Please help me troubleshoot my power problem

spmahn

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This is my followup to my thread yesterday as can be seen here http://forums.arcade-museum.com/showthread.php?t=148393

To recap, yesterday I while swapping PCBs on my 4 Player Konami cabinet, the machine decided to stop booting PCB's, and for some reason the coin door stopped lighting up as well. When I switch on the cabinet, I get a marquee light, I get static from the speakers indicating to me that they are on, and I can tell that the monitor is turning on as well.

Following the advice in the thread I posted yesterday, I picked up a multimeter to test my power supply. I have a Happ power supply that has wires in six terminals, +12v, GND, GND, +5v, AC/L, and AC/N. I put the black wire to the AC/N Terminal, and then the red wire to the +12V terminal and +5V Terminal, and both seem to be reading aproximately the correct voltage. Also, the light on the Power Supply is green, indicating that there isn't a problem. I am not an electrical whiz by any means however, in fact I'm just learning this stuff, so maybe I did something wrong.

So if the Power Supply is fine as it seems to be, what should I start checking next? It just seems so bizarre to me that I would lose power only to the Coin Door and possibly the JAMMA Harness, but not anything else.

Any help would be greatly appreciated, and please bare in mind, I'm just learning, so please don't mind my total ignorance. If there's any other information that would be helpful in diagnosing my problem, please let me know. Thanks.

Edit: Upon second look, it appears as though the Coin Slot is powered through the JAMMA Harness, so it appears as though it's the Harness itself that isn't working properly.
 
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When testing a power supply, set your multimeter to Vdc and place your black probe on DC ground (the one closer to the top, usually. the bottom one is for earth ground for AC) and place your red probe on your +5v, +12v in turn respectively.

After doing this, you can confirm that the power supply is outputting the correct dc voltages. The next step is to make that the power is reaching the pcb. This will check the wiring. With the game powered on, and the pcb plugged into the jamma connector, put your black probe on the ground lead and red probe on +5v, then +12v. You will notice that part of the contact on the pcb is still showing when the harness is plugged in, this is a good place to put your multimeter leads. Check all the power positions on the board.
 
here is the jamma standard pinout. Disregard the colors of the wire, they will not match yours. The locations are the same though.

Also is a pic of a pcb with a connector attached and you can see the pins exposed, where you should place your leads when testing for board voltage.
 

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When testing a power supply, set your multimeter to Vdc and place your black probe on DC ground (the one closer to the top, usually. the bottom one is for earth ground for AC) and place your red probe on your +5v, +12v in turn respectively.

After doing this, you can confirm that the power supply is outputting the correct dc voltages. The next step is to make that the power is reaching the pcb. This will check the wiring. With the game powered on, and the pcb plugged into the jamma connector, put your black probe on the ground lead and red probe on +5v, then +12v. You will notice that part of the contact on the pcb is still showing when the harness is plugged in, this is a good place to put your multimeter leads. Check all the power positions on the board.

Ok, the power supply is reading the correct voltage both +12v and +5V, the Jamma Harness however is only reading the +12v, not the +5v.
 
Ok, I fooled around a bit more with my multimeter, and I seem to have isolated the problem. The +5V terminal works fine from the power source, then the wire comes out of the power source, and plugs into this small cylinder shaped fuse looking piece, and is getting power fine on the way into the cylinder shaped piece, but when the wire connects out of the piece, it is dead, no power at all, which means no power going to the Jamma harness.

I apologize for my amateurish description of this, but as I said, I am new to this, and quite frankly I'm shocked at myself that I've even figured out this much. I've included some pictures to illustrate what I see as well, and I do apologize for their poor quality, my digital camera decided to crap out on me tonight, so I had to settle for a flashlight and my iPhone to take these.

So now that I have figured this much out, can anyone give me any further details as to what my problem might be? What is this piece that the wire connects to? Might this piece be my problem?
 

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this small cylinder shaped fuse looking piece

That's a fuse. Shut the power off, pull it out, read it to see what value it is (or take it to a Radio Shack and ask for some new ones), put in a new one, and go from there...
 
I put the black wire to the AC/N Terminal, and then the red wire to the +12V terminal and +5V Terminal, and both seem to be reading aproximately the correct voltage. Also, the light on the Power Supply is green, indicating that there isn't a problem

i hope im wrong but it sounds like you have the A/C from the wall going into the +12

start at the wall and follow the 3 wires into the cabinet and to the small little silver rectangular (line filter). out of that, a wire (black) should go to a fuse and out, then up to the switch on top of the cab and then down to the AC/L input on the PS
the other wire should go to the AC/N input terminal
the green should go to the isolation transformer and all the metal parts in the cab

the +5 should go to the wiring harness as well as the +12 volts
you shouldnt power up a switcher (power supply) without the +5 connected to the game PCB

heres some more info and you should know about this site:
http://therealbobroberts.net/acwiring.html
 
As a late follow up to this, I replaced the the fuses on the cabinet and it fixed all my problems. If only every issue could be fixed for only 2 dollars. Thanks again everybody.
 
the wire comes out of the power source, and plugs into this small cylinder shaped fuse looking piece, and is getting power fine on the way into the cylinder shaped piece, but when the wire connects out of the piece, it is dead, no power at all


That's no fuse! It's a burnt out light bulb.. :)
 
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