9810 question and offer

[Katie Wasserman]

(02-16-2014 09:09 AM)Tony Duell Wrote:  [quote='Katie Wasserman' pid='5030' dateline='1392492753']



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.

Tony,

Yeah I forgot about the bottom board. On the schematic included in the DVD set they show these "high voltage buffer" IC's U1 and U2 with part number 1820-0668 (aka 7407 non-inverting hex buffer) and U3 and U4 as 1820-0471 (aka 7406 inverting hex buffer). The schematic is dated 1972, after the release of the 9810, so likely they changed the board design in later models.