Ink sweep stuck at 100%

Hi Guys,

Our press has developed a problem over the last 2-3 days.

After imaging or when manually entering ink values the motor which controls the ink fountain roller sweep moves worm gear all the way until the mechanism behind the bell housing touches against the roll pin and can move no further.

If I try set the sweep to 0% or 100% it always moves in the same direction full open until it cannot move any further, this seems to be happening on all printing units and the fault occurred on all of them at the same time.

If anyone has seen this problem before we would greatly appreciate some insight.

Thanks
Andy

 

It is possible the potentiometer has failed on the unit, swap a potentiometer from another unit and see if the problem goes away.

 

Hi Paul,

Thanks for the reply, the problem is happening on all units. The motor driving the worm gear moves until it hits the stop and cannot move further.

So all the ink fountain rollers are sweeping at their maximum capacity all the time.

We tried reinstalling the presses footprint however this didn't help

Andy

 

Hi Guys,

We've had no luck sorting out our problem, I'll try describing it abit better and I've also uploaded a video of the problem (sorry about the focus this was taken on a camera phone).

No matter what value we enter on the screen the motor always turns to the maximum open position. (in the video the sweep was set to 17%)

[video=youtube;eQokagBFpYA]http://www.youtube.com/watch?v=eQokagBFpYA[/video]

 

The way this system works is like this:

1. You enter a value in the GUI/ PC.
2. The TSK board recognizes the request to change.
3. The TSK relays this information to the MOT board which tells the motors to start moving (Ink keys and Fountain motors).
4. The MWE sees the motors moving and starts reading the position of the potentiometers. It realys this information back to the TSK.
5. The TSK compares the position of the ink key / fountain to the newly inputted value. When they match it tells the MOT board to stop moving the motors.

Out of curiosity I would loosen the worm gear and move it away from the adjustment gear so the worm gear can spin freely on one unit. (3rd) Make an ink fountain change and see if that motor moves and then stops. Make it go from 0 to 100. It should work normally. If it does, then somehow all of your worm gears lost their positions and now your adjustment gear is bottoming out on the stop bolt when you try to increase the values.

It is an easy fix if this is the problem. Just move all the worm gears off the adjustment gears. Set them all to zero and let them move until they stop. Manually adjust the adjustment gear to the zero position and move all the worm gears back until they engage with the adjustment gear.

If they all bottom out to 100 again you may have an issue with the MWE board.

 

Hi Paul,

Thanks for your reply I will try moving the worm gear away tomorrow morning.

I forgot 2 details which may help pinpoint the problem the motor turns even when we are not setting values in the GUI
(i switched the press off and turned the motor screw until the sweep was at about 50% but after running afew hundred sheets the motor had moved it back to the max position)

and to my knowledge the motor will only turn 1 direction if I try lower the sweep it still increases it to maximum.

I will try what you suggested tomorrow thanks again Paul.

Andy

 

Hi Andy, never have had TSK, MOT or MWE broken till now, but it's in your case one of them for sure.
If it would be only in one unit, you could look for broken potentiometer on the motor or bad contacts, but when all 4 motors are running like crazy against the pin, it is the electronic board(s) most probably MWE.
rgds
Jan

 

Hi Jan, sorry about my late reply. We were extremely busy during december and only getting back on a computer now.

Before I noticed the problem we removed the cover off the blank in fountain to adjust ink keys. Is it possible something was nipped putting the cover back on?

Can I remove the 2x wires going to Ink keys / Sweep motor off PU1 and test this or do all printing unites have to be connected at the same time?

If a board is gone what is the best way to diagnose which one?

 

Normally !!! you are not able to make something wrong putting the cover back, the wires are good protected.
You can do all test you want, the worse that could happen is the frozen GUI screen and need to restart your PC.
Check first if you have all 5 pcs. GND blue cable connected to the MAR4 back plane, check all potentiometer and motor signal the best directly on LUM 10 small board (for you will be easier directly on each single unit).
No way to check which board is broken (besides you see any damages, burn outs ), the best way is to have them all and to check one by one.
Jan

 

Hi Guys,

Just wanted to update this thread as we have been working around our problems up until today.

We purchased a second QMDI and we were able to remove the MWE board as suggested by Paul & Jan for testing in the new press this instantly resolved our problem.

We then studied the original MWE board and found 2x burnt resistors and a burnt capacitor. We were able to replace these components and the board is now fully functional again.

Thanks again for all your help allowing us to get to the bottom of this problem.
Andy