Why would someone use 2 power supplies

FastZEdy

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I have an NBA jam that plays blind. When I opened up the cabinet it was a rats nest of wires and spliced connections of which the power wires to be monitor chassis fell out of the power molex, touched and blew the original power supplies fuse..in other words it's a mess.

I am going to redo all the power distribution BUT my question is why would someone use 2 power supplies?

In this case a new switching one goes to the pcb and then it's spliced into the original one which is a psu+iso that powers the monitor, speakers/amp, marquee light, coin door. In other words it's like a psu going to a psu..I thought maybe the original psu didn't work but it's where all the power comes in as the fuse blew and the cabinet is completely dead.

Or maybe it was just being used as a distribution block.

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They also have literally a dozen ground wires all terminated to the old psu block..and then a small ribbon cable which I assume is some sort of ground for the cabinet attached from a screw up front and going no where laying in the cabinet
 
Where is the second power supply?

In the picture and video you posted I can see a transformer on a Power Block and an SMPS Power Supply.

The SMPS Power Supply powers the Game board. The Transformer allows input voltage range selection and provides isolated mains (AC) for the Monitor and a low voltage AC for the Coin Door Lamps.

NBA Jam uses both of these parts. The ground wiring is a good (star) earth grounding point on the Power Block.

If you look at the Power Supply wiring in the manual it shows the correct wiring.

If a lot of the wires are hanging loose, they probably just need routing back to cabinet correctly.

Not sure what the Ribbon cable is for, it is not ground. Where does it go?
 
Sorry I assume this is a psu where the iso is sitting on as it's a separate fuse, maybe it's just a distribution block
 

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there's 2 fuses on the power assembly. one is for the line in power from the wall primary side and the other is for the secondary side of the transformer. you could easily discern this information from the labels on the power assembly or you can read the game manual.

do you know what the isolation transformer does? it takes the wall power in and distributes it out the secondary side to power the monitor, power supply, and marquee light. if you're intent on just playing your games you don't need to know this, but you keep creating threads and you should probably gather a fundamental understanding of what you're doing if you're intent on servicing arcade games.

your power supply is ancient and needs to be replaced. your monitor apparently doesn't work. if you haven't done anything to the monitor yet you either should learn how to fix it or learn how to disassemble it to pack in a box properly to send to someone else who can do it for you. the monitor model would be valuable information to the rest of us if you want further guidance on the matter.

take a picture of the circuit board components of the monitor, the tube manufacturer and possible Wells-Gardner labels or whatever else are irrelevant.
 
I've used 2 different 15Amp power supplies combined on a test bench, when I needed a more accurate and higher capacity -5V bus.
I connected the the +5V (power supply) to PCB Ground on the second power supply, and the Ground to -5V on the PCB (Essentially using the +5V capacity for -5V power). It also allowed me to have an adjustable voltage for -5V.
 
Yes thx! It's WG 7xxx. Helpful
Appreciate the write up
ok so K7000 you need to remove the chassis and do some inspection. if the fuse is blown in most instances the HOT is shorted, but with diode check on your meter also test C36 (if 4 leg cap you test the legs kitty corner from each other; if it's 2 separate caps you'll test C36 and C69) and C38 (which is probably the next most common shorted part). if the fuse isn't blown test the stand up R103 ceramic resistor by the filter cap, it's rated at 2.7 ohm but may test closer to 3.4 ohm. if it's an ohm or more higher than that the part's on its way out. check C57, if the outer layer is peeling down or the cap is domed, that's the B+ filter cap and it being bad will kill the monitor until you replace it. R101's skinny trace side connected to C23 is prone to burning out the solder pad, if this isn't connected the monitor won't work either. I might get around to doing a K7000 video demonstration this week, you can see how I do it if my job needs permit it.
 
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