Zero Black (not clogged)

[printcore]

Hey guys, Roland sp540i, so after zero ink on prints i replaced transistors and got successful test print until i noticed air in ink line and leak from manifold, replaced these fitted dampers, pulled ink through capping tops successful.
After this there suddenly is ZERO BLACK when doing a test print. Cables replaced still same, whats the ods that a single transistor failing "again" is possible and moreso will a transistor fail affect only one line on a single print head.
Not concerned about the missing nozzles they will return, but cant think whey only the black that was 100% before fiddling is now a Zero.
Yes guys i have disconnected and released all power from the caps.
Any ideas , guess ill remove main board to test again tho.

 

[MikePro]

before ripping out your board and messing with it some more....try a line of diagnosis by swapping data lines at the printhead. if you swap the K data with any of the other MCY channels, and the error follows to the other color, then you find ways to diagnose up the chain of data transmission to eventually reach the board. if the error stays in the black channel, then its the ink lines or below the data/electronics.

 

[netsol]

good idea.

POWER OFF MACHINE & WAIT 15 MINUTES BEFORE CHANGING CABLES. check for bent or shorted foils.

we don't want to make a new problem

 

[Terry01]

Swap your black and cyan cables over at the printhead and test print again..

 

[printcore]

good idea.

POWER OFF MACHINE & WAIT 15 MINUTES BEFORE CHANGING CABLES. check for bent or shorted foils.

we don't want to make a new problem

before ripping out your board and messing with it some more....try a line of diagnosis by swapping data lines at the printhead. if you swap the K data with any of the other MCY channels, and the error follows to the other color, then you find ways to diagnose up the chain of data transmission to eventually reach the board. if the error stays in the black channel, then its the ink lines or below the data/electronics.

Thanks just swopped cables Cyan still prints on swop but, still no black, ink is clear all the way through on cleaning, just zero on printing

 

[printcore]

before ripping out your board and messing with it some more....try a line of diagnosis by swapping data lines at the printhead. if you swap the K data with any of the other MCY channels, and the error follows to the other color, then you find ways to diagnose up the chain of data transmission to eventually reach the board. if the error stays in the black channel, then its the ink lines or below the data/electronics.

Can i swop those 2x cables i tried the head cable swop but problem stays on black

 

[Terry01]

Did you follow instructions? Did the cyan shift over to where the black should be printed? If so, the head is fried.

 

[printcore]

Did you follow instructions? Did the cyan shift over to where the black should be printed? If so, the head is fried.

I swopped the cyan cable with the black cable on the head side, cyan still fires but not the black

 

[Terry01]

The head is fried then.. You require a new one.

 

[printcore]

So i tested the Transistors, and 3 of them gives me 12.6 and 1 gives me 11.1 on the OHM 20K setting i dont have a propper testor with diode setting. I will only get to work on it end of Mei and will revert here once ive replaced Transistors. With sum luck else its new head ig.

 

[damonCA21]

The transistors should all test the same within a small amount, it does sound like one of yours is faulty.

 

[netsol]

in order to test the semiconductor junction, you need to reverse the leads and see ALMOST OPEN (no reading) in one direction & your 12.6 or WHATEVER in the other direction
you may have to check the DRIVERS (the smaller transistors, 1 STAGE BACK from the outputs. they do not NORMALLY go bad.
did you check the ribbon cables?
did you CAREFULLY check for the 41 volts dc on the collector of the transistor whose number begins 2SC (the npn component of the complimentary pair)