(Topic ID: 201028)

WPC logic circuit running at 5.75 volts

By arolden

6 years ago



Topic Stats

  • 3 posts
  • 2 Pinsiders participating
  • Latest reply 6 years ago by arolden
  • No one calls this topic a favorite

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#1 6 years ago

Hi all.

After having some issues with resets on my JD I reflowed some solder joints on the power driver board for J101-3, fuse 113 and the LM323K regulator.

Now the resets have stopped but I am reading 5.75 volts at TP2. Out of interest, I tested the TP2 voltage on my DM. It is also high at 5.75.

The rest of my games are at 5 or below, as is normal.

Are these voltages too high? Will they cause any damage? If so, where should I look to rectify? The boards are clean with no hacks. The games play fine otherwise.

#2 6 years ago

The regulator output should be 4.75 to 5.25 volts. A higher voltage is out of tolerance of the part but not by much.
A typical source for a bit higher than normal voltage out of an LM323K is resistance between the parts ground connection (case) and board ground. Just a couple ohms will make a big difference so make sure you have a really good connection there.
Also, check to see if somebody modified your board in the past and intentionally put a resistor in there to pull up the output voltage.

5.75 will not cause damage as most parts are rated at a Vmax of 7 volts. That extra half volt won't hurt anything.

#3 6 years ago

I checked the voltages again today and they were at 5.38. Still a bit high, but better. The connection to the regulator case and ground is good - only 0.05 ohm resistance. No resistors anywhere they shouldn't be.

I think I will leave it be for now. 5.38 is better than 5.7.

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