HP Forum Archive 14

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HP-48GX strange corrosion problem Message #1 Posted by JeffD on 14 Nov 2004, 7:22 p.m. I have a HP-48GX that was in mint condition but, there seems to be some corrsion growing on the edges of the screen and the edges of the keyboard around the keys. The battery compartment is perfectly clean. Any ideas what this might be? Thanks, JeffD

Re: HP-48GX strange corrosion problem Message #2 Posted by Raymond Del Tondo on 14 Nov 2004, 7:36 p.m., in response to message #1 by JeffD You may have stored the unit in a very hot and/or humid area, or at least somewhere outside the specs given in the manual... Raymond

Re: HP-48GX strange corrosion problem Message #3 Posted by Vieira, Luiz C. (Brazil) on 14 Nov 2004, 8:03 p.m., in response to message #1 by JeffD Hi; I've seen corrosion like this, in fact a few of the units I own have this problem: an HP48SX, a non-working HP42S, an HP15C and an HP11C. All of these have aluminum bezels, and I guess the contamination (oxidation, in my case) is due to one of both causes I can identify: bad environment (as Raymond says) or previous contamination at the production line/chemical aluminun treating. As I have other calculators of the same model without any trouble, and they also have aluminum bezels, I guess this contamination occurs in isolated cases, only. My 1¢. Luiz (Brazil)

Re: HP-48GX strange corrosion problem Message #4 Posted by JeffD on 14 Nov 2004, 10:05 p.m., in response to message #3 by Vieira, Luiz C. (Brazil) Thanks for the responses. I was keeping this unit as my mint condition unit but unfortunately it has this problem. Is there any way to stop the issue from happening any further? Thanks, Jeff

Re: HP-48GX strange corrosion problem Message #5 Posted by karl on 15 Nov 2004, 8:19 a.m., in response to message #4 by JeffD ultrasonic wave cleaner may help

Re: HP-48GX strange corrosion problem Message #6 Posted by bill platt on 15 Nov 2004, 11:03 a.m., in response to message #4 by JeffD If you have salts or other water-woluble materials acting as electolyes, floating around inside, then you might try removing the batteries, and immersing in pure distilled water, rinsing with this distilled water thoroughly, and then drying completely over a period of days. This wil lremove the electrolyte--thereby stopping the source of corrosion. regards, Bill

Re: HP-48GX strange corrosion problem Message #7 Posted by JeffD on 15 Nov 2004, 7:06 p.m., in response to message #6 by bill platt Would the entire calc get immersed? Thanks, Jeff

Re: HP-48GX strange corrosion problem Message #8 Posted by bill platt on 15 Nov 2004, 8:16 p.m., in response to message #7 by JeffD Yes indeed! Just be sure the batteries are out. I know it seems strange, but it has been done many timess---and by some really good experts---seemed strange to me too at first! Do a search of this forum & archives and you will find a number of discussions---search "distilled" "water" "wash" "clean" "corrosion" etc Best regards, and do tell how it comes out! Bill

One question: (was: HP-48GX strange corrosion problem) Message #9 Posted by Vieira, Luiz C. (Brazil) on 15 Nov 2004, 8:29 p.m., in response to message #8 by bill platt Hi, Bill; I read Jeff's first post again and it seems to me that the corrosion/contamination happens only in the external bezel. I am completely sure about the fact that using distilled water to completely emerse the calculator is one (if not THE one) of the best options/procedures, but I wonder if it is necesary in this case. Indeed, having the calculator cleaned this way is also a great benefit for the fuure. Just to know: should it be necessary if the corrosion proves being external only? Thanks and best regards. Luiz (Brazil)

Re: One question: (was: HP-48GX strange corrosion problem) Message #10 Posted by bill platt on 16 Nov 2004, 12:29 p.m., in response to message #9 by Vieira, Luiz C. (Brazil) Hi Luiz, I think that even if the corrosion is "external" the electrolyte must needs be below the surface for corrosion to occur, and therefore in the electronics as well, if it is causing corrosion. For, if it were only on the surface, then the paint would be adequate protection from salts etc. So the question then becomes, will the transient solution cause any harm? My sense is not (provided the batteries are out), as if there is a hydrophyllic corrosive salt in there, it will have been "wet" already, merely from vapor. Off topic, can you email me? (south american musical instruments) my first name at plattdesign dot net Best regards, Bill

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