HP97 The journey begins

[Paul Berger (Canada)]

(01-11-2019 05:51 AM)teenix Wrote:  When it is reassembled, I will try out what you mentioned. It is interesting that it moves that far before figuring out there is no paper. The magnetic carriage return switch must keep the reed switch shorted for a bit of the initial carriage travel. I haven't figured out how the paper out mechanism works, it looks like 2 wires that go to 2 metallic plates that are close to or rub up against the paper.

cheers

Tony

It moves that far to actuate the paper feed which is the only way to get paper in. You may have noted a ridge running along the plastic sleeve over the shaft of the feed roll which also has teeth on the right end that mate with teeth on the right roll to form a ratchet. That ridge rides in a groove in the print head carrier, so as it moves left the sleeve is rotated upwards far enough that the ratchet jumps up 2 teeth and then when the carrier returns, it is rotated downwards which engages the teeth and feeds the paper forward.

While I think of it it seems common for the tire on the feed rolls to get hard and smooth causing irregular feeding of the paper. I have replaced them with a slice of silicon tubing. If you do that, there is a ridge under the tire you will likely need to carve off.

There is also the idler gear which often falls apart I have a spare made of aluminum if you need one.

Paul.