HP Forum Archive 18

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HP-41CV zebra strips Message #1 Posted by Tim on 6 July 2008, 10:35 p.m. I am having problems with the conductivity of my zebra strips that connect the two circuit boards in my HP-41cv. When I try to use the cardreader the voltage drop across the zebra stip rises to 2v SO the low battery indicator goes on and the cardreader does not move. Does anyone know how to repair or obtain zebra strips?

Re: HP-41CV zebra strips Message #2 Posted by Raymond Del Tondo on 7 July 2008, 12:28 a.m., in response to message #1 by Tim If you look at the 'zebra stripe' with a magnifyig glass, you'll see it's made of a series of very thin and separate contact rings, or alternatively contact blades if you have the pink rubber type stripes... The only cure seems to be replacing non-working stripes with working ones from another HP-41. Athough some company other than HP must have made these stripes, and someone may still be making these or similar, I don't know who. BTW:I saw at least one HP-41 where the stripes had been replaced by soldered wires, but that's not something for the rough types;-)

Re: HP-41CV zebra strips Message #3 Posted by Diego Diaz on 7 July 2008, 3:55 p.m., in response to message #2 by Raymond Del Tondo Hi all, Zebra strips have been a recurrent source of failures for the 41 series. However, the power for the Card Reader (nor for anything connected to the I/O block for that matter) has nothing to do with this part. Only the CPU board gets its supply thru that Zebra connector. Since you have detected a significant voltage drop when operating the Card Reader, chances are that you have a bad contact (highly resistive) between the I/O block flex connector and the Keyboard PCB, which is quite frequently due to some corrosion from leaking batteries. It can also be caused by cracked post or loosen screws. Hope this can help. Diego.

Re: HP-41CV zebra strips Message #4 Posted by Tim on 7 July 2008, 9:56 p.m., in response to message #3 by Diego Diaz The voltage drop is occuring across the strip that feed power also to the logic board. All the Power from the battery that I can trace out flow to the zebra strip then it fans out. I do not have the schematic.

Re: HP-41CV zebra strips Message #5 Posted by Muhammad Ahmad on 26 July 2008, 1:03 p.m., in response to message #1 by Tim You can try to clean them. Even rust can be removed with WD-40. Take a Q-tip and apply some WD-40 on it and then clean the metal contacts on both ends, i.e. the PCB and the Flex cable. Once the thorough cleaning shows that the golden pads are clean, you can then use alcohol to remove the oily residue of WD-40 or even Windex. But this needs to be done with Q-tips. Avoid any of the cleaning fluid seepage into other areas. Do it very gently and precisely. Once the contacts have been cleaned, you can take an eraser and rub it on the contacts to remove any other stuff. This should remove any debris created by oxidation. Use a magnifying glass if you have to. The work needs to be done very precisely, almost as if you are working on fine pitched SMD devices. Hope this helps, and let me know if you have success. Good Luck!!! As a last resort, try changing your batteries with a set of fresh new ones. Muhammad

Re: HP-41CV zebra strips Message #6 Posted by Tim on 26 July 2008, 4:42 p.m., in response to message #5 by Muhammad Ahmad Worked. Thanks alot.

Re: HP-41CV zebra strips Message #7 Posted by Muhammad Ahmad on 27 July 2008, 12:46 a.m., in response to message #6 by Tim Tim, Just curios, did the cleaning work or new batteries? Muhammad

Re: HP-41CV zebra strips Message #8 Posted by Tim on 29 July 2008, 6:05 p.m., in response to message #7 by Muhammad Ahmad The cleaning. I used alcohol and did not touch the strips like you said. I works perfect now. Thanks.

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