Selecting Power Supplies Last Updated on: 6/19/2013

If you don't frequent the USENET a lot, you might miss out on a lot of good information. Bob Roberts is on there all the time and is a fantastic source of good information. He is also a great source of parts and tools that help in the fixing and restoration of video games.

Here is another tip from: -- Big Bear..bob147@bellsouth.net..Thanks..The Real Bob Roberts:

I read this all the time in NG. I admit it's been a hundred years since I was in college, but I think all the same tenets are applicable. I have also seen mfgers make this mistake & I made this mistake myself in mfg & in conversions.

Although I don't think the supply below will do any harm, 4.2a of 12 volt power might be a tad much.

When you start using larger power supplies, i.e., more wattage (the more the better...I don't think so) all else being the same, then only the amperage can be going up, so now you are talking about 22 amps...25 amps....30 amps and etc. in these big power supplies.

An average game pcb is going to draw less than 3 amps. Let me detour for a second.... the first switchers were 4 & 5 amp switchers and when everyone had those, it was said that you needed to upgrade to 7 amps, and when they had those, it was said you needed to upgrade to 10 amps, and then 12 amps & 15 amps & 18 amps. No wonder some of those first pcbs have a bunch of fried components now.

Given that the draw has to stay the same as the resistance is certainly not going to change unless you add something to the pcb, as well as the voltage (5 volts), has to be, then you are only going to draw what that pcb needs for current.

The switching power supplies are designed to operate at a minimum of 15 percent capacity of it's largest ampere output. Supposing you have a 20 amp 5 volt output, you would need to draw a MINIMUM of 3 amps for this supply to operate efficiently. Ok...this looks fine on pcbs that draw 3 amps or above, but is your pcb one that is on the high side, or do you have some of the ones that draw 1 amp, or do you change out pcbs in a single cab where you never know what your draw is?

In practical experience, I've seen ICs sit & bubble the tops up when an internal problem arises when hooked to these power houses. I saw one on a Pole fry the entire last row without ever kicking off. In fact, I truely believe it would have kept right on eating , had I not yanked the plug.

I tried one of the first made for arcade games 200 watt supplies on my work station and noticed right away that if you had a short with a weak link...like a thin pcb trace or internal chip malfunction... this big brute would eat right thru it like a strong man kicking down a paper door, & keep on going as though nothing was ever in it's way.

These supplies have there place. They are great on your PC where you have multiple draw components & they are fine in gaming machines with all there multiple draws ( heavy current draws), although they are not used in our legal gaming machines here, some of the TN mfgers started using them in gray area machines without any problems & some of them require a 3 to 4 amp 12 volt output, as well. This incidently can be bought in the standard type arcade power supply also....just much more expensive.

Factory redesigned PC power supplies specifically for the arcade industry in the 150 watt range with only 15/16 amps output, reducing load requirements to 10 percent or about 1.5 amps, seem to be a good alternative with very little problems, that I have seen anyway, but the standard 5 amp on up power supplies that have around for years seem to do a pretty good job & are readily available & cheap.

Geeeez....Do you really need that jet engine in your VW bug?

Happy Gaming......

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