Printer help - HP-IL error loop broken

[coitboy2000]

Hi

I have an HP 82162a that will not respond over hp-il. My hp-71b reports that the loop is broken. The printer paper feed button etc does what it should. I have tried multiple leads, checked the resistance across the hp-il plug after opening the printer, replaced one of the capacitors that looked suspect, all to no avail. I still get the loop error. The resistances were 0.7 to 1.0 Ohm.

I did manage to find an electronic schematic of the internals by Tony Duell but I am out of my area of expertise. I noted 2 resistors measured 7.5k OHm instead of 15 but I may be looking at the wrong ones. Any ideas or suggestions on what to try much appreciated. Such a shame as the printer is extremely tidy inside and out.

Regards

Richard

[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.

[coitboy2000]

Thanks Paul. The cables check our and power seems to be getting tbrough. I will try to trace the circuit between the hpil chip and connectors as you suggest. I have been reluctant to pull the whole board out. Is there anything mounted to the underside of the circuit board?

Richard

[Paul Berger (Canada)]

(07-22-2018 08:22 PM)coitboy2000 Wrote:  Thanks Paul. The cables check our and power seems to be getting tbrough. I will try to trace the circuit between the hpil chip and connectors as you suggest. I have been reluctant to pull the whole board out. Is there anything mounted to the underside of the circuit board?

Richard

I don't recall any component on the bottom except the LED Indicators.