someone else down the road with a similar issue.

One of our techs swapped out an FS-539 on a C360i yesterday. Every symptom pointed to a finisher that was completely dead. The LED on the board in the finisher would not light, copier did not know the finisher was even attached. A check of all fuses on the board tested OK. If you just want the solution, jump to the last paragraph...

It was brought back to the office for troubleshooting. I was sure that it was going to be a dead board that I would need to send in for warranty replacement. Ended up spending a total of close to 2 hours trying to figure out what the problem was. I tried the board with all wire harnesses disconnected except the harness coming from the copier. Miraculously the copier saw the "finisher" at that point and the LED on the board was blinking. I installed the board in a known good finisher, and it functioned perfectly.

Put the board back into the original finisher, same as before, acted completely dead. Removed one wire harness at a time from the board until I found the culprit. It was the harness connecting to socket J4. There are 3 motors, 5 Photo Sensors, and one LED (from the manual stapler). Disconnected everything on the other end of the harness and connected one at a time. Eventually found the problem child. I fully expected it to be a motor, but it turned out to be the entrance sensor (PS4). Disconnecting the harness on the side of the finisher (under front cover) and the finisher fired up perfectly.

Found that the short 8" piece of wire harness that connects from the side of the finisher to the entrance sensor was pinched from the factory and shorting out on the metal plate on the entrance to the finisher. That shorted wire took out the entire finisher and made it act like it was completely dead.

[tsbservice]

I should say - I'm not wondered why you're service manager

[blackcat4866]

Nice work, systematically moving towards the culprit. Dead shorts like this can be difficult to find, and occur anywhere in the machine.

Your method is the quickest way there:
Disconnect everything but the harness to the machine.
Do you see the finisher? Great!
One by one, reconnect each harness until you don't see the finisher.

The real mind-benders are the ones that resume working when you plug everything back in. In cases like that I just scratch my head, and am grateful that it's working again. =^..^=

[kingarthur]

Had an interesting bit of troubleshooting today. Maybe this will help out someone else down the road with a similar issue.

One of our techs swapped out an FS-539 on a C360i yesterday. Every symptom pointed to a finisher that was completely dead. The LED on the board in the finisher would not light, copier did not know the finisher was even attached. A check of all fuses on the board tested OK. If you just want the solution, jump to the last paragraph...

It was brought back to the office for troubleshooting. I was sure that it was going to be a dead board that I would need to send in for warranty replacement. Ended up spending a total of close to 2 hours trying to figure out what the problem was. I tried the board with all wire harnesses disconnected except the harness coming from the copier. Miraculously the copier saw the "finisher" at that point and the LED on the board was blinking. I installed the board in a known good finisher, and it functioned perfectly.

Put the board back into the original finisher, same as before, acted completely dead. Removed one wire harness at a time from the board until I found the culprit. It was the harness connecting to socket J4. There are 3 motors, 5 Photo Sensors, and one LED (from the manual stapler). Disconnected everything on the other end of the harness and connected one at a time. Eventually found the problem child. I fully expected it to be a motor, but it turned out to be the entrance sensor (PS4). Disconnecting the harness on the side of the finisher (under front cover) and the finisher fired up perfectly.

Found that the short 8" piece of wire harness that connects from the side of the finisher to the entrance sensor was pinched from the factory and shorting out on the metal plate on the entrance to the finisher. That shorted wire took out the entire finisher and made it act like it was completely dead.

Don't you just love the "pinched cable". had a C364e a few years back, had an intermittent problem with the paper feed on tray 2, took over 8 hours to track down a pinched cable...had to cut all the cable ties going from the actual unit to the PCB, and then had to test each cable one by one.

Well done to you for tracking it down .