checking voltage

[slaghammer]

 You say. If in doubt check voltage. I understand that all meters are different so if a part in a circuit is supposed to be 4v at what
plus and minus point would you call it bad.
Thanks. Leo

[SL4P]

+/- 5% max, then start to ask why... unless the supply is marked as being better than 5%

[picandmix]

If you are concerned about the accuracy of your meter, then get one of the cheap 5v volt reference diodes like a LM4040 or one of the many similar devices to see how good it really is.
Some meters do have internal adjusters to you can recalibrate for that particular range.