HP-97 Repair

[bmurray]

My HP-97 fell off the table--I sorta helped it do this. There was no obvious visual external damage to the case. When I turned it back on, all of the "A" segments of the display were out, i.e., Zero looked like a U, etc. Somehow in a few days, all of the "A" segments returned to life. I googled and found Vintage Calculator Repair which --miracle of miracles-- is only a couple of miles from me! Unfortunately, their phone was always busy. And I found out why: the owner died in September 2020.

I've had it since 1977 and it has been around the world with me while I was in the USAF. It's family. There was a firm in the mid-west that repaired my HP-67 but they retired or went out of business.

I've not opened it to see if it a simple cable re-insertion. The card reader still works and I can do keyboard calculations. That leaves the printer. It is trying to print: the print head is roughly centered and it stays there; you can hear the motor humming. Pressing Print X or the paper feed button causes the display to blackout.

So is there any reputable firm that can fix my treasured HP-97?

Bill

[teenix]

Opening the 97 is easy if you want to check it out for broken or dislodged items. Just a few screws from underneath.

Try not to touch the components on the circuit boards, only handle boards by their edges. Static charge from your body may damage things.

For the [A] segment, if you are lucky perhaps it is one of the pins connecting the CPU board to the key board. Unfortunately, these pins are brittle and may have broken during the impact. If one was bent causing a bad connection they also don't take kindly to bending straight again.

The battery will have to be held in place if power is required for testing, but you might be able to confirm this by moving the CPU board a bit while watching the display. Looking at the connector pins on the lower left of the board, the [A] segment pin is the 9th pin from the left.

If you need to separate the CPU board from the pins to check them, place a flat bladed screw driver just under the circuit board edge adjacent each of the two connectors and gently lever it up by twisting the screwdriver a bit at a time alternating between both connectors. The front edge of the case will serve as the lever point.

The ribbon cable connecting the display only has small wires going in to the connectors, maybe one of those broke. If so it is a bit fiddly to check this out. The HP-97 service manual, available from the web, explains how to do it. I wouldn't advise removing the ribbon cable from the connectors in case you damage the cable. If there is a break you should be able to see it. If so, fixing this will be fiddly. Worse case, the LED display assembly may have been damaged.

It sounds like the printer idler cog may have broken. This is made out of a resin substance and because of its age has probably become brittle. This would explain the motor running without carriage movement. The 97 is trying to home it but can't and as you found out the 97 CPU stalls if you try and print in this condition. (Blank display) At least you know the CPU board seems to work ok

I hope this helps.

cheers

Tony

(06-18-2021 06:19 PM)bmurray Wrote:  My HP-97 fell off the table--I sorta helped it do this. There was no obvious visual external damage to the case. When I turned it back on, all of the "A" segments of the display were out, i.e., Zero looked like a U, etc. Somehow in a few days, all of the "A" segments returned to life. I googled and found Vintage Calculator Repair which --miracle of miracles-- is only a couple of miles from me! Unfortunately, their phone was always busy. And I found out why: the owner died in September 2020.

I've had it since 1977 and it has been around the world with me while I was in the USAF. It's family. There was a firm in the mid-west that repaired my HP-67 but they retired or went out of business.

I've not opened it to see if it a simple cable re-insertion. The card reader still works and I can do keyboard calculations. That leaves the printer. It is trying to print: the print head is roughly centered and it stays there; you can hear the motor humming. Pressing Print X or the paper feed button causes the display to blackout.

So is there any reputable firm that can fix my treasured HP-97?

Bill

[AndiGer]

If it is the idler gear causing the printer to stall you can find replacement these days.
See here: https://www.hpmuseum.org/forum/thread-16866.html
I also sold some but shipping overseas even small parts turned very expensive.