MZ790U Error T02-401 (over current in the elevator motor)

[dearjessica]

Yesterday my MZ790U machine started to flash error # T02-401 that could not be cleared with the RESET key / my machine will not print at all.

Full disclosure: about 3 months ago the machine began flashing T02-401 whenever the paper feed tray was empty. It could be cleared easily by putting some paper in the feed tray and pressing Reset. Since then the machine has been running 90% smoothly using the same fix over and over. The only thing was the little green button on the paper feed no longer responded when the paper feed was completely down. It did work, however, when it was at any other position and you needed the feed tray to go down.


But now I'm not sure what to do as I've troubleshooted by turning the machine on and off, removing paper, making sure nothing is blocking or touching the tray, gently opening and closing the input tray, etc. Nothing I seem to do externally helps so I think I am in need of a technician.. but I live in Oslo, Norway.

Any advice, diagnoses, offers to sell parts, etc are all welcomed! Thank you.

[Iowatech]

Re: MZ790U Error T02-401 (over current in the elevator motor)

I don't have my manuals on me right now, but here's a suggestion you might try.
Check the elevator lower safety switch actuator, I think it is a metal plate under the paper tray that pivots a little bit. I've seen those get bent just a little bit on RZ's at least, and that can cause intermittent or prolonged problems with elevator movement. If it is the same on MZs, make sure that plate moves up and down.

[dearjessica]

Re: MZ790U Error T02-401 (over current in the elevator motor)

Hi, thanks for the tip! Unfortunately I'm not sure that's the problem. The elevator lower safety switch on my machine does have a tiny dent, but it moves up and down (and even a bit left to right) with no problem.What happens when the error appears is you hear a sound like the elevator wanting to start (or maybe just the drum rotating in anticipation of printing?) and then a tiny beep. The elevator doesn't move at all and the green button on the upper safety is not lit up. When you press it in this also causes the error..

I don't have my manuals on me right now, but here's a suggestion you might try.Check the elevator lower safety switch actuator, I think it is a metal plate under the paper tray that pivots a little bit. I've seen those get bent just a little bit on RZ's at least, and that can cause intermittent or prolonged problems with elevator movement. If it is the same on MZs, make sure that plate moves up and down.

[jermyth]

Re: MZ790U Error T02-401 (over current in the elevator motor)

Do you have a service manual? I wonder if the elevator motor assb'y is shot or something is in the way of the paper tray gears. How handy are you with a screw driver?

[dearjessica]

Re: MZ790U Error T02-401 (over current in the elevator motor)

Do you have a service manual? I wonder if the elevator motor assb'y is shot or something is in the way of the paper tray gears. How handy are you with a screw driver?

Hi, I don't have a service manual but I have the parts manual with all the technical diagrams..

Today I used a screwdriver to remove all the plastic panels on the side of the Riso with the paper feed and tried using canned air to clean out any sensors that might have been blocked on the inside. Unfortunately, that didn't seem to do anything. But these are the test results I got for running all the Paper Feed Tests in TEST MODE (maybe this can help reveal something?):

600S Paper Detection Sensor - ON
601S Paper Size Detection Sensor - OFF
602S Elevator Upper Limit SensorA - OFF
603S Elevator Upper Limit SensorB - OFF
604S Elevator Lower Limit Sensor - OFF
605S Paper Feed Sensor - OFF
606S Paper Ejection Sensor - OFF
607S Upper Safety Sensor SW - ON
608S Lower Safety Sensor SW - ON
609S Feed Tray Button - OFF
610S Paper Volume Det. Sensor A - OFF
611S Paper Volume Det. Sensor B - OFF
612S Paper Ejection FG Sensor - OFF
614S Paper Feed Pressure Sensor - OFF
615S Registration Sensor - OFF
616S Guide Roller Release Home Sensor - ON
617S Mid-Feed Sensor - OFF
618S Paper Ejection Wing Home Sensor - OFF
619S 2nd Feed Motor Limit - OFF
620S Mid-Flap Home Sensor - OFF

660M Paper Ejection Motor - In Action (Normal)
661M Suction Fan - In Action (Normal)
662M Separation Fan - In Action (Normal) 663M 2nd Feed Motor - In Action (Normal)
668M Feed Tray Buttom LED - In Action (Normal)
681U Paper Feed Tray Max. Positioning - ERROR T02-401
682U Elevator Motor Action - ERROR T02-401
683U Elevator Motor Action (down)- ERROR T02-401
684U Separation Pump Solenoid - In Action (Normal)
685U Paper Feed Solenoid - In Action (Normal)

... all those in between are In Action (Normal)

705U Multi-Paper Feed Auto Adjust - "In Action" ** running this test freezes this machine **
708U Elevator Motor Action (up) - "In Action" for about 20 seconds.. then flashes ERROR T02-401
709U Registration Sensor Auto Adjust - ERROR T98-448

... all those after are In Action (Normal)

I'm the most baffled by this because I don't see anything blocking anything (but maybe I'm not looking in the right places) and it was running just fine days before. Totally out of the blue this problem.

[20gaugeO/U]

Re: MZ790U Error T02-401 (over current in the elevator motor)

Is the feed tray all the way down, all the way up, or somewhere in between right now? How many copies on this machine?

Meter the wires that run to the elevator motor (RP's used to break). Unplug the elevator motor and rerun the test modes that would cause the T02-401. If it codes differently then it probably is the motor assy like jermyth said.

