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HP Forum Archive 19

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Restoration Help
Message #1 Posted by Egan Ford on 12 Mar 2009, 1:07 p.m.

I just read about this today. IIRC, there have been inquiries about how to clean old calcs in the past. Perhaps this will help a few of you: http://retr0bright.wikispaces.com/

      
Re: Restoration Help
Message #2 Posted by Steve (Australia) on 25 Mar 2009, 6:11 a.m.,
in response to message #1 by Egan Ford

A friend of mine used this on a junky HP21 of mine while he was doing his Vic-20 and I am impressed with the results.

My HP21 was nowhere as discoloured as his Vic-20, but the difference is significant.

I have photos if anyone is interested.

            
Re: Restoration Help
Message #3 Posted by Steve (Australia) on 25 Mar 2009, 11:20 p.m.,
in response to message #2 by Steve (Australia)

Here are the images I have at present.

Tim's Vic-20 prior to Retr0brite. This had been stored by a previous owner inverted, on a desk in the sun with stuff piled on it. It looks dirty, but this is actually yellowing of the plastic.

I delivered the HP21 to Tim a couple of hours after he had started his Vic-20 case "cooking". His case is partially done here.

He tool a close-up of the HP21 to show the foam on it. We have a bloody great hole in our ozone layer here, so this probably works better/faster than for northern hemisphere people.

Tim only gave them 3 or 4 hours rather than the all day that is recommended. He used a 6% H2O2.

Here are 2 HP21s. They both looked pretty much the same colour previously. The one on the left is now almost completely un-yellow.

I might try a similar trick on the keys of this HP21. They're not that yellowed, but it would be valuable to know if the keys will be affected. This HP21 has a number of serious cosmetic problems already, so it won't be a huge loss for me if it goes pear shaped.

                  
Re: Restoration Help
Message #4 Posted by Charles Oxford on 25 Mar 2009, 11:38 p.m.,
in response to message #3 by Steve (Australia)

What effect did it have on the feet?

                        
Re: Restoration Help
Message #5 Posted by Steve (Australia) on 26 Mar 2009, 10:44 a.m.,
in response to message #4 by Charles Oxford

It wasn't put on the feet. The stuff is a gel or a foam and can be applied pretty much where you want to put it.

If this calculator were a good one I would have taken the other feet off, or masked them with something. (you may be able to see a masked label on the Vic-20)

Maybe I'll subject the feet (and other parts -- e.g. metal parts) to this stuff to see what happens.


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