HP Forum Archive 21

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HP-97 Display flickering Message #1 Posted by davorin on 28 Aug 2013, 4:59 a.m. Good morning from Switzerland ;-) Just received a HP-97 this morning and after some resoldering it seems to work. One question though: Is the noticeable display flickering normal? Especially the flickering is heavier in the left hand digits. Or something to do we have here 50Hz instead of 60Hz?

Re: HP-97 Display flickering Message #2 Posted by Marcus von Cube, Germany on 28 Aug 2013, 5:14 a.m., in response to message #1 by davorin Do you have a good battery? The battery is required to regulate the supply voltage.

Re: HP-97 Display flickering Message #3 Posted by davorin on 28 Aug 2013, 5:47 a.m., in response to message #2 by Marcus von Cube, Germany Pretty dead battery pack ;-) But thanks for pointing me in the right direction... Added a small 100uF capacitor across the 5V power supply, close to the AC input where it says "+" and "-" on the PCB...now the flickering has gone and also the printer motor moves...though one gear is worn out...

Re: HP-97 Display flickering Message #4 Posted by davorin on 28 Aug 2013, 7:47 a.m., in response to message #3 by davorin Well....voltage is a little too high now with the capacitor.... Gonna use a standard 5V USB power adapter now to be on the safe side ;-)

Re: HP-97 Display flickering Message #5 Posted by Marcus von Cube, Germany on 28 Aug 2013, 11:01 a.m., in response to message #4 by davorin Replacement battery packs are available online on a well known auction site.

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