HP-97 saga


Third time's a charm at posting this?

Time to ask the HP Forum about my HP-97.

I picked it up some time ago, and have slowly restored it to life, learning things along the way (such as good batteries being an integral part of the AC power circuit). I'm working on the card reader now, and I've done the O-ring thing (fuel tubing didn't seem to work at first, but I have three feet of it, which ought to be enough for, oh, 1440 years) and now it pulls card through, but it always says Error after doing so. Did I miss some sort of pressure pad to make the card contact the head? I didn't see any obvious way to adjust the head height, either. I don't have any pre-recorded cards, so all my tests are W/DATA, which should be doable right after power-up, no? I'm not sure what the next step is, and taking that card reader apart is getting less fun every time...


Did you take the little gold switch contacts out? Does the card seem to not want to come out when you remove it?


The gold switch contacts were attached to the smaller of the two halves of the card reader assembly. I never removed them. The card goes all the way through, fairly smoothly, now. But it doesn't seem to matter if the card is right-side-up or upside down...


Taking note of Daves mail below, you should also check carefully the head connections to the PCB and the ribbon cable which at this stage will probably be peeling and separating. "Error" can mean many things but one of them is 'card underrun' if the card cannot be removed easily from the drive (however smoothly it runs) then some adjustment will be required.


The speed through the reader is important. The OD of the tubing or rollers affects this speed. I recommend and have had many successes with 1/4" OD Latex surgical tubing. Its surface texture provides better grip than smooth vinyl & does not require texturing.



In my experience, the most likely cause for an 'Error' after an attempt to WRITE a card is a problem with the gold spring contacts. Even if you never removed them, they may be slightly corroded or bent. One of them senses whether the write-protect corner of the card has been clipped; if it provides incorrect information, the machine will believe that the card is write-protected and will refuse to write to it.

I test this with a digital multimeter set to beep on a short circuit, attaching test clips to the appropriate spots on the card reader's circuit board. As you push a card through by hand, you can hear the beep come on as the spring contacts are reached.

Also check the ribbon cable connecting the card reader to the main circuit board.

I don't use W/DATA to write cards for testing by the way; just slide the programming switch to the program position and insert the card. This is how one records programs.


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