Re: HP-85 Refurb - Print Head Belt



#7

Instructions for replacing the print head belt on the HP-85 suggests a 7/64 ball point hex screwdriver. Fine if you have one. I might need it again in 20 years when the new belt breaks or wears out.

Is there a way to do the job without that tool? Do they sell these at Home Depot? Radio Shack?

My choice is to see if they have one at Sears (across town), find one on the web and wait a week, or seek an alternative. Just wondering about the later.

Looking at it, the specified tool is clearly what HP intended for the job. But, it also looks like removing the motor mount screws (awkward access to the screws, but...) and pivoting the shalt might allow the belt to be removed, but it also looks like a great way to bend the shaft.

I'll ask some of the technicians at work on Monday if they have the tool, but I doubt we use these very often.

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#8

Use an Allen key, these can be found in sets of either imperial or metric sizes and are likely to needed again and again.

Regards,
John


#9

The allen key worked fine, no need for the ball point head version of same. Don't know why the instructions called for one. I figured the author knew something I didn't.

Now, how do you get the belt into the little slot on the print head!

I tried easing it in, but it don't want no easy and I don't want to pry the thing apart becaus I know I'd break it. The belts from the guy on eBay may be thicker than the original, but then again my original was close to evaporating and I've never seen one new except in pictures. I'm thinking of removing the teeth in segment that goes into the slot, but only when I get super desperate.

Any suggestions?

Desperate is next week.

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#10

Take a very sharp (new) rasor blade and shave off a tiny bit of the ends of the teeth on the belt (about 6 teeth that fit in the slot). You only want to take a very tiny bit off to let it slide in with a little friction. It will still hold very well.


#11

Thanks!

I'll give it try this weekend.

It looks like belt should fit, but it won't go in.
I would have removed the entire group of teeth without this advice.

Hopefully, I'll get the major mechanical issues settled soon.

One remaining problem is with a few of the keys (six of them). They work great with the key cap off, but they stick with the key cap on. I don't see any mechanical interference and I have cleaned the keycaps and the keyboard. Do the springs just get weak?

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#12

I repair these all the time and have never used anything but a screwdriver. If you have the right size belt, you don't need to adjust the hex nuts.


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