HP LJ 8000 2,000-Sheet Tray Stand-Alone Tests

The second-generation Tray 4 (Model No. C4781A) has a stand-alone tests feature. Unlike the first-generation Tray 4 (Model No. C3763A for the LJ 5Si), the new Tray 4 can be manually powered on and put into any one of three tests. The rear cover must be removed for access to the power supply switch lever, and the test selection DIP switch on the logic PCA.

The three tests are motors test, sensors test and running test.

Motors Test

>Switches 1, 2 and 4 on.
>Drawer open. The test will not run if the drawer is closed.
>The VTU can be open or closed.
>Power switched on. There's about a two second delay before the test starts.
>All three motors run constantly. The deck elevation motor runs to no effect because the drawer is open. (Rotation is counterclockwise as viewed from the back.)
>The VTU's electromagnetic clutch is kept energized, so the lower roller should be turning constantly.
>The pickup solenoid is kept energized, so there's a constant clicking noise from the cycling pickup mechanism.

Sensors Test

>Switches 3 and 4 on.
>Drawer and VTU open.
>Power switched on.
>Actuating any sensor toggle or switch lever causes the LED on the logic PCA to illuminate. This is an excellent test for finding unreliable paper size sensing switches. Each switch closure should be sensed with only enough pressure applied to its lever to cause it to click over. Any switch that requires extra pressure to cause the LED to go on is likely to give intermittent trouble.

Following are all the items that can be tested:

>Each of two paper quantity switches.
>Each of four paper size switches. (Note that these switches are also the means by which a 'drawer closed' condition is sensed. There is no physical paper size configuration that doesn't result in at least one switch being actuated.)
>Top-of-stack/deck-floor sensor.
>Paper out sensor.
>VTU open/closed sensor.
>VTU entry sensor.
>VTU exit sensor.

Running Test

>Switches 1 and 4 on.
>Paper in drawer and drawer closed.
>VTU closed.
>Power switched on. There's about a two second delay before the test starts.
>The VTU motor runs briefly, then stops.
>The deck is elevated.
>The tray commences picking up and feeding sheets up and out the VTU. 'Easiest way to stop the test is to open the VTU; then you'll have to clear a stalled sheet or two out of the works. The test will restart if you close the VTU.

Error Conditions

Error conditions are reported by way of long and short LED flash sequences. There's a table of them inside the rear cover of the unit.

Closing Up

Don't forget to set all four DIP switches to off. Note that the power switch lever is constructed in such a way that installing the rear cover forces the lever to its normal position.