it's going to be hard to diagnose without knowing more about... well... everything.
where are you located? north america? south america? china? Europe? Australia?
where did this TV come from? local? imported? USA? Europe? Japan?
what is this TV's normal native signal format? PAL/NTSC/SECAM?
can you switch formats though tv's menu or other such setting?
what resolution are you trying to feed in? is the TV capable of such a resolution? is it too high? is it too low?
what adapter or cable are you using?
what are its capabilities?
is there any configuration that needs to be done to it?
scart can be notoriously difficult to get working properly, and it usually is due to region incompatibilities (50 vs 60 hz signal rates in NTSC vs PAL regions) tv's with specific input requirements (only being able to accept specific types of sync signals) and the "automatic" signal sourcing and configuration by the host device by having specific voltages on specific pins (like pin 8 and pin 16) there may also be incompatibilities depending on the specific revision of scart your TV has and possibly how many scart ports it has. one or more may not be capable of certain resolutions or video signals or sync signals depending on which it has... (as well as a possible difference in capabilities of the various scart ports (if it has multiple, which is not in your case anyway...but i include it for the sake of completion)) not to mention the half dozen types of cables there are and that are meant to be used depending on what kind of connection you are making.) to add even MORE convolution, a tv from japan (even though it has the same 21 pin connector as SCART) has it's own version called JP-21 with it's own pinout. This format was abandoned around 2003 (the same year as your TV's production) so it's not really common.(since your image is black and white and not "red", which is a typical issue when using a regular scart and cable with a JP-21 port... this is also not the case for your issue... but i also include this for the sake of completion)
i guess the first thing for you to do is start at the start of the signal and make sure your computer is outputting the proper resolution and frequency that your TV is capable of...and either switching the signal or your TV settings to match each other (tv service menu?)... as well as the capabilities of the scart cable/adapter or whatever.
(so ntsc/pal 50hz/60hz etc. and so on and so forth.) as long as all the signalling matches appropriately for what the signal is and the scart is telling the TV (via it's config voltages on the 8 and 16 pins), it should display it properly. Pin 8, the switch signal pin, carries a DC voltage from the source that indicates the type of video present.
typically for the switching signals...
for pin 8...
0 V–2 V means no signal, or internal bypass
4.5 V–7 V (usually 6 V) means a widescreen (16:9) signal
9.5 V–12 V (usually 12 V) means 4:3 signal
so you should have 12v on pin 8 to force the tv input to 4:3 mode since your TV is 4:3 format
for Pin 16, (the blanking signal pin), carries a signal from the source that indicates that the signal is either RGB or composite.
0 V–0.4 V means composite.
1 V–3 V (nominal 1 V) means RGB only.
i'm unsure if having 5v on this pin, as you've indicated, has any negative repercussions.. probably not... but who knows with regard to you particular tv.
your cable or adapter you have should have a circuit to combine the sync signals from your VGA input (Combine RGBHV to RGBs) since the SCART protocol does not support separated sync, only combined or "composite" sync which is a horizontal and vertical sync in one signal. and example is shown here:
https://ultimatemister.com/product/ultimate-vga-to-scart/hope this helps