New Power Supply question

kpkube

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I got a new power supply and there is a notice that "When measuring power supply output voltage a MINIMUM 1 Amp load is required on the +5vdc" The board I have only uses +5vdc. What is the best way to measure this with the board attached and not fry the board? The power supply has a +5vdc pot on the side.
 
that just means you should have the board hooked up to get a accurate reading,

if you have a multimeter put it on DC voltage and put the black lead on the ground on the power supply and the red on the +5
 
Remember Ohm's Law!

Use a 5 ohm resistor to get 1 amp out...

P=E*I which = 5v * 1A = 5 watt

So 5 ohm at 5 watt will put a 1A load on the supply.
 
Thanks Guys.
Should I be setting this to exactly 5 volts or just slightly higher?

That really depends on the game. Some, like Q*bert, want the voltage to be a little high. It takes a huge draw. The power supply actually puts out about 5.8v, but reads about 5.1 at the chips. Others want it a little low. Take your voltage readings right at a chips, not at the connector. Start it as close to +5 as possible. Then connect it to the game and take a reading and adjust as needed by getting close to 5v at the chips. Some games will give you issues if it's too low or high, by giving you, usually, graphics errors.
 
TTL, HMOS, and your other logic runs at 5v +/- 5%.

This means it should run from 4.75 to 5.25 volts.

HOWEVER, with that said, some chips refuse to run at the lower end, others crap out towards the upper end.

An extreme would be the Sega NAOMI system. The tiny buffer chips in the cartridge like to die if you run them over 5.2 volts for very long. You'll start getting crashes, lockups, reboots, and cartridge errors.

I set power supplies to 5.1v at the board edge.
 
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