[dearjessica]

Re: MZ790U Error T02-401 (over current in the elevator motor)

Is the feed tray all the way down, all the way up, or somewhere in between right now? How many copies on this machine?

Meter the wires that run to the elevator motor (RP's used to break). Unplug the elevator motor and rerun the test modes that would cause the T02-401. If it codes differently then it probably is the motor assy like jermyth said.

The feed tray is all the way down and the last time it was functioning properly (and the first time it didnt work for that matter) there were no strange sounds. The machine also has approximately 2 million copies.

As for unplugging the elevator motor, I'm a bit nervous to do it but I'll either do it tomorrow or try to get our one local tech to try. I called him Monday and learned no one in Norway has serviced a Riso in years.. so he sounded both hesitant and possibly up for the challenge to fix my machine.

Finally, if it is the elevator assembly like you all say that's not working properly--is this an easy part to replace / obtain?

Thanks so much for all your help!

[jermyth]

Re: MZ790U Error T02-401 (over current in the elevator motor)

It is not that difficult to remover & replace the elevator motor unit. Remove the front cover, 8 screws. Remove the front spring. unplug the connector & unscrew the ground wire. Detach the e-ring. Hold the paper feed tray while removing the unit. You can replace the whole unit, suggested, or open it to see if you got a broken gear in it. When reinstalling the unit make sure you get the tray level. Its very easy to be off a tooth or two on the track and then youll have a crooked tray. Private message me if need the Elevator unit, I might be able to help. Good luck.

[20gaugeO/U]

Re: MZ790U Error T02-401 (over current in the elevator motor)

If you remove the rear spring also the table won't try and raise. It's the same setup that they used on the RP's. Broken gears or broken wire is what you'll probably find. You've come this far.
Good Luck

[dearjessica]

Re: MZ790U Error T02-401 (over current in the elevator motor)

Thank you jermyth + 20gaugeO / U for the encouragement and help!

My PM is being weird and showing messages in but not those I sent. If you both didn't receive any from me, my email is dearjessica@gmail.com

[dearjessica]

Re: MZ790U Error T02-401 (over current in the elevator motor)

Surprise update! The Riso is back up and running.

Almost perfectly..

I did as you both recommended and cleaned / inspected / disconnected the elevator motor. Nothing seemed to be superficially broken or missing so I initially felt at a loss. I then reran the tests where I previously received T02-401 errors:

708U Elevator Motor Action (up) - "In Action" for about 20 seconds.. then "Done". No sounds, kind of mysterious.

681U Paper Feed Tray Max. Positioning - ERROR T02-405
682U Elevator Motor Action - ERROR T02-405
683U Elevator Motor Action (down)- ERROR T02-405

A new error seemed positive but it obviously still wasn't working (the motor wasn't connected) so I gave a big sigh and turned the machine off. Just so I wouldn't forget where all the screws went, I reconnected everything and turned the machine on one more time just to see if the T02-401 was back. Surprisingly, it wasn't! And the machine did a run of 50 test prints (and a master making) just fine.

However, as soon as the paper is empty the T02-401 pops up again. But it is now easily cleared by loading more paper and pressing RESET. Any insight?

Finally, apologies to jermyth. I think I've sent you way too many PMs on accident! My computer is still broken so I'm writing on an iPad.

[20gaugeO/U]

Re: MZ790U Error T02-401 (over current in the elevator motor)

It shouldn't code every time it runs out of paper.
I think you moved a wire that is broken (and made better contact) or the motor is on the verge of total failure. Did you open up the black motor assy? You just have to be careful that you know where the gears go in there. The elevator motor assy is sold as a unit. IMHO replace the motor assy and wire harness and I think your problem will be fixed.

[dearjessica]

Re: MZ790U Error T02-401 (over current in the elevator motor)

Good Point. It should not be doing this at all.

I did open up the black assembly when I unplugged the motor. I was wary of the gears so I didn't mess with them too much.

Thanks for your help (the diagrams especially) and I will look into replacing these both ASAP!

It shouldn't code every time it runs out of paper.
I think you moved a wire that is broken (and made better contact) or the motor is on the verge of total failure. Did you open up the black motor assy? You just have to be careful that you know where the gears go in there. The elevator motor assy is sold as a unit. IMHO replace the motor assy and wire harness and I think your problem will be fixed.

[dearjessica]

Re: MZ790U Error T02-401 (over current in the elevator motor)

Hi again!

Some good and bad news:

Finally today I received new replacement parts in the mail (both elevator motor and wire assembly) from RisoCenter in the Netherlands.

The good news is that they were easily installed. The bad news is that my problem is still not fixed! Well, the machine works fine, except that I still get that pesky T02-401 error every time the paper feed is empty. I also can trigger the same error by pressing the green round button on the paper tray (when the tray is down, not when it is up).

So mysterious.. does anyone have any second opinions?

[20gaugeO/U]

Re: MZ790U Error T02-401 (over current in the elevator motor)

If it was me I'd start cutting cable ties dealing with the feed table and front end area. Moving the wires around and putting only needed cable ties back on loosely (sometimes they pull them way to tight). Look for a pinched or broken wire by stressing it.

The latest firmware for this machine is version 4.22, with a handful of upgrades from v 3.16. You'd have to have a compact flash card also to upgrade it. The one I use is 128MB.