General bootleg PCB voltages?

[Uroko Sakanabito]

Can we collect some voltage values for bootleg PCBs?
The previous owner of my Xaind Sleena did mention something around 5,4v.
I do not want to harm anything but it looks like the sound starts to work around 5,10 and gets normal loud around 5,25
(I loose around 0.04 due to the harness)

Thank you!

 

[ekorz]

https://www.arcade-projects.com/threads/best-voltage-settings-for-these-games.19117/

By the way, audio is not on the 5v line, it’s on the 12v line. Turning up 5v is never the answer, if I had to guess the previous owner’s power supply probably needs recapping. Grab a multimeter and check your 12v if you have the same issue.

5v 5.00v 5.00000v. That’s it. 5v logic chips want 5.0000000000v. Measure at the chip. If you’re measuring upstream you get a little bit of drop but the fact remains the chips want 5v.

 

[Uroko Sakanabito]

Hmh, now i´m even more confused. The seller simply told me the game had to be set on 5,4 in his Astro City.
Some of his bootlegs even had instructions on it saying stuff like set to 5.2, 5.4 etc...

WIll measure my 12v now, one sec...
EDIT; All fine also the board is fully recapped

 

[ekorz]

What makes more sense, the board wants 5v and the owner didn’t know how to measure voltages correctly? Or you have the only set of 5v logic chips that operate perfectly at 5.4v?

More than likely the owner measured his psu without any load, at 5.4v, then plugged in the pcb. That’s now how you do it. Watch the video on the other thread. Always measure voltage under load.

 

[Uroko Sakanabito]

Ok, so in the end i crank it up until i get 5v on the chips that need it?
I will do what you suggest to do in your video and report.
Thanks again!

PS; A lot of people told me bootlegs simply need more...
so confusing

 

[ekorz]

Nothing special about a bootleg. It’s just logic chips, rom, ram, cpu etc. maybe cheaper traces? If a board itself has a voltage drop between the first and the farthest chips, you may need to increase voltage a tad to compensate.

Look up the data sheet on a chip in the front of the pcb, near the jamma edge. Confirm with a multimeter what pin is 5v and which is ground. Do the same for a chip on another board stack, or at the rear of the pcb, etc (far from the first). Then plug the board in and see if there is a great difference.

The only thing I can tell you is that both want 5v exactly so if the rear chip is only seeing 4.5v due to the drop within the pcb itself, you need to compensate for that. But it’s not about randomly selecting an increased voltage and thinking it’s right. Some folks will run another power line to the rear. but it’s so rare, and usually due to some other obvious issue like trace corrosion.

 

[Uroko Sakanabito]

Thank you again!

Did plug it in for measurement and it runs fine out of the box with full sound on 5.05...
Are there any idiot things affecting the voltage line?
Like dirt on the connectors or something else i miss?

 

[ekorz]

Are there any idiot things affecting the voltage line?
Like dirt on the connectors or something else i miss?

Only idiots who set their 5v voltage to 5.4v

Yes, damage from capacitor leaks can rot traces. Damaged components could be impacting voltage beyond them. Previous poor repairs could impact things too.

Dirt on the connector or jamma edge can impede conductivity at the connection point, but you can clean those.