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Blurry display

DMM6500 6½-Digit Touchscreen Multimeter
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nanofo
Posts: 1
Joined: August 14th, 2018, 10:42 am
Country: Sweden

Blurry display

Post by nanofo » August 15th, 2018, 10:26 am

Hi,

I have a problem with the display of my new DMM6500. It is blurry. Please see the attached photograph,
as shows that the X grid lines are double. Everything on the display has an "out of focus" effect, especially
if viewed from a 12 o'clock angle.

Is something wrong with the display ? I have never seen this before on a TFT display.

grid.jpg
grid.jpg (1.34 MiB) Viewed 5399 times

Brad O
Keithley
Keithley
Posts: 29
Joined: February 3rd, 2018, 10:43 am
Country: United States

Re: Blurry display

Post by Brad O » August 15th, 2018, 2:16 pm

Hi,

The display sometimes has an envelope of angles (10-15 degrees above or below the horizontal) where slight doubling occurs like your - shows, though yours does seem extreme. This is caused by internal reflections from the TFT and touch screen layers.

There's a couple options:
- If you think your doubling is excessive (It seems it might be from your photo), contact your Keithley rep or visit https://www.tek.com/repair to see about a warranty repair. It's possible the display was damaged somehow. In particular, exposure to excessive heat would increase the prominence of this doubling.
- If you haven't already, consider using or collapsing the feet of the DMM6500. It is usually a very tight envelope of angles where this doubling occurs, so changing your natural viewing angle of the instrument, even slightly, may clear the display up for you.

Pinörkel
Posts: 2
Joined: December 31st, 2020, 6:57 am
Country: Germany

Re: Blurry display

Post by Pinörkel » December 31st, 2020, 7:45 am

Hello,
I just got a DMM6500 and one of the first things I noticed was an issue with very pronounced screen image doubling. On my unit it occurs when viewing the screen in a downward direction, starting at approximately 10° up to 90°, so using the feet does not make a difference. The unit is positioned on my desk in an arms length distance what should be one of the most common viewing conditions. The screen doubling is accompanied by a pronounced loss of contrast for that viewing direction which both makes small text output very difficult to read and leaves me with a headache after 30 minutes of intense use. When viewing the screen from straight on or from below, the screen doubling does not occur and the contrast does not drop. I can not remember to have observed screen doubling or contrast issues on any small format LCD touch display before, neither with capacitive nor with resistive touch technology and especially not at this price point. At first, I suspected the screen may be missing an anti-reflective coating on some of its inner layers combined with an unusually big distance between the display and the touch layer. This does, however, not explain why the issue does not occur for upward viewing directions. Maybe the DMM6500 is optimized only for being viewed standing on a shelf above head height?

Consequently, I contacted my dealer and got offered a refund or an exchange of the unit. However, I cannot judge whether the IMHO very poor screen quality on my unit has to be considered normal or if I got a particularly bad device and a replacement might actually bring an improvement. It would be nice, if I could get some help on this based on the following attached images (if possible):

Pronounced vertical doubling for downwards viewing directions in a direct comparison with viewing the screen from straight on from an upwards viewing direction. All three images have been taken using the exact same camera settings.
DMM6500_screen_quality_0.jpg
DMM6500_screen_quality_0.jpg (456.68 KiB) Viewed 113 times

Pronounced vertical doubling and a strong loss of contrast on colored text.
DMM6500_screen_quality_1.jpg
DMM6500_screen_quality_1.jpg (478.06 KiB) Viewed 113 times

Vertical doubling with simultaneous visibility of the front panel to rule out issues with the photographic setup.
DMM6500_screen_quality_3.jpg
DMM6500_screen_quality_3.jpg (151.77 KiB) Viewed 113 times
Kind Regards

Andrea C
Keithley Applications
Keithley Applications
Posts: 1514
Joined: October 15th, 2010, 10:35 am
Country: United States
Contact:

Re: Blurry display

Post by Andrea C » January 5th, 2021, 10:18 am

Based on your photos, I'd take the exchange.

Pinörkel
Posts: 2
Joined: December 31st, 2020, 6:57 am
Country: Germany

Re: Blurry display

Post by Pinörkel » January 6th, 2021, 3:34 pm

Thank you for the reply and the assessment of the photos. I will then initiate an exchange of the device.

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