I am having trouble with the display on my TI-86: Rows of pixels come and go daily.
On some days, all rows are fully functional and on others, as many as 12 rows stop working.
Sometimes going into the mode menu and cycling the contrast between the lowest and highest will bring the rows back to functionality, but most of the time it doesn't bring all of them back. When I run the self-test by pressing 2nd-MODE-ALPHA-S on the calculator and get to the part where it turns all pixels black, the rows disappear and look to be functional. As the screen lightens up, the rows are still out.
I would like to know how I can fix this issue. I have opened up the calculator and have tested the continuity of the white flex cable connecting the motherboard to the display driver and all appears well. (I am not sure if differing resistances from data line to data line on this cable can be causing the issue.)
There is a black ribbon cable that is difficult to investigate since the ends of it are sandwiched between the LCD glass and the display driver's board. I have tried manipulating both cables while the calculator is powered to see if the display functions correctly to limited success. Sometimes manipulating the black cable will cause a different row to go out and come back in, but no matter how hard I try, I cannot get the rows that were initially causing problems to work. Sometimes just letting the calculator sit will cause rows to come and go, even the stubborn rows.
I plan on replacing the white flex cable with 30AWG wire to see if anything changes, but I believe it to be impossible for me to replace the black ribbon cable.
TL;DR
I believe my issue is caused by the flex cables (especially the black one), but running the self-test will always cause the dead rows to appear to be working when the test turns all pixels black.
Does anyone know of this behavior on other calculators (rows appearing somewhat functional during the black screen portion of a self test or when menu text is on the same row)?
Any advice on how I should attempt to fix my issue?
On some days, all rows are fully functional and on others, as many as 12 rows stop working.
Sometimes going into the mode menu and cycling the contrast between the lowest and highest will bring the rows back to functionality, but most of the time it doesn't bring all of them back. When I run the self-test by pressing 2nd-MODE-ALPHA-S on the calculator and get to the part where it turns all pixels black, the rows disappear and look to be functional. As the screen lightens up, the rows are still out.
I would like to know how I can fix this issue. I have opened up the calculator and have tested the continuity of the white flex cable connecting the motherboard to the display driver and all appears well. (I am not sure if differing resistances from data line to data line on this cable can be causing the issue.)
There is a black ribbon cable that is difficult to investigate since the ends of it are sandwiched between the LCD glass and the display driver's board. I have tried manipulating both cables while the calculator is powered to see if the display functions correctly to limited success. Sometimes manipulating the black cable will cause a different row to go out and come back in, but no matter how hard I try, I cannot get the rows that were initially causing problems to work. Sometimes just letting the calculator sit will cause rows to come and go, even the stubborn rows.
I plan on replacing the white flex cable with 30AWG wire to see if anything changes, but I believe it to be impossible for me to replace the black ribbon cable.
TL;DR
I believe my issue is caused by the flex cables (especially the black one), but running the self-test will always cause the dead rows to appear to be working when the test turns all pixels black.
Does anyone know of this behavior on other calculators (rows appearing somewhat functional during the black screen portion of a self test or when menu text is on the same row)?
Any advice on how I should attempt to fix my issue?