9810 question and offer

[Tony Duell]

(02-15-2014 07:32 PM)Katie Wasserman Wrote:  There's just one PCB for printer control/print head driver. It's the one attached to the printer. IIRC you need to remove the printer and it's PCB as one unit. You might was well swap that whole assembly to verify that the problem is with electronics on the printer PCB. The head driver uses a bunch of 5 bit shift registers feeding high voltage buffer/drivers. On the schematic in the HP DVD set it shows these buffer/drivers as IC packages, but on Tony's schematic he shows them as discrete transistors. Possibly they made these PCB's two different ways.

There are 2 PCBs on the printer. Most of the electronics is on the one on the side of the printer (I call it the Interface PCB), there's also one on the bottom containing the prinhead matrix diodes, the 'block' driver transistors and the motor controller. But I agree the most likely problem is on the interface PCB.

I have worked on half a dozen of these printers and all have used discrete transistors. It's possible HP used transistor arrays on some of them, if anyone comes across this version I would love to find out more.