Hi all, I've got a weird video problem, perhaps one of you has seen before or could help with.
I've got an Arcade Legends cabinet with Neotec S500 CRT monitor.
The picture is just fine except when playing vertical games. For instance, Ms. Pac-Man and Galaga have vertical orientation and the scores and upper half of the screen are jittery. UPDATE - I'm not sure what I did, but now the jittery portion is middle to lower part of the screen. The scores are now fine. Ms. Pac-Man isn't really playable it's so bad. Frogger is another that's affected, and a popular game.
This cabinet is original Arcade Legends, but hard drive replaced with Ultracade with 240 games. No dongle. Parallel port turned off. If I'm not mistaken this enables CGA only mode to the monitor.
In display settings (in Ultracade test mode) you can turn ON CGA interlace and adjust anywhere from 1-126? I believe this only for using a VGA monitor, but thought I'd try it. I've tried several numbers from 1 to 30 to 50 to 120 and this setting doesn't seem to help. It only makes the screen jittery during the demo and game select screens. I'm pretty sure it's supposed to be OFF with this monitor (99% sure it's CGA).
Every single electrolytic capacitor has been replaced, about 60 of them. It was quite a job, but the picture is great! I think every horizontal game is perfect, no jitter at all. It's only when playing a vertical game.
Not sure what to try next, but I guess I'm going to try some pots on the main monitor board. There's a couple not labeled, near the sync sections. I can't find the correct manual or schematic for this model monitor. UPDATE: I have now tweaked every pot and have a good idea of what they all do. I can't make any of them adjust out this problem though. If I mess with x-ray protection R429 or B+ R111 it just shuts down.
Neotec model S500 manufactured Dec. 2005.
Thanks in advance to anyone with any insight.
UPDATE: Everything looks very similar to a NT-2700, so I've taken readings based on the schematic for that model. Voltage readings :
D106 = 117.5 VDC
D107 = 22.28 VDC
D109 = 117.5 VDC
R130 = 11.67 VDC
TP near x-ray pot = 7.72 VDC
No scope available to test FBT#9
If this model is similar to NT-2700 then my B+ is high (should be 100 +/- .5 VDC), D107 is low (should be 26.5), D109 is low (should be 140), and the reading at R130 is actually within spec (12v +/- .5).
I know that adjusting R111 will raise the B+, but how would I adjust the other voltages?
Could these have anything to do with the jittery picture which is only on vertically oriented games?
Anyone have the correct schematics?!!