The picture below shows the 5Vs I'm getting. The game isn't resetting. But while my DMM reads around 4.86 V, the scope shows a close to 700 mV swing. I scoped out a couple other WPC machines and their 5V on the scope has a significantly smaller swing.
So I'm planning on getting a new LM323 (NTE931) and trying it out... unless someone says I'm going down the wrong path.
Thanks
Quoted from LTG:If your game isn't resetting, I'd leave it alone.
Good advise which I usually follow, but...
Quoted from barakandl:I would suspect the filter cap first
So I replaced C4 and the DMM reading went from 4.86 to 4.92V. The swing also reduced, but not to the level I wanted.
I discussed this with some other people and the general conclusion is that this is not something to worry about. So I'm planning on leaving it as is.
The output of a LM323K varies from component to component. I have seen some new ones put out 5.3v and other ones put out 4.7v.
4.9v is a touch low, but if you are not getting resets, don't mess with it.
4.92 should be good....Correct me if I'm wrong but the watchdog Dallas circuit resets the game if voltage drops below 4.80v I doubt you can get one in there that will be 5.0..there is like a 3-5% give on those LMK323.
There is nothing wrong with that regulator and is within spec. Voltage ripple is not caused by the regulator but by filtering caps.
If you *must* increase the voltage, insert a resistor in the regulator's ground path. Approximately every 10 ohms of resistance added to the ground path raises the output voltage by about 0.1 volts.
Thanks guys.
So talking theoretically here...
What would I need to do to reduce the point-to-point AC ripple? I have a new C4, BR2 and C5 installed and I'm seeing the image above. Ok, it got a little smaller (200 mV? I don't recall) when I replaced the C4. But it's still at least 400 mV.
The ripple is almost exactly 5 Mhz. Perhaps it's high frequency noise from somewhere else in the machine?
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Hopkins, MN