HP42S - Display repair

[TomC]

I've got a HP42S in which some of the rows and columns are failing.

I assume there are 'zebra strips' in there that are failing.

Has anyone repaired this type of failure and could share their experience(s)/

Thank you,
TomC

[wojtek]

Just try to take off both zebras and then apply them again very carefully. Of course if it is posssible in 42s without disassembling the keyboard (I don't know this as I have no 42s)

[mfleming]

There have been a few discussions about replacing the LCD on a 42S, with observations about which calculators make suitable donors (like 17Bii) and variations in LCD models over time (try to get a donor produced around the same time as your 42S).

Have a look at the article Pioneer "Observational Internals" (article #5) in the old article archive here:

http://www.hpmuseum.org/cgi-sys/cgiwrap/...ticles.cgi

There is some good information on opening the case and removing the LCD. I found the article and others in the article list useful when replacing a "cooked" LCD display on an HP22S using an LCD taken from an HP14B donor. All you may have to do is replace the zebra stripes, in which case a donor in the same display class (131 by 16 graphic) as the 42S may be all you need.

Usual warning: Take care, work slowly, watch how much force you use on the LCD, and try to be as accurate as possible with alignment. I was delighted to see the new display light up properly on powering the calculator after the repair!