Author Topic: 7" 4:3 LCD that accepts 640x480 input for scope CRT replacement?  (Read 1519 times)

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Offline TERRA OperativeTopic starter

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7" 4:3 LCD that accepts 640x480 input for scope CRT replacement?
« on: November 21, 2021, 07:45:13 am »
I have a Tektronix TDS744A here with the NuColor CRT screen that is faulty.
I am currently in the process of converting it to LCD, but I'm having a bit of trouble finding an 800x600 4:3 LCD screen that accepts a 640x480 signal (Native resolution for these scopes).

I already bought a panel with a KYV-N2 V2 driver PCB, but it doesn't work with 640x480 input resolution. (The colours are out of phase and distorted).

Has anyone got any 7 inch 800x600 panels working with a 640x480 input signal and if so, can you let me know the model number of the PCB you used?


Thanks!
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Offline Miti

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Re: 7" 4:3 LCD that accepts 640x480 input for scope CRT replacement?
« Reply #1 on: November 21, 2021, 12:42:03 pm »
All LCD modules should accept 640x480 signals, if the timing is standard. Can you check your sync timings?

http://tinyvga.com/vga-timing

Edit: I meant driver modules similar to KYV-N2 V2 that you mentioned.
« Last Edit: November 21, 2021, 01:45:11 pm by Miti »
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Offline PKTKS

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Re: 7" 4:3 LCD that accepts 640x480 input for scope CRT replacement?
« Reply #2 on: November 21, 2021, 01:21:51 pm »
I have one of those handy dongles....
For checking some standard resolutions ....

They operate with a single 9V bat and can output VGA just fine.
Very handy in such cases...

Paul
 

Offline coromonadalix

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Re: 7" 4:3 LCD that accepts 640x480 input for scope CRT replacement?
« Reply #3 on: November 21, 2021, 02:28:16 pm »
a 800x600 panel would display a 640x480, the image would be smaller in it IE : having a border of somekind  ... but not distorted,   maybe your source signal is incomplete or not okay in a way ???
 

Offline TERRA OperativeTopic starter

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Re: 7" 4:3 LCD that accepts 640x480 input for scope CRT replacement?
« Reply #4 on: November 21, 2021, 02:55:37 pm »
This is the image I got at 640x480 from the VGA port at the back of the scope connected to the 800x600 7" screen I have (attached below).
My PC monitor says the signal is 640x480, fH = 31.3kHz, fV = 59.9kHz

On my other small 800x480 LCD screen, I got a perfect image (I can display it basically pixel perfect with black bars on the sides), but while the panel fits in the available space in the scope, the viewable image is far too small.
I need the screen to be as close to 146mm wide (and 113.5mm tall) as possible, but with the 800x480 screen, I will only get 89mm tall by 118mm wide.

I don't mind having the image scaled up to 800x600, which is what the screen in the image below tried to do, just too poorly to be useable.
Where does all this test equipment keep coming from?!?

https://www.youtube.com/NearFarMedia/
 

Offline dl6lr

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Re: 7" 4:3 LCD that accepts 640x480 input for scope CRT replacement?
« Reply #5 on: November 21, 2021, 03:47:03 pm »
I don't mind having the image scaled up to 800x600, which is what the screen in the image below tried to do, just too poorly to be useable.

I bought a Wincor BA80 800x600 ECR display, which scales up really nicely, but it is too large for you as the display is 8.4".
 

Offline TERRA OperativeTopic starter

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Re: 7" 4:3 LCD that accepts 640x480 input for scope CRT replacement?
« Reply #6 on: November 21, 2021, 03:58:02 pm »
Well, I have found this one. A little more than I wanted to spend, but not outside the realm of affordability.
The viewable screen size isn't tooooo much smaller than the old CRT, and being 640x480 means it'll be a crispy sharp display.

https://www.aliexpress.com/item/1005001526578386.html

The trick will be finding out if it can switch on automatically when power is applied, but if not, it will be relatively simple to simulate a button press with a mosfet or relay or something when power is applied to the voltage regulator circuit I'm designing (Gotta go from 25V to 12V).
« Last Edit: November 21, 2021, 04:00:04 pm by TERRA Operative »
Where does all this test equipment keep coming from?!?

https://www.youtube.com/NearFarMedia/
 
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Offline coromonadalix

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Re: 7" 4:3 LCD that accepts 640x480 input for scope CRT replacement?
« Reply #7 on: November 21, 2021, 06:22:43 pm »
strange image, seems an out of focus / convergence we could have in the past with crt tubes ???

Is there some phase shift adjustments / convergence   on your present ''non'' working kit ??
 

Offline TERRA OperativeTopic starter

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Re: 7" 4:3 LCD that accepts 640x480 input for scope CRT replacement?
« Reply #8 on: November 21, 2021, 11:37:19 pm »
First thing I checked. :)
There is two menu options of which one icon seems to be the interesting stuff, but I am unable to access them, so no adjustments beyond brightness/contrast and centering of the image are available.
Where does all this test equipment keep coming from?!?

https://www.youtube.com/NearFarMedia/
 

Offline Miti

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Re: 7" 4:3 LCD that accepts 640x480 input for scope CRT replacement?
« Reply #9 on: November 22, 2021, 10:15:05 am »
Well, I have found this one. A little more than I wanted to spend, but not outside the realm of affordability.
The viewable screen size isn't tooooo much smaller than the old CRT, and being 640x480 means it'll be a crispy sharp display.

https://www.aliexpress.com/item/1005001526578386.html

The trick will be finding out if it can switch on automatically when power is applied, but if not, it will be relatively simple to simulate a button press with a mosfet or relay or something when power is applied to the voltage regulator circuit I'm designing (Gotta go from 25V to 12V).

That may not solve your problem. By my calculations, the horizontal frequency should be 31.47 KHz, yours is 31.3, you say. Some displays may be ok with it, some not. If you connect it to a computer and set the output to 640x480@60Hz, what do you see?
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