Author Topic: Scopemeter 97 poor contrast  (Read 734 times)

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Offline Denis1024

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Scopemeter 97 poor contrast
« on: November 08, 2019, 02:49:14 pm »
Hello,
I bought an old Fluke 97, but unfortunately it was down. I repaired it, one of the failures was the backlight. Now everything is fixed, but the LCD has a very poor contrast, at the limit, hard to read, even with a strong light or even with the backlight.

The pixels are not dark, but gray.
I wonder if such an LCD screen can be damaged for years?
Is there someone who owns a 97' with a good contrast?

I found this thread:
https://www.eevblog.com/forum/testgear/old-philips-fluke-97/100/

It seems that a polarizer can be damaged over the years?
Could someone confirm that?
Thanks
Denis
 

Offline rvalente

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Re: Scopemeter 97 poor contrast
« Reply #1 on: November 08, 2019, 04:25:27 pm »
Ive had this trouble with my ths720p, bad polarizer, had to replace it. The contrast is not the same as the genuine material from sharp but, is very useable.

You should post a picture but, if the screen is inverting colors from the center to the edges in a circular form, its very probable the polarizer ia bad.

check https://www.eevblog.com/forum/repair/fluke-744-display/
« Last Edit: November 09, 2019, 06:56:49 pm by rvalente »
 

Offline testpoint1

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Re: Scopemeter 97 poor contrast
« Reply #2 on: November 12, 2019, 05:38:05 am »
yes, very old, the plastic need to be replaced it.
 

Offline george.b

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Re: Scopemeter 97 poor contrast
« Reply #3 on: November 19, 2019, 12:13:33 pm »
Like rvalente said, bad polarizer. Extremely common in 90s LCDs.

I reuse polarizers from broken, modern LCD screens for repairing those with some success. The color is usually a bit off, but meh :-//
 
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Offline pocal

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Re: Scopemeter 97 poor contrast
« Reply #4 on: August 13, 2020, 10:16:24 pm »
bonjour le mien est en panne je sais pas dans quel état est l’Écran, je cherche des infos sur l'alimentation,je n'ai pas de tension nulle part sauf sur le transfo ou j'ai 20 volt et le schéma de l'alimentation est mal détaillé , je trouve les éléments sur la sérigraphie, mais sur le schéma
avez vous un schéma de l'alimentation détaillé?  merci pour la réponse 
 

Offline rvalente

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Re: Scopemeter 97 poor contrast
« Reply #5 on: August 13, 2020, 11:37:53 pm »
bonjour le mien est en panne je sais pas dans quel état est l’Écran, je cherche des infos sur l'alimentation,je n'ai pas de tension nulle part sauf sur le transfo ou j'ai 20 volt et le schéma de l'alimentation est mal détaillé , je trouve les éléments sur la sérigraphie, mais sur le schéma
avez vous un schéma de l'alimentation détaillé?  merci pour la réponse 

Altought I speak french, thats a english language forum.

Could you try better describing your troubleshooting?

https://www.cl.cam.ac.uk/manuals/pm93_95_97_fluke_93_95_97.pdf
 

Offline shakalnokturn

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Re: Scopemeter 97 poor contrast
« Reply #6 on: August 14, 2020, 06:31:00 pm »
Altought I speak french, thats a english language forum.

Could you try better describing your troubleshooting?

https://www.cl.cam.ac.uk/manuals/pm93_95_97_fluke_93_95_97.pdf

Would be worth the bother trying englische even the French is very average.
 

Offline rvalente

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Re: Scopemeter 97 poor contrast
« Reply #7 on: August 14, 2020, 09:24:19 pm »
Altought I speak french, thats a english language forum.

Could you try better describing your troubleshooting?

https://www.cl.cam.ac.uk/manuals/pm93_95_97_fluke_93_95_97.pdf

Would be worth the bother trying englische even the French is very average.

Nice, how is your portuguese? Probably better than mine...
 

Offline shakalnokturn

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Re: Scopemeter 97 poor contrast
« Reply #8 on: August 14, 2020, 09:59:21 pm »
No chance... I can hardly make any difference between Spanish and Portuguese.
I do find the Brazilian easier on the ear than the Portuguese though.
 


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