how do I adjust output voltage?

tighecg

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Hey guys. I have a mv-1 and bvm. I have pots on the rgbs lines and have been told that the output voltage should be .7 volts. I set the voltage by putting a meter on the end of the cable on each line, with the neo sitting on the screen color adjustment screen in the hardware test menu. Is this the right way to go about this? My bvm has been acting up, and I have a feeling this is the problem. Although about two years ago I had it shipped to me via ups. I have never been totally sure they didn't fuck it up. Every once in a while it would do something odd, but it has been acting up more since I hooked my neo up. Any help would be appreciated.
 

mikejmoffitt

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The closest thing is to have an all-white screen and measure that, but even then it's not really perfect. The right solution is to use an oscilloscope, and measure it while things are connected as they would be during normal use.
 

tighecg

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Thanks, I don't have access to an oscilloscope, so i'll see if I can get a static white screen somehow. I have a unibios 3.1 I have not installed, does that support pausing the game? I should search the forum for an answer to this, and i'm sure the answer is on razoolas site. As a side question, I have been waiting to install the bios, thinking about updating it. Are there enough improvements on the 3.2 to really need uprading?
 

mikejmoffitt

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Dip switch #8 will halt the game at whatever it's at. You might be able to find a game with a white screen and halt it there. I can't speak for the advantages of 3.2, you'll have to see the changelog to decide.
 

Xian Xi

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What exactly does "something odd" mean regarding the BVM? Is it rolling, flashing, clicking, waving, etc?
 

tighecg

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What exactly does "something odd" mean regarding the BVM? Is it rolling, flashing, clicking, waving, etc?

Various momentary issues. Nothing that sticks more than a split second. With the neo I started seeing what seemed to be a momentary drop in one of the colors, not always the same color. Then once I got a pretty big pop and I saw a flash of light, not an explosion, I assume something arced behind the tube.that's when I thought my voltages must be wrong. I haven't turned it on much since then. The few times I have, it seemed ok. The first time after the pop the degauss seemed kinda weak, but that is ok now also. Before the neo I would get occasional small pops,I think it happened three times total before neo. I assumed this was from dust getting in the enclosure, but the ups shipping has always been in the back off my head. Other than that, I have never noticed any of the issues you mention. I opened it up, but didn't see anything to unusual. I am an industrial maintenance electrician, so I am familiar with electronic components, but nothing like this, and zero experience working on crts.Admittedly this is too much monitor for me. I am not the videophile that can truly appreciate this unit, but it was the right price, at the right time.
 

tighecg

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As far as the colors dropping,I checked my connections and they are good. Assembly and fabrication I can handle like a champ.not bragging.....Ok maybe a little.
 

tighecg

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Dip switch #8 will halt the game at whatever it's at. You might be able to find a game with a white screen and halt it there. I can't speak for the advantages of 3.2, you'll have to see the changelog to decide.

Thanks Mike, this should be very helpful. Now I need to find a game with the white screen.
 

tighecg

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Try adding 75 ohm pull down resistors on each of the RGB lines.

with the pots(variable resistors), this shouldn't be required as I can adjust the resistance. Am I missing something as to why this would be needed. I could put my meter on the pots and set them to 75 ohm, Is that the magic number for the .7 volts?
 

Xian Xi

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with the pots(variable resistors), this shouldn't be required as I can adjust the resistance. Am I missing something as to why this would be needed. I could put my meter on the pots and set them to 75 ohm, Is that the magic number for the .7 volts?

Inline and pulldown are two totally different things.
 

Xian Xi

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In case it wasn't clear or if some didn't know, pull down resistors will drop the voltage better than inline resistors and also some TVs/Monitors require a 75 ohm termination.
 

shadowkn55

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with the pots(variable resistors), this shouldn't be required as I can adjust the resistance. Am I missing something as to why this would be needed. I could put my meter on the pots and set them to 75 ohm, Is that the magic number for the .7 volts?

Putting a resistor in series vs. a pulldown to ground do different things. Also, 0.7v is a peak to peak rating (vpp), so the scale isn't necessarily 0v-0.7v.

