HP97 powers on and nothing works.


I tried to use a HP97 not used for a long time. I charged the dead battery and the calculator worked in manual mode. I tried to use the card reader. Card will not pass through. Got stuck and card had gummy substance on its side. Wiped it clean and tried it couple of times. Tried to use the clenaing card. The motor tried to work and then the whole calculator went dead. I charged the battery and now when I turn it on it displays all '0's 13 of them with negative sign in front. No other keys work, card motor doesnt feed the card and the printer drive switch doesnt work. Only on/off swith works.Can any one tell me how big is the problem. Can it be fixed. I came across this forum too late trying to get some info. I wish i had known before. I cannot touch any other calculator without RPN. I mostly use 15C.


The gummy substance is from the card reader's drive wheel. These wheels degrade over time and your 97 has the tell-tale signs (gummy subtance on the cards). There are several delicate micro-switches in the card reader. The disintegrating drive wheel may have caused one of them to become stuck in the on-position and this is causing the calculator to hang.

So I would start by replacing your card reader's gummy wheel. While replacing the gummy wheel you will be able to clean all of the switches. I just replaced mine last week utilizing the instructions located elswhere on this site: http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/articles.cgi?read=180
The operation was a complete success thanks to these instructions (thanks Mike!). It is a reasonably straight forward procedure but you need to be VERY careful because a slight slip of the hand could make a mess of things.

By the way, the outer diameter of the silcone tubing is ~6.2 mm.

Good luck and let us know how it goes,

Edited: 3 Aug 2004, 11:17 p.m.


A display of al 00000000 is almost always caused by a bad ACT chip. The HP97 power supply is fairly good and the ACT hardly ever goes bad in this machine (unlike the smaller Woodstock series machines like the HP25).


Thanks Andy and Dave for your input. The Rubber Ring definitely needs replacing. If the ACT chip is bad is it readily available. It may be beyond my scope to repair it myself. I have to get it repaired through one of the services advertised only thing is how much it will cost and is it worth it. Thanks.


If the chip is readily available, e.g. from a spare parts machine, the repair job is definitely worth it. Come on, te 97 is such a great machine! They did not know SMD by then, so the soldering job will be rather easy.



The ACT from an HP21/25/25C/67/97 should work fine. The HP27 ACT is not compatible.


I fixed the problem of gummy wheel but the display of all 8's is still there. Any idea where I may be able to get the ACT chip. Thanks.


The ACT is a custom HP part. You can use one from the HP21/25/25C/29C/67 but not the HP27. It is the 22 pin 0.4 inch wide chip at the bottom of the circuit board. A display of all 000000000 is the standard bad ACT symptom. I'm not so sure about 8888888888.


It was a typo error.It displays all '0's not 8. Do I have to look for an old HP calculator and cannibalize the ACT.


Yes, the HP21 is probably your best bet... they are generally cheaper and less likely to be bad than the HP25. Your other option might be to buy another HP97. They can be had on Ebay for fairly cheap if they have some cosmetic problem. If it has a good main circuit board is is fairly easy to swap out.


I have an old 21 that works perfectly that you can have if you feel up to unsoldering and transplanting the ACT chip...let me know.

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