7" 4:3 LCD that accepts 640x480 input for scope CRT replacement? - Page 1
Forum section: electronics / projects

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 21, 2021, 07:45:13 am
content: 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!

author: Miti
author_rank: Super Contributor
timestamp: November 21, 2021, 12:42:03 pm
content: All LCD modules should accept 640x480 signals, if the timing is standard. Can you check your sync timings?http://tinyvga.com/vga-timingEdit: I meant driver modules similar to KYV-N2 V2 that you mentioned.

author: PKTKS
author_rank: Super Contributor
timestamp: November 21, 2021, 01:21:51 pm
content: 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

author: coromonadalix
author_rank: Super Contributor
timestamp: November 21, 2021, 02:28:16 pm
content: 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

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 21, 2021, 02:55:37 pm
content: 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 = 59.9kHzOn 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.

author: dl6lr
author_rank: Frequent Contributor
timestamp: November 21, 2021, 03:47:03 pm
content: Quote from: TERRA Operative on November 21, 2021, 02:55:37 pmI 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".

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 21, 2021, 03:58:02 pm
content: 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.htmlThe 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).

author: coromonadalix
author_rank: Super Contributor
timestamp: November 21, 2021, 06:22:43 pm
content: strange image, seems an out of focus / convergence we could have in the past with crt tubesIs there some phase shift adjustments / convergence on your present ''non'' working kit ??

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 21, 2021, 11:37:19 pm
content: 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.

author: Miti
author_rank: Super Contributor
timestamp: November 22, 2021, 10:15:05 am
content: Quote from: TERRA Operative on November 21, 2021, 03:58:02 pmThat 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?