Found a link regarding the bvm and pulldown resistors.

http://www.neo-geo.com/forums/showt...-both-look-terrible-on-Sony-BVM-20F1E-Monitor
 
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tighecg

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Ahh, I see now. Remove the pots and add the pull downs. If I were to leave the pots in for some extra color control would this cause any issues? A/V electronics is a new part of the electrical field for me, electronics(not electrical) theory and engineering are not my strong suit.

Any other ideas as to what might be going on with the bvm? Like I said, I'm not totally sure the neo is solely responsible for my issues. Any suggestions for things I should be looking at closer in the bvm?
 
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Xian Xi

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Yes, leave the pots for tuning the picture but add the pull downs.
 

tighecg

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Ok, I have been thinking about this, which usually gets me in trouble, but a potentiometer is grounded. It is different from a simple in line resistor, or variable resistor. Wouldn't this accomplish the same thing as the pull down? I'm not trying to talk down to you, or be an asshole, just explaining my thought. Fudoh over at schmups told me to add these. I don't know how you guys feel about him, or if you even know of him, but he seems like a pretty sharp guy.
 

tighecg

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wasn't trying to be a jerk guys, I just want to correct my thinking, would like to understand why I'm doing what I'm doing. I get the vo;ltage thing and the efficiency of it, just wondering about the pot ground versus the pull down.
 

shadowkn55

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Ok, I have been thinking about this, which usually gets me in trouble, but a potentiometer is grounded. It is different from a simple in line resistor, or variable resistor. Wouldn't this accomplish the same thing as the pull down? I'm not trying to talk down to you, or be an asshole, just explaining my thought. Fudoh over at schmups told me to add these. I don't know how you guys feel about him, or if you even know of him, but he seems like a pretty sharp guy.

It's not the same thing. Why don't you actually try some of the suggestions put forth and report back with the results?
 

tighecg

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I get it now. I did some research and I figured out why I was not seeing the need for the pull downs. They don't really have anything to do with the absolute peaks of my output, but they will keep a tighter tolerance around the low end of the cycles. that coupled with the white screen adjustment should resolve the issue I believe is happening and even improve the performance of my set up. I will add the pull downs, but in this whole process I have also figured out I have two shitty pots in the mix. I'm going to order some new pots and redo the whole thing, so it may take some time to get back with the results. I went back and discussed the issue with Fudoh also and I want thank all four of you.

It's not the same thing. Why don't you actually try some of the suggestions put forth and report back with the results?

I was initially really pissed about this comment. I discussed the whole situation with a coworker, who also had some good input on the problem, and he said I was behaving like a toddler who constantly asks questions one right after another, never putting any effort into really trying to understand. Any father can tell you how annoying this is. As soon as he said it, everything turned black and white as far as my behavior on this forum, and others. now I'm pissed at him for proving to me beyond a shadow of doubt why I was being an ass. But I gotta thank him too for correcting me. Not only did I learn a lot about electronics, but I got a psychology lesson also.

Thanks from the annoying toddler.
 

tighecg

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Ok, so I got new pots and put in the pull downs. Everything seems pretty good now as far as stability. I haven't been able to do a marathon test yet. But I played through all of metal slug x with no issues.for some reason before,I could only make it half to three quarters of the way through and I would have issues. Right after msx, I put in baseball stars 2, and got to about the sixth inning and had a little split second flicker. Finished the game with no issues. The day after played last resort for about a hour with no problems.

Now everything seems pretty dark to me though. I really don't wanna crank up the pots again, and I can't seem to get it just right with the settings on bvm. Should I be worried about this, or do you guys think I'm just used to playing with the output cranked up to high?

Thanks for the help guys.
 

tighecg

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If you put both pots and pulldowns, don't ground the pot.

Thanks xian, everything looks great now. I still haven't been able to sit down for a long session yet, but other than that one flicker during baseball stars 2, I haven't had any of the original issues either. Great help, thanks again to everyone.
 
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