Ricoh MP C4503 + SR3160 – Error SC720-71 after shift tray movement

[Peter Zeravla]

Hi everyone,

I’m using a Ricoh MP C4503 with a SR3160 finisher, and I’m getting the error SC720-71 at startup.

Here’s what happens:

• When the machine starts, it makes a bit of noise while the shift tray is moving up.
• Right after that, the SC720-71 error appears.
• I’ve noticed that the stapler mechanism seems to be moving in a strange way, but I’m not completely sure it’s the cause.

Some things I’ve tried:

• I released the belt/cord that drives the right-side gears (where the door is located).
• I also released the shift tray, and it seems to sit correctly on both sides.
• When I manually rotate the motor (with the machine off), everything appears to move smoothly — no apparent blockage or misalignment.

---

My questions:

1. What is the "home position" for the shift tray?
   Since I moved it manually while testing, I’m not sure if it's still correctly aligned.
2. Is there a way to test the tray movement sensors (those that check the tray position/timing on one side) to confirm if they are working correctly?
3. In your experience, is it more likely to be a sensor issue or a motor problem for this type of SC720-71 error?

Any suggestions or steps to troubleshoot this would be greatly appreciated!

Thanks in advance for your help.

[slimslob]

It does not have to do with the "shit tray"That would be the shift tray motor. It is the motor that shift the sheets forward or back just before they exit for sorting. If you have the full service manual that includes information on the peripherals, Section 1.26 SHIFT MOTOR of the booklet finisher portion. The motor is either bad or in a bind.

[Peter Zeravla]

It does not have to do with the "shit tray"That would be the shift tray motor. It is the motor that shift the sheets forward or back just before they exit for sorting. If you have the full service manual that includes information on the peripherals, Section 1.26 SHIFT MOTOR of the booklet finisher portion. The motor is either bad or in a bind.

Thanks again for your reply — it helped confirm what I had already read before.

I had actually seen before that the SC720-71 error is related to the shift motor (the one that moves the sheets forward/backward for sorting), but since I noticed the shift tray making an unusual noise when moving up, I thought maybe that part was involved too.

So I decided to disassemble and check the tray mechanism just in case.
But after putting it back together, it started making a loud noise when lifting the tray, like the gears weren’t engaging properly — so I had to power the machine off quickly.

Now I feel I may have created a new issue while trying to investigate the original one. 😅

Do you know if there’s any video or detailed step-by-step guide showing how to properly access the shift motor on the SR3160 finisher?
I’d really appreciate that, as I want to avoid making the same mistake again.

Thanks again for your help — your message gave me the confidence to focus on the real cause.

[slimslob]

From the service manual:
1.26 SHIFT MOTOR
1. Rear cover ( page 3)
2. Shift motor [A] ( ×2)
image.png

[Peter Zeravla]

From the service manual:
1.26 SHIFT MOTOR
1. Rear cover ( page 3)
2. Shift motor [A] ( ×2)
image.png

Thanks! Yes, I did see that image in the manual — but I couldn’t quite locate that part on the actual finisher when I opened it.
Maybe I missed something; I’ll take another look in the next few days when I get back to it.

By the way, after I reassembled the shift tray, the machine started making a loud noise when lifting the tray — it sounds like the gears aren’t meshing properly or maybe the motor is struggling.
Any idea what could cause that kind of noise? Could it be something misaligned when reinstalling the tray, or maybe a timing issue?

Thanks again for your time and help — it’s been really useful so far.

[luca72]

Hi everyone,

I’m using a Ricoh MP C4503 with a SR3160 finisher, and I’m getting the error SC720-71 at startup.

Here’s what happens:

• When the machine starts, it makes a bit of noise while the shift tray is moving up.
• Right after that, the SC720-71 error appears.
• I’ve noticed that the stapler mechanism seems to be moving in a strange way, but I’m not completely sure it’s the cause.

Some things I’ve tried:

• I released the belt/cord that drives the right-side gears (where the door is located).
• I also released the shift tray, and it seems to sit correctly on both sides.
• When I manually rotate the motor (with the machine off), everything appears to move smoothly — no apparent blockage or misalignment.

---

My questions:

1. What is the "home position" for the shift tray?
   Since I moved it manually while testing, I’m not sure if it's still correctly aligned.
2. Is there a way to test the tray movement sensors (those that check the tray position/timing on one side) to confirm if they are working correctly?
3. In your experience, is it more likely to be a sensor issue or a motor problem for this type of SC720-71 error?

Any suggestions or steps to troubleshoot this would be greatly appreciated!

Thanks in advance for your help.

try to restore the initial situation (sc720-71) and then give a good blow with the compressor (from the inside) on the hp sensors near the short worm screw of the jogger unit
while you're at it blow them all

[Peter Zeravla]

Ok, as soon as I’m able to work on it again, I’ll check your suggestions. For now, I’m just gathering all the information I can.