|Re: how do i give a 25c a bath?|
Message #6 Posted by Vieira, Luiz C. (Brazil) on 28 Feb 2003, 1:03 a.m.,
in response to message #5 by db(martinez,california)
Let me tell you what happened to me a few weeks ago.
I was sent four Woodstocks (not mine) so I would try to repair them. Two of them -HP22 and HP27- showed the same behaviour you mention: random display. The HP22 came back to life after a detailed cleanning procedure. In the HP27 I had to remove the logical set - two IC's - and clean under them. A lot of "cyan" crystals (copper oxide). I used tepid (+) vinegar and I could remove all visible oxide material. Voilá! Both are back to life. The other two are waiting for me for this next week.
There is a possibility of contamination in the display, too. I saw this sort of misfortune in two Spices, because batteries are right under the LED's display. You should inspect to see if the display is O.K. Better yet, you should try the display in another Woodstock, if you have one for testing.
I think there is still some residual between the IC's and the logical board. I must warn you that removing these IC's was not easy: these boards do not have metal-coated holes; instead they have small, thin metal rivets, and the IC's terminals will insist on keeping in contact with them. It's somewhat hard to remove, and in my particular case, there was oxide residual coating inner solder surface. I had to use sharp-edged clips so I could remove the IC's without dammaging the metal rivets. If you are willing to do this, just be carefull and pacient, will yah?
Having a Woodstock back to life worth the job, believe me. And I consider I have been fairly "gifted" (I was gifted a calculator without the need of a commitment to the repairing; I felt myself gifted with the gesture, too), mostly now that my friend's calculators are ready to fly back home.
I hope you have success. Let me know if you need something, O.K?
Best regards and good luck.
Luiz C. Vieira - Brazil