Posts: 1,162
Threads: 26
Joined: Aug 2005
No, the printhead has 7 (IIRC) elements in a vertical line and puts down entire characters as it moves across the paper.
If you're missing the top row, then I would suspect :
The flexiprint cable that links the head itself to the lower (PSU/printer) PCB. Alas repairing that is next-to-impossible.
The head itself
A driver transistor (I think there are a pair of quad transistor array 'chips') on the PCB, like in a Topcat.
The PIK (Printer Interface and Keyboard) chip on the logic PCB.
You can get schematics on the HPCC CD-ROM.
I measure the resistance between the common connection on the printhead flexiprint and each of the others in turn. If one is much higher than the others (or is open-circuit), then you have a head/flexiprint problem.