Konica Minolta +350 black unit problem

[jummamaster]

we have a new konica minolta +350 machine. Color units are working well but the black unit only prints on top and bottom of the paper. Laser unit, HV board, Black unit have been replaced/ checked but problem still exits. any help

[brent]

this is a new copier? or (new)to you? I had a black iu fail on my yesterday. a shook a new unit really good and put it in. then the copy quality took a dive. so mabee it is just the defective black unit. basically take a color copy and put it on the glass. then select (black) that is where you can tell if it is the 3 units or a black unit.. also have you went into your tech rep mode and printed off all 4 colors in the test color charts? and lastly are you getting any p codes? we need more info.

brent

[time2fly]

Try adding toner from the toner cartage, put the toner on a piece of paper and dump it into the IU then do a stabilize. Good Luck

[jummamaster]

this is new machine, only few thousand copies have been made.
Black developement unit and drum have been checked on another machine. They are not defective.
In tech rep mode CMY test chart are printed good but black disappears in the middle of the page.
There is no code on the display.

[cobiray]

Have you tried swapping the ribbon cables for the LED unit?