HP Portable Plus LCD

[aj04062]

Does anyone have experience troubleshooting missing pixel rows on a Portable Plus?

[Martin Hepperle]

(07-05-2016 10:34 PM)aj04062 Wrote:  Does anyone have experience troubleshooting missing pixel rows on a Portable Plus?

Hi,
so far I did not have this problem. I guess you have already opened the machine and reseated all ribbon cables? Make sure you are well grounded - there are many sensitive CMOS parts in the display module.

You might also want to read through the Service Manual to see where else a bad connection could be located in the display module (hoping that it is only a contact problem).

I don't know whether there is a flexprint/rubber pressure pad combo involved, maybe immediately at the display - these are well known for losing contact pressure over the years (a typical problem for the HP 48 calculator family).
Martin

[4ster]

(07-26-2016 02:12 PM)Martin Hepperle Wrote:  

(07-05-2016 10:34 PM)aj04062 Wrote:  Does anyone have experience troubleshooting missing pixel rows on a Portable Plus?

Hi,
so far I did not have this problem. I guess you have already opened the machine and reseated all ribbon cables? Make sure you are well grounded - there are many sensitive CMOS parts in the display module.

You might also want to read through the Service Manual to see where else a bad connection could be located in the display module (hoping that it is only a contact problem).

I don't know whether there is a flexprint/rubber pressure pad combo involved, maybe immediately at the display - these are well known for losing contact pressure over the years (a typical problem for the HP 48 calculator family).
Martin

I'll be following this, my Garmin GPS has had a couple of missing lines appear on the display last year. I have yet to Googleate the problem to see if there is a fix.

On the flexprint/rubber pressure pad: I have an old Fluke 12 meter that uses these as the connections for both the display and for the selector switches for the measurement functions. When the switches didn't work anymore I could take the pad out and use an eraser (or my blue jeans) to freshen up the pad's contact surfaces and the switches would work again. That worked for a long time but doesn't now. I bought a "new" HP 3468A Digital Multimeter in part to replace my "old" and dying Fluke 12. ;-)

[Dave Frederickson]

It's apparent the LCD panel itself has failed. The interface cable doesn't have discrete signals for pixel data.

Do you really want to try to repair the LCD? It's probably easier to find a PPLUS on eBay and salvage the panel. My most pristine PPLUS was had for only $30 a couple of years ago.

Dave

[Paul Berger (Canada)]

(07-05-2016 10:34 PM)aj04062 Wrote:  Does anyone have experience troubleshooting missing pixel rows on a Portable Plus?

If you are missing just a line or column it is likely that either a driver or connection between the driver chip and the glass has failed. It does not look like this display uses elastomer type connectors between the glass and the circuit board, however I don't want to remove the metal frame from the display module to find out. It is likely that this would be difficult to repair.

I do have a spare display for a Portable Plus that is in good condition, send me an email if you are interested.

Paul.