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Trouble-Shooting The Mailbox Units Of The LJ 8000 Printers

18 Feb, 2001 By: Steve Geishirt imageSource

Trouble-Shooting The Mailbox Units Of The LJ 8000 Printers

Last month, we looked at the trouble-shooting tools of the sheet feeders for the 8000 version of printers. As I stated in that article, this month’s text will focus on the Multi-bin Mailbox units, or MBM’s, and their independent internal tests.

I think it is important to show the same chart as last month displaying what external paper handling units, work with what printer. I also feel it is important to reiterate that the 5Si’s optional accessories, no longer in production, are replaced by the 8000’s version, where compatible. The older 5Si accessories should not be used on the 8000’s version of printers. The 5Si versions of accessories do not have these diagnostic capabilities.

Diagnostic For The 5 And 8 Bin

We’ll start with diagnostics for the 5 bin and 8 bin mailbox units; both units have the same test. To run the diagnostic on either the 5 bin or 8 bin units, it is best to disconnect the MBM completely from the printer so it is easy to move around giving you full view of the working components of the unit. Next, locate the switch on the side of the power supply to put the unit into test mode, see Figure 2. With the power cord disconnected from the MBM power supply, set the switch on the power supply to test mode. Next, plug in the power supply and depress the interlock switch, Figure 3. Wait for a second and the head assembly will begin to move up and down twice, stopping at the bottom bin. The paper path motor will still be running and the unit will now take paper. A single sheet can be feed into the area that normally takes paper from the printer. The paper will be pulled into the flipper area of the MBM; this will shoot the paper out towards the top tray and then pull it back in again, flipping the paper over. The purpose of this is to get all the sheets facing in the correct numeric order, page 1, 2, 3, 4… (in duplex) as opposed to 2, 1, 4, 3…(in duplex). Once the paper has been flipped, paper is diverted down a belt to the head assembly, which deposits the paper into the bottom bin.

This is the only self-test the 8 bin and 5 bin with stapler can do. It does utilize the majority of the functions of these MBM’s, the exceptions being the stapler unit and depositing paper into the other bins. For what you do have running in this test, you can easily see the majority of the paper path and identify areas that are intermittently malfunctioning or catching paper.

Unit Not Running

What if the unit does not run? How do we determine what is malfunctioning with the unit? Like the sheet feeders, the MBM’s have a status LED, plus a set of three LED’s to provide error codes. The green LED at the top of the unit is the status LED, which can be seen through the outside front cover. This is the same status light that is seen when the unit is working with a printer. When the status light turns red, the LED’s on the other side of the unit will display a code to tell you what it found. These LED’s can be seen through the rear cover of the MBM. The meanings of the LED error codes are found in the 8000, 8100 or 8500 service manuals and not on the inside cover of the MBM, unlike the HCI units of the previous article. In other words, you need the service manual to understand the meaning of the error codes or you may not know what is wrong with the unit.

The 7 Bin

While the 5 and 8 bin MBM’s basically run but one test, the 7 bin unit is very different. It is different not only in the tests it can perform, but different also in the way it diverts paper into the bins. The 7 bin unit does not have a head assembly that runs up and down the unit to deliver paper into each bin. Instead, it has a flipper at each bin and two solenoids that flip a set of three or four flippers at a time. Paper is timed so the leading edge has passed the higher tray and one solenoid activates to divert the paper into the correct tray.

There are paper detection sensors in the paper path and each tray to verify that the paper went where it was supposed to. The advantage of this is no more moving head assembly, which tends to be one of the most common failures of the MBM units. Thus, the 7 bin table top mailbox tends to be more reliable than the 5 or 8 bin units.

Testing The 7 Bin

To run the tests on the 7 bin unit, remove the rear cover, 2 screws as shown in figure 4. Then using your fingers, pry the cover out in the three spots also pointed out in figure 5. These three spots have plastic clips that need to be unclipped. The instructions for the tests are located inside the cover you just removed. Figure 6 shows the PCA’s inside the cover with arrows pointing to the blue power supply switch, which is pulled out to run a test. The DIP switches are located at the top of the green PCA , and the interlock is the black button on the bottom.

There are 4 tests that can be run on the 7 bin unit with it detached from the printer. These tests include: the Motor Test, Standalone Running Test in Mailbox Mode, Standalone Running Test in Stacker Mode, and Sensor Test.

Sensor Test

We’ll start with the sensor test by first setting the DIP switches to the proper setting, then pulling out the blue lever and depress the black interlock switch. You should hear the main motor kick in followed by a double thump, sound. The thump sound is the actuation of the solenoids that divert the paper into the bins. Depicted in figure 8 are the reversing gears that first push the paper out into the top bin and then pull it back in (flipping over the paper like before) to deliver it to a lower bin. If nothing happened at the start of the test, there may be paper in the path or one of the paper access doors might be open.

There is a trouble-shooting LED on the green PCA, red arrow in figure 8, that provides combinations of long and short burst when there is a problem. A listing of the error codes can be found in the service manual, or the inside cover of the unit. We were able to feed paper into the unit at this time, although the test does not call for it. Paper would either deliver into the top bin, or into the third bin from the top. This is probably dependant upon the point of cycle of the reversing gears and when paper was fed. Opening of either of the paper access doors will stop this test.

Standalone Test

The Standalone running test is designed to run paper through it’s path in either mailbox or stacker mode. Mailbox mode delivers paper to each bin one at a time starting from the top and working it’s way down. The DIP switch settings in the 8100 service manual are different from the inside cover settings, but both do the same thing. This is a great test for making sure paper delivers to all the bins.

The stacker version of the standalone running test delivers paper to the bottom bin until it is full, then starts delivering paper to the next bin up. To more quickly test the function of paper delivery to the different bins, you may trick the bin full sensor to get paper to deliver to the next higher bin. You can feed 125 sheets into the unit to fill up the bottom tray, or try to rig the sensor arm in the bin.

The actual photo sensors are located on a long thin brown board near the power supply and controller PCA. See figure 9. You can hold the sensor flag in position to get paper to be sent to the next higher bin. This will only happen after the last three sheets are delivered. Then it will deliver the fourth sheet to the next higher bin. Trying to stuff 125 sheets into the bin from the bin side does not work as the paper ends up resting on the sensors and not lifting the sensors into the bin full position, causing a paper jam. Another good shortcut is that if you need to test the third bin down from the top, for instance, in stacker mode, set the fourth bin full sensor to bin full position by holding, or taping, the sensor into place. Turn on the power supply after setting the bin full sensor and the next sheet will deliver to the third bin.

In other words, we don’t have to fill all the bins from the bottom up. The way stacker mode works, is once the bins are full to the top, it will then look for an open bin starting from the bottom.

Sensor Test

The last mode is the sensor test. In this mode you can test each of the sensors of the mailbox unit. Set up is the same as the others with the exception that you do not need to activate the interlock switch, and it is important to make sure there is no paper in the bins or paper path. Once the DIP switches are set, pull out the blue arm and begin to toggle sensors. This will light the LED on the controller PCA. If the light stays on from the start of the test, one of the sensors is actuated. This can be trouble-shot by checking all the sensors to see if one is stuck in position.

I’m still surprised to hear how many technicians don’t know about these internal diagnostic tests. These are invaluable trouble-shooting tools. To me, not knowing about diagnostics such as these are like going on a service call without a #2 Philips screwdriver. And as I’ve pointed out in this article, and others, the majority of this information is in the service manuals; they’re worth the expense.

For those technicians who do carry around your full set of tools, I hope some of the extra tips in the article help you become a more valuable technician.

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