Measuring Voltage on Jamma

[Dreamstate]

So, I am trying to get the voltage just right on my ST-V Multi with LCD. The board seems to work great without the LCD, but wants to lockup randomly in games when I do use it. I think the added draw of power from the LCD is causing the issue. Now, on to the real question. If I remove the Board from the Jamma connector, I get around 5.2V. When the board is plugged in, I get exactly 5V. At first I lowered the Jamma only power down to 5ish thinking I was sending too much power, but the board would barely boot before locking up. Where it is now, it runs for 5-10 minutes before locking up. I want to increase the Voltage a bit more, but I want to make sure I am supposed to be measuring when the board is attached and not when there is no load. Advice?

 

[Mitsurugi-w]

Yes. Always measure with load. You can also test your theory by disconnecting power to your lcd. The cart will still boot the last game loaded.

 

[twistedsymphony]

yes, measure when the board is attached.

and ideally you should measure voltage on one of the chips as opposed to the edge connector.

the voltage at the edge connector will always be higher than what the chips are actually getting.

the voltage that the chips are actually getting is really the only voltage that matters.

I usually adjust for 5.05 as measured on the chips. Or in cases where I can't 5.10 at the power connectors/JAMMA edge while connected.

 

[Dreamstate]

Perfect. That was just the advice I was looking for. I know just where to test the power on the board since I needed it for the Multi-Board LCD.

Thanks!

 

[rewrite]

yes, measure when the board is attached.

and ideally you should measure voltage on one of the chips as opposed to the edge connector.

the voltage at the edge connector will always be higher than what the chips are actually getting.

the voltage that the chips are actually getting is really the only voltage that matters.

I usually adjust for 5.05 as measured on the chips. Or in cases where I can't 5.10 at the power connectors/JAMMA edge while connected.

I think it's worth saying that you should check both at the edge connector and a chip. If only because if the board is dropping an inordinate amount of power due to some fault or something you don't end up pumping 5.4v into it to see 5.05 on a chip, and ruin some other components in the process.

 

[Dreamstate]

Good advice. Will do.