Printer help - HP-IL error loop broken

[Paul Berger (Canada)]

The DC resistance across the pairs at the printer will be quite low as each pair is connected to one winding of a transformer, this would suggest that the wires between the connectors and the board are ok.

Simple cable check use a cable to loop In to out on the 71 and execute "control on" if the is ok you should get a blank display almost immediately, if there is a problem there will be a pause and then it will display "Link open" If all your cables check out good then it would appear to be a fault in the printer, and to cause a link open it would be the HPIL chip or one of the components between it and the connector. If the power light comes on normally that would suggest that the 5V in the printer is good and that is the only voltage the HPIL chip uses Vcc=pin 1 and Gnd= pin 10 on 1LB3 chip.

Paul.