This manual is a `follow on' to my manual on repairing the HP9800 series 
of desktop calcualtors. It covers the HP9866A printer that was often used 
with the HP9830 mnachine and which, wjhile being a separaet product, is 
almost a part of that system

After an overview of the printer operation, this manual continuses with 
descriptions of the major sections of the printer electronics, including 
a state-by-state analysis of the control system finite-state machine. Two 
final chapters cover dismantlign the printer and locating faults.

I shall assume that the reader has already read the HP9800 manual and
thus, since much of the general repair tips, necessary tools and test gear
and safety information are the same for the HP9866 as for the HP9800
machines, this information will not be repeated here. 

As in the case of the HP9800 calculators, the official HP service manual 
is mostly a `boardswapper guide', although it does contain schematics of 
the {\bf Logic PSU} and {\bf Motor Driver} PCBs.  A full schematic is 
however available and is almost essential for repairing this printer. The 
source listing of the control state machine is also available, but as 
this is included in a later chapter, it is not necessary ot obtain this 
lisitng. 

