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+--- Thread: HP-11C display decay (/thread-135951.html)
HP-11C display decay - Jerry Natowitz - 04-15-2008
I have an HP-11C that several months ago started developing a problem with the display.
The lower right corner of the display has turned black.
It is black regardless of whether the calculator is on or off.
I tried new batteries, same thing, black with or without batteries.
The black area is roughly triangular, with side of about 5-6 mm.
The blackness has spread along the bottom of the display, reaching 1-2 mm in some areas.
Is this anything that a slightly klutzy SW Engineer could repair?
Re: HP-11C display decay - Raymond Del Tondo - 04-16-2008
The display is 'bleeding'.
If you're unsure what this means please do a search for the related words 'LCD' and 'bleeding';-)
The only possible repair is to replace the display unit.
HTH
Raymond
Re: HP-11C display decay - db (martinez, ca.) - 04-16-2008
it's boned, but slowly. since it's the right hand side; you probably have a couple of years till this is a big problem. first you have to find a screen of the right vintage. the best bets are from an old 12c or an 11 or 15 that got slammed in the tailgate but only folded the keyboard. then you're going to have to learn the art of fine soldering. you might also check with INTLCALC@aol.com or fixthatcalc.com.
Re: HP-11C display decay - Raymond Del Tondo - 04-17-2008
Hi,
there's at least one variant of the Voyager PCB layout where the display isn't soldered.
In this variant the contact between the LCD and PCB is made
through the awful 'zebra stripe' type rubber connector bands,
and the LCD housing is held in place by a metal clasp.
This PCB variant normally is the one where you have to remove _all_ heat stakes
between the PCB and the upper calc housing first to even get to the LCD...
I did this more than once, and I don't suggest it to the average user;-)
However the PCB variant where the LCD sits on it's own small PCB may be easier to handle,
at least if you swap the whole small PCB, not just the LCD unit,
since the small PCB holding the LCD and ROM is connected to the kbd PCB
using a small and fragile one-time connector pad.
This connection can be made at least twice if you're careful enough.
The limitation is that you have to find the suitable replacement, with the suitable ROM...
HTH
Raymond