HP 48SX screen annunciator area smear

[striegel]

My latest acquisition is an HP 48SX from 1990 that arrived today in near-mint condition. Apparently it was very little used in the last 26 years - even the rubber feet seem to have no wear. If not for the roughly engraved initials of a previous owner on the back, I'd call it unblemished. ...except for the very top of the display.

The portion outside of the dot-matrix screen where the annunciators are has obvious smears at each of the fixed positions. It's only apparent when power is applied, so it's not LCD leakage.

I tried to attach close-up images below that show the alpha annunciator area with power on when it's inactive and active, respectively. (Lately I've been unable to make images work in my posts.) With power off, there is nothing to see there.
       

Is this common? Do others have this? I've read complaints about the contrast of the screens of the 48S and 48SX, but I don't think this is related.

[Raymond Del Tondo]

(06-05-2016 01:26 AM)striegel Wrote:  It's only apparent when power is applied, so it's not LCD leakage.

I think it's LCD bleeding. I have seen this on several SX units, mostly on pre-E and some early E units.

[striegel]

(06-05-2016 02:49 AM)Raymond Del Tondo Wrote:  

(06-05-2016 01:26 AM)striegel Wrote:  It's only apparent when power is applied, so it's not LCD leakage.

I think it's LCD bleeding. I have seen this on several SX units, mostly on pre-E and some early E units.

So, if this bleeding is confined to the annunciator area at the top of the screens, have you got a theory of why it happens this way? Factors like heat or vibration?

This particular machine came from Texas, where it gets considerably hotter for longer than around here (northeast Ohio).

Also, where is the dividing line for the early units? Mine is from 1990, week 35.

[Raymond Del Tondo]

(06-10-2016 05:18 PM)striegel Wrote:  

(06-05-2016 02:49 AM)Raymond Del Tondo Wrote:  I think it's LCD bleeding. I have seen this on several SX units, mostly on pre-E and some early E units.

So, if this bleeding is confined to the annunciator area at the top of the screens, have you got a theory of why it happens this way? Factors like heat or vibration?

This particular machine came from Texas, where it gets considerably hotter for longer than around here (northeast Ohio).

Also, where is the dividing line for the early units? Mine is from 1990, week 35.

The dividing line should have been the units with ROM rev. E , but even my E shows the bleeding signs. Don't forget these machines are older than a quarter of a century, and the machines were not made to last that long...

Actually, many units from 1990 (mostly Rev. B to D) were prone to LCD bleeding due to LCD manufacturing problems, so you were lucky to face the ageing effects just now, and not in the early years;-)

[auronthas]

(06-05-2016 01:26 AM)striegel Wrote:  Is this common? Do others have this? I've read complaints about the contrast of the screens of the 48S and 48SX, but I don't think this is related.

Hi, I am newbie and sorry to bring up this post. I have mine 48SX since early 90s during college year, having the similar LCD 'bleed' on some of icons (shift, alpha) on first row. The LCD screen turn fade and dim over time.

My question is if changing polarized/silver coating thin film will improve the LCD screen or I need to get a similar or equivalent LCD screen i.e. 39G/49G ? Appreciate some advise from you. Thanks in advance.

[Raymond Del Tondo]

(06-18-2024 07:07 AM)auronthas Wrote:  My question is if changing polarized/silver coating thin film will improve the LCD screen or I need to get a similar or equivalent LCD screen i.e. 39G/49G ? Appreciate some advise from you. Thanks in advance.

The straightforward solution is to replace the LCD by one of the 39G/40G/49G .
IMHO fiddling with polarizers would be senseless, since much better displays are available (39/40/49),
and bleeding of the old LCD would not disappear.
Hints on how to actually replace the LCD can be found in this forum.