[#10]
Re: A1200 NTSC z 060 vs demoscenowe produkcje
@] SKOLMAN_MWS ˇ agrEssOr [,
post #9
PAL/NTSC 1200 motherboards are identical.. it's just a few component differences.. To turn a PAL unit to NTSC
1. Swap X1 for a 28.6363Mhz Oscillator
2. Move R245 to R246 location (This feeds NTSC color clock from Alice/Budgie to the RGB encoder)
3. Remove R202, and place a 0 Ohm at R203 (This pulls the #NTSC pin on ALICE low, and NTSC signal on the encoder High to Select NTSC in both cases)
4. Remove the Y451 (4.336Mhz Crystal) to disable the PAL burst oscilator, since this circuit's noise seems to sometimes cause a pattern on the composite output.
Side notes (Effects the composite out only. Don't have to do this, but just to be complete):
Z221 (Band Pass Filter), would also need to be changed, but have long since gone EOL, but leaving R221 & R223 (which should also be changed) at the lower value compensates for it.
R224&R225 would also need to be modifed, if the delay line is swapped, but the delay line Z222 is also long since EOL, so you also leave this is as is, the delay is a bit off, but it's really not noticable.
After you do the changes 1-4..
The system will now boot up in NTSC, the composite output will also be NTSC, and the RF modulator output will not work (you'd need to swap it for an NTSC one)
If you only do step #3 (Similar to what Gulliver is mentioning).
This is the quickest and easiest way..
You'll have the system boot up in "sorta NTSC". The RGB will function as expected in NTSC. The composite will be monochrome only, an A520 should let you have color NTSC composite. Now, because you're in NTSC with the wrong main crystal frequency. Some Genlocks will not function, and there might be problems with serial port communications and music playback on some application that don't check the crystal speed or the graphics.library "True" flags.. This is pretty much identical to the case of choosing NTSC in the startup menu..
zrodlo: http://www.amiga.org/forums/archive/index.php/t-55558.html
Tak wiec czeka cie przejscie krokow 1-4 tyle ze odwrotnie, i uzyskasz wersje PAL. banalnie proste :)