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Hp 50g vertical display problem
03-22-2016, 02:32 PM
Post: #1
Hp 50g vertical display problem
My 50g has developed between 1 and 3 vertical lines in the display. When present the lines run the entire length of the display and appear at the same location (so far).

Light pressure on the display or twist on the calculator (in the right place) will make the lines go away. The shade of the line(s) is white. And remains white whether that part of the display is blank or should be showing something. It seems the problem is caused by a bad connection to the display.

I replaced the batteries even though the low battery indication was not on. No change in symptoms.

Any suggestions?

Thanks Randy
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03-23-2016, 05:50 AM
Post: #2
RE: Hp 50g vertical display problem
Hello,

You have 2 bad contacts between the PCB and the display.

The contact is done using a heat glued/sealed plastic flexible connector.

Most likely, this has been damaged (or the connection has weakened).

It IS possible, if you are super/very careful to fix such things, but it means opening the calculator, possibly also prying the LCD off and then re-heat glueing the connector strip, which is not an easy feat.

Usually, to do so, you place on the strip some non glue non melt plastic isolator (like anti static tape), and use the soldering iron at low temp to tranfert some heat on the connector and glue it...

I have done it once or twice, but it is hard.

Cyrille

Although I work for the HP calculator group, the views and opinions I post here are my own. I do not speak for HP.
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03-23-2016, 01:46 PM
Post: #3
RE: Hp 50g vertical display problem
Thank you Cyrille. I suspected a loosening and/or weakening connection.

Several years ago I had help and repaired a 39g display connection.

The 50g display repair is more than my capabilities.

I do have a prime but still use the 50g a lot. Guess I need to speed up the transition.

Thanks again. Randy
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03-23-2016, 06:52 PM
Post: #4
RE: Hp 50g vertical display problem
50g to Prime is not a transition it is a downgrade.
There is nothing that compares with the 50g.
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03-24-2016, 11:11 AM
Post: #5
RE: Hp 50g vertical display problem
Anecdote:
That problem used to plague the 48SX at the beginning of the 90s. I got one at the time with 1 missing line, and later it developed into 3 missing lines Sad. The elastomer between the display and the PCB was/is defective, it is a sandwich of rubber and some conductive but flexible compound.

I used to apply some failure locating spray to the edge of the display, and because both compounds have different coefficients of thermal expansion you can see if the problem is there, the lines become visible.
***

Looking at the photos http://s1189.photobucket.com/user/_rs1n_...sort=3&o=8

It looks like they were for the conductive foil ( Sad ), well apply so pressure between the foil and the PCB and see if the lines reappear, then, some glue may help.
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03-24-2016, 07:52 PM
Post: #6
RE: Hp 50g vertical display problem
(03-23-2016 06:52 PM)Tugdual Wrote:  50g to Prime is not a transition it is a downgrade.
There is nothing that compares with the 50g.

I experienced a lot of problems updating my prime operating system. So much so tha I left a note on the hp website. To my surprise, I received a call from a real person. I took the opportunity to add my prime product update requests: Rpl enhancements, DDAYS functions, and key label color improvements. When I finally got the prime updated dday functions were included.

My 49g+ was a good machine until the keys started failing. Eventually the 50g came along and provided a good platform.

I hope hp listens to users and modifies the prime accordingly.
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03-24-2016, 08:51 PM
Post: #7
RE: Hp 50g vertical display problem
(03-24-2016 11:11 AM)Alejandro Paz(Germany) Wrote:  Anecdote:
That problem used to plague the 48SX at the beginning of the 90s. I got one at the time with 1 missing line, and later it developed into 3 missing lines Sad. The elastomer between the display and the PCB was/is defective, it is a sandwich of rubber and some conductive but flexible compound.

I used to apply some failure locating spray to the edge of the display, and because both compounds have different coefficients of thermal expansion you can see if the problem is there, the lines become visible.
***

Looking at the photos http://s1189.photobucket.com/user/_rs1n_...sort=3&o=8

It looks like they were for the conductive foil ( Sad ), well apply so pressure between the foil and the PCB and see if the lines reappear, then, some glue may help.

Thanks for the info. With help I disassembled a hp39g and reseated the display connector. The photos look more complex than the 39g. The failure locator spray is a product I have not used. However, I will wait before I attempt to open the hp50g.
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05-15-2020, 12:15 PM
Post: #8
RE: Hp 50g vertical display problem
(03-23-2016 05:50 AM)cyrille de brébisson Wrote:  Hello,

You have 2 bad contacts between the PCB and the display.

The contact is done using a heat glued/sealed plastic flexible connector.

Most likely, this has been damaged (or the connection has weakened).

It IS possible, if you are super/very careful to fix such things, but it means opening the calculator, possibly also prying the LCD off and then re-heat glueing the connector strip, which is not an easy feat.

Usually, to do so, you place on the strip some non glue non melt plastic isolator (like anti static tape), and use the soldering iron at low temp to tranfert some heat on the connector and glue it...

I have done it once or twice, but it is hard.

Cyrille


I know the post is old, but I have exactly the same problem (see pictures).

Can someone please mark on the picture where I can find the defective spot?

I have a hot air dryer and soldering iron available.

I am thankful for every tip, because I would like to repair the calculator.


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05-15-2020, 12:16 PM
Post: #9
RE: Hp 50g vertical display problem
and one more picture.


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05-25-2020, 08:02 PM
Post: #10
RE: Hp 50g vertical display problem
Hello Forum,

I've made several attempts to fix the calculator.

Here's what I've tried:
  • Heating the display and display connector with a hot air dryer. Then press the connectors onto the PCB.
  • Use of contact oil for the Display-Connectors
  • Pressing the connectors at different places on the PCB

Unfortunately everything has been without success so far. The vertical stripes on the display are unfortunately still there.

Can you please give me another tip?
Where was the break of the connector in your case?

I do not want to dispose the calculator.

Best regards
CK


Ich nehme gerne auch Tipps in deutscher Sprache entgegen Smile Ich weiß die Fangemeinde ist groß
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05-26-2020, 03:18 AM
Post: #11
RE: Hp 50g vertical display problem
I have the same issue. I have about 10 lines on the left portion of the screen which are blank. I've disassembled the calculator and haven't been able to get the contacts which correspond to those columns to reconnect. It's disappointing that my 30 year old 48SX works perfectly but this 7 year old HP50g is now essentially useless. Considering a Prime but I noticed they aren't even on the HP website. I assume the latest model is the V2. Is HP working on something new? I hope we can get our LCD issues resolved.
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05-26-2020, 08:23 AM (This post was last modified: 05-26-2020 08:32 AM by CK1-CK.)
Post: #12
RE: Hp 50g vertical display problem
Is the red or green connector responsible for the vertical stripes? (see pictures)

Probably the red one.



Does anyone know the temperature the plastic strip connector can withstand?
I think at 200° Celsius (392°Fahrenheit) it is too warm and the strip melts.


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05-27-2020, 12:52 PM (This post was last modified: 05-27-2020 03:50 PM by Gene.)
Post: #13
RE: Hp 50g vertical display problem
I set my soldering iron to about 350-400F and used an 1/8" thick piece of silicone tubing as the insulator. I think the temp on the other side of the silicon was around 180-200F. (Used a laser temp gun to measure the surface temperature) This temperature combined with about 2-seconds of moderate pressure, reconnected glue bond and all 10 of my vertical lines.

I've only worked with the connections you have labeled as "red".
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