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Sanwa PM1745 screen brightness fades in and out and what do these other pots do?

Posted: September 11th, 2019, 2:33 am
by Darklightjg1
Hi,

I figured I'd play with it for a while before asking about this since it took almost a year just to get an image in the first place. So the game is technically operational, but I have to resolve this eventually to make it truly enjoyable: The image on my monitor has this behavior where if the background is dark (like in the test menus or a night-time themed stage in a game), then the image automatically fades to be darker and it becomes really hard to see anything. I usually have to turn the lights off to see it in this case. Then when the background is brighter (like a sky blue stage in a game or something), the image will come back to be a little brighter, but it's still dimmer than most other arcade monitors I've seen in action (probably about 60-80% of what you may expect as a ballpark range). Not sure if you can tell that it's not that bright (but still visible) just from these pics, but I don't think the glare from the room's light would be as prominent on other monitors as an example. There are 3 with lights on and two with lights off:



The brightness pot was already as high as it can go on the remote board and there is no contrast setting on there. These are the pots on the remote board:

R. Gain, G. Gain, B. Gain, Bright, H. Size, H. Hold, H. Posi, V. Size, V. Hold, V. Posi


I think those are pretty much adjusted to where they need to be. I asked someone at a tournament who owns and provides a lot of cabs about it and he said to check for extra pots on the chassis and I'm just now noticing some... but I don't know what they do and one (H. Sub Hold) seems to have some substance on it to try and keep it in place, so I wanted to ask about them here before messing with it to see if anyone knows what each one is for:

R. BLK, G. BLK, B. BLK, Phase, PCC, H. Sub Hold, V. Lin

Can anyone tell me what each of those pots are for? Some of them were marked with a red marker line by someone to remember the default setting I guess, so I went ahead and marked the others as well.


...there's one more on the other side of the chassis that's really hard to get to (I can't even mark it). There's a metal bracket surrounding most of the parts in that section including the flyback. It's not labeled like the rest and that's the one that's really plastered down so it doesn't move. I assume that one has something to do with b + voltage and it really should only touched as a last resort.

Re: Sanwa PM1745 screen brightness fades in and out and what do these other pots do?

Posted: September 11th, 2019, 12:27 pm
by nem
Don't mess with the B+ pot.

The ones you want to adjust are R. Gain, G. Gain, B. Gain & Bright on the remote, R. BLK, G. BLK & B. BLK on the chassis, and the screen pot on the flyback. All the other pots are for adjusting sync and geometry.

Instructions are on the wiki:

https://wiki.arcadeotaku.com/w/How_to_C ... Brightness

The BLK pots are the cutoffs.