Testing computer PSU's, non-standard arcade PSUs

ShmengeTravel

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Recently after my Virtua Fighter and MK scare, I decided to check the voltages of all my arcades. However, the rest of the games in my arcade (which are quite a lot), all use the newer, computer-like power supplies, and I don't know how to test the voltage on them under load. My UMK3, VF, VF2, VF4E, even my SF2CE cabinet has a computer style PSU. How do you test these things under load? I want to make sure I'm not over-juicing anything like I kindasorta did with my MK. :(

Thanks in advance!
Shmenge
 

channelmaniac

Mr Neo Fix-it
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You test them by hooking them up to a board and then measuring the outputs with a meter.

If you don't have a scrap board for testing you can build a test jig with large wattage resistors to put a sufficient load on the power supply.

Don't forget you really aren't wanting to test just the DC voltage. You want to measure the noise on the power supply output as well. That can be best done with an oscilloscope but you can get away with using a meter on AC as well.

RJ
 

ShmengeTravel

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Well I meant like, when I test regular arcade PSU's I turn the game on, and touch the positive on the multimeter to the 5v and the negative to the GND, but what do I do for the computer-style ones if theres nothing to touch? It's hard to explain. I'm sort of new to this only because I never had to start worrying about it until obviously, things started malfunctioning. I just got done adjusting my CvS machine and so far all seems well.
 

ShmengeTravel

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ahhh, gotcha. Will do. The VF's are gonna be weird because they're not JAMMA, I should be able to figure it out because the manual does have schematics. Testing the Naomi system is going to be tough as well. The UMK3 and SF2CE I can test at the JAMMA tho.
 

channelmaniac

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You should ALWAYS test at the JAMMA edge connector or at a test point on the board and not at the power supply itself.

There are voltage losses in the wiring harnesses. If the wires are too small and you have a large board then you could be underpowering your board.

Set it for 5.1v at the JAMMA edge connector or at the board itself, not at the power supply.

RJ
 

ShmengeTravel

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Oh I see, well that would make sense. I tested the UMK3, turned out to be 4.99 which it was running fine minus the one bad rom chip its had since I got it, but even stranger is there doesn't seem to be anything to adjust the 5v rail on its PSU! The SF2HF needed to be adjusted and I think the gameplay may have gotten faster as that 5v was underpowered as well. Both were tested at the JAMMA edge with load. I'll have to re-test my CvS and MK as those were both tested at the PSU.

Edit- Just tested the CvS... at the PSU it reads 5.16, but at the jamma it reads 7.03? Can that be right? It does use the Capcom JAMMA converter so I'm not sure if that factors into anything.

Edit 2- Correction, I tested it again and it read a solid 5.0. I'm gonna up it to around 5.16 just to be safe.
 
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channelmaniac

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Not all power supplies are adjustable.

I'd even venture as far as to call the ones that are adjustable "cheap" since they don't have good enough feedback and regulation circuits to keep a steady 5v output as the current draw gets higher.

RJ
 
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