Photos of both sides including this crystal oscillator?

Cheers,

The value on my board for this crystal is : TQ14.318B. Presumably 14.318 MHz ?

By the way, check the resistor value (in ohms) of your caps. I found out that even caps that look completely fine can have gone bad. You will read a small value or even 0 if the cap has shorted.

i wonder why the crystal was replaced on my board then.

in this motherboard the crystal is 14.3F2LB .

i found nothing on google about it.

only one post from a guy saying the crystal from an abit NF7-S dropped and it was a 14.3F2LB

so strange, im missing like 0.018 then?

Maybe factory rework after realising they built a board with a defective crystal?
Just a guess.

14.3818 MHz crystal is typically standard tight-coupled to a clock generator IC next to crystal.

Cheers,

Does the crystal say anything else on it? It's literally just "14.3F2LB"? If there's something else it could give a clue of who made it and maybe lead to a datasheet.

A crystal of 14.31818MHz (does it repeat more than that? I don't remember) is used on pretty much every motherboard. If somebody found the same part on an NF7-S from factory then I think that reinforces the assumption it's probably the correct standard frequency (so not a careless substitution).
I think that frequency is exactly 4x the NTSC color subcarrier frequency (which is why it has such an oddly specific value). NTSC isn't relevant to a motherboard but I think those particular crystals were chosen because they were common and cheap.

Have you tested the board? Somebody must have thought the crystal had failed.

From Stackexchange ( https://electronics.stackexchange.com/questio … ut-14-31818-mhz )

It is exactly 4× the NTSC color-burst frequency of 3.579545 MHz. Since it is (well, used to be) used in huge quantities in comme […]
Show full quote

It is exactly 4× the NTSC color-burst frequency of 3.579545 MHz. Since it is (well, used to be) used in huge quantities in commercial color TV sets, it is both commonly available, and particularly useful when you want to generate a signal to be displayed on such a TV.
answered Jul 31 '16 at 14:07
Dave Tweed

The exact frequency for the NTSC color burst is 30 frames/sec x 525 lines/frame x 455/2 cycles/line / 1.001 (a correction factor that avoids a problem) = 3579545.4545... cycles/second. I don't remember the precise reason the correction factor is needed, but you can probably look it up. I think it had something to do with having the field rate (59.94 Hz) NOT precisely locked to the power line frequency. – Dave Tweed Jul 31 '16 at 14:21

For anybody else looking, the factor of 1.001 looks like it is present to prevent the sound carrier and video carrier from having similar frequencies, which could cause video artifacts. en.wikipedia.org/wiki/NTSC#Color_encoding – Eldritch Cheese Jul 31 '16 at 15:00

Kind of wild the hoops that must have been jumped through to generate all the other frequencies computers need from that specific original frequency, just because the supplies were there. To be fair, even now, looking on Farnell, there's 1 crystal available at 14MHz and 139 at 14.31818 (plus 7 at 14.318). Then there's 216 at 14.7456MHz, apparently useful for 115200 baud serial.

Reason for 14.3818 was IBM PC used it to generate everything including composite output through a CGA card (no crystal on card itself) from it.

Also 14.3818 had roots in original TV ntsc. And another reason for this:
https://retrocomputing.stackexchange.com/ques … -4-77-mhz/14098

Cheers,

SETBLASTER wrote on 2021-03-24, 19:45:

i wonder why the crystal was replaced on my board then. […]
Show full quote

i wonder why the crystal was replaced on my board then.

in this motherboard the crystal is 14.3F2LB .

i found nothing on google about it.

only one post from a guy saying the crystal from an abit NF7-S dropped and it was a 14.3F2LB

so strange, im missing like 0.018 then?

If it says 14.3F2LB , I'm 99% sure it's rated at 14.318MHz, so you're fine. Manufacturers just name them differently (with their own naming scheme and such).
Why does it have flux on the pins, who knows.