UGV Ultimate Gated Video Board (this archival information is for an older version)
Go to: NEW and Improved UGV-II Version
NTSC Users: One Simple Modification Required on the Atari Motherboard...
Go to: NEW and Improved UGV-II Version
NTSC Users: One Simple Modification Required on the Atari Motherboard...
W2 Jumper
Atari for reasons I have yet to discover, decided to put a jumper from the primary crystal oscillator's output over to GTIA's PAL Color Burst Input (pin 16). On an NTSC machine this jumper is normally installed, which is bad news for the PAL detection input on the V-Gate chip. What it means is that the V-Gate chip will think it's in a PAL machine even though it's actually an NTSC. This will have the end result of causing a blue vertical stripe on the left side of the screen, and a red stripe on the right side whenever V-Gate is enabled.
The fix is easy, and amounts to either cutting one lead on the jumper or removing it all together. in either case the jumper was never required, and there will be no detrimental effect to leave it out permanently.
On all XL and XE systems it's identified as 'W2' on the motherboard's silk screen, and is either located close to the main oscillator and crystal on an XL unit, or close to the unpopulated PAL Color Burst oscillator circuit where the 74LS74 would normally be located if it were an XE PAL machine. The 74LS74 is designated as U21 on the 65XE and 130XE, or as U10 on an XEGS.
The 1200XL is the exception to this rule, and although it too has a place for a jumper (designated as 'W10' instead), it apparently was never installed in most, or maybe all of those machines. So no modification is likely to be needed. And lastly the 400/800 series didn't even have a jumper and left the NTSC GTIA pin 16 unconnected, which is what we want.
The fix is easy, and amounts to either cutting one lead on the jumper or removing it all together. in either case the jumper was never required, and there will be no detrimental effect to leave it out permanently.
On all XL and XE systems it's identified as 'W2' on the motherboard's silk screen, and is either located close to the main oscillator and crystal on an XL unit, or close to the unpopulated PAL Color Burst oscillator circuit where the 74LS74 would normally be located if it were an XE PAL machine. The 74LS74 is designated as U21 on the 65XE and 130XE, or as U10 on an XEGS.
The 1200XL is the exception to this rule, and although it too has a place for a jumper (designated as 'W10' instead), it apparently was never installed in most, or maybe all of those machines. So no modification is likely to be needed. And lastly the 400/800 series didn't even have a jumper and left the NTSC GTIA pin 16 unconnected, which is what we want.
Original Older UGV Video Board Manufacturing Files
NOTE: The Value of R16 was Updated on 3/5/2023
|
Header J1 - Video Output 
CVBS = Composite Video Blanking & Sync
Header J2 - ICSP
If the RF Channel Select switch on the Atari is no longer needed, it can be used to disable and enable V-Gate when connected to PDAT. DipSwitch SW1 - Video Data Level Adjustment 
Allows adjustment for video converters. 660mv is the Standard Video Output Level, bringing it just a tad under 1 Vpp when the Sync gets added back into the equation. | ||||||||||||||
