HEEELP, arcade monitor noise when plugging a PC
I hope somebody can tell me what can be happening. I am trying to connect a new PC (not so new, 2008) that I have prepared, to my MAME cabinet. Problem is that it seems to be passing some electricity through the VGA cable to the monitor, and now it's noisy. Noise is present even if I don't turn on the PC, it starts when I plug it in. This doesn't happen with the old PC that the cabinet came with.
Comments
Any chance the new PC needs to be grounded?
How should I do that? I'm a total noob, I know. Oh, another clue is that the new PC sometimes turns off seconds after turning on, I have to unplug, plug and try again (sometimes it happens several times after I can finally turn it on).
I think I'd start with trying a new cable - finding one with a ferritte core choke might help, but just trying other cables would be interesting. You can also add a ferritte choke to an existing cable which is supposed to dampen any interference.
The next thing I think I'd try here would be to see if the buzz is there when the computer is unplugged. If so, leave it unplugged and push the power button a few times to see if you can drain the capacitors in the power supply. If the buzz goes away after a few button presses then I think I'd try replacing the power supply. It seems like you might have power problems anyway since you noted that the PC sometimes just turns off.
Be thankful you have a buzz because at least it is an obvious signal you can troubleshoot. Random shut downs are really hard to troubleshoot by themselves.
So, the chassis is passing some electricity to the motherboard, and also, some electricity is passing from the mobo to the vga connector in the absence of the cabinet.
Any chance the new PC needs to be grounded?
How should I do that? I'm a total noob, I know. Oh, another clue is that the new PC sometimes turns off seconds after turning on, I have to unplug, plug and try again (sometimes it happens several times after I can finally turn it on).
Just chiming in to possibly comment on the PC turning off seconds after turning on...few things this could be if a traditional PC:
1 - the motherboard is attached to the case with little metal studs - if possible check that all your motherboard support holes are secured and tight. If you can remove the back of the case to see the underside of the motherboard, try to see if any "extra" studs are inserted in the case. If you can't it might be worth your time to unscrew the motherboard and to check the case for any extra studs. These can cause a variety of issues.
2 - the tower front panel (power button, usb ports, audio etc) has a series of wires that go to the motherboard. If any of these are frayed or loose or ungrounded it can cause the above symptom. On a fresh build recently, my USB cord would cause exactly where you're describing when the power was pressed. Disconnected the USB and boom it works perfect.
Good luck!
Any chance the new PC needs to be grounded?
How should I do that? I'm a total noob, I know. Oh, another clue is that the new PC sometimes turns off seconds after turning on, I have to unplug, plug and try again (sometimes it happens several times after I can finally turn it on).
Just chiming in to possibly comment on the PC turning off seconds after turning on...few things this could be if a traditional PC:
1 - the motherboard is attached to the case with little metal studs - if possible check that all your motherboard support holes are secured and tight. If you can remove the back of the case to see the underside of the motherboard, try to see if any "extra" studs are inserted in the case. If you can't it might be worth your time to unscrew the motherboard and to check the case for any extra studs. These can cause a variety of issues.
2 - the tower front panel (power button, usb ports, audio etc) has a series of wires that go to the motherboard. If any of these are frayed or loose or ungrounded it can cause the above symptom. On a fresh build recently, my USB cord would cause exactly where you're describing when the power was pressed. Disconnected the USB and boom it works perfect.
Good luck!
Believe me, your input is really appreciated. The motherboard is attached to the case with screws that go in holes, in several protuberances that raise it a bit. I believe these are the studs right? So I have to check if there are any studs that have no screws, and if so, put a screw in them?
I'll check those cables you mention, but how should I ground them? Is there any "grounding for dummies" guide I can check?
I have done some troubleshooting (haven't tried a different power cable, I'll try that). The noise is there only when I plug the PC (and the only cable connected to the cabinet is the VGA cable). I tried disconnecting the PC motherboard from the PC power supply: there is noise. I tried taking out the motherboard and the power supply (connected to each other) from the pc chassis and it still shows noise. Obviously, if I disconnect the power supply from the motherboard, outside the pc chassis, it doesn't show noise.
So, the chassis is passing some electricity to the motherboard, and also, some electricity is passing from the mobo to the vga connector in the absence of the cabinet.
I meant try a different VGA cable, but the power cable is a good idea too.
If I'm reading this correctly the MoBo and the Powersupply outside of the PC Chassis (sitting on your desk or something) produce the noise? If so, you've got to try a different power supply next. If for no other reason than you should eliminate it as the cause.
Regarding grounding, it isn't like any of the components you are dealing with would NOT be grounded. The Molex connectors that connect PC components all have ground wires that connect to common ground points on the MoBo or elsewhere. What you are looking for could be something that has come a little loose and the ground is no longer connected. Grounding it would be a matter of just plugging it back in for most cases, but it also could require replacing an electrical component. The power supply is a bit more closed than most of the components. If something has come loose in there it could be causing this problem. You could open it and inspect it for a blown capacitor or some other damage, but you are better off trying a different one to see if your problem just goes away.
I have done some troubleshooting (haven't tried a different power cable, I'll try that). The noise is there only when I plug the PC (and the only cable connected to the cabinet is the VGA cable). I tried disconnecting the PC motherboard from the PC power supply: there is noise. I tried taking out the motherboard and the power supply (connected to each other) from the pc chassis and it still shows noise. Obviously, if I disconnect the power supply from the motherboard, outside the pc chassis, it doesn't show noise.
So, the chassis is passing some electricity to the motherboard, and also, some electricity is passing from the mobo to the vga connector in the absence of the cabinet.
I meant try a different VGA cable, but the power cable is a good idea too.
If I'm reading this correctly the MoBo and the Powersupply outside of the PC Chassis (sitting on your desk or something) produce the noise? If so, you've got to try a different power supply next. If for no other reason than you should eliminate it as the cause.
Regarding grounding, it isn't like any of the components you are dealing with would NOT be grounded. The Molex connectors that connect PC components all have ground wires that connect to common ground points on the MoBo or elsewhere. What you are looking for could be something that has come a little loose and the ground is no longer connected. Grounding it would be a matter of just plugging it back in for most cases, but it also could require replacing an electrical component. The power supply is a bit more closed than most of the components. If something has come loose in there it could be causing this problem. You could open it and inspect it for a blown capacitor or some other damage, but you are better off trying a different one to see if your problem just goes away.
Thank you for the help, I'll try that.
Any chance the new PC needs to be grounded?
How should I do that? I'm a total noob, I know. Oh, another clue is that the new PC sometimes turns off seconds after turning on, I have to unplug, plug and try again (sometimes it happens several times after I can finally turn it on).
Just chiming in to possibly comment on the PC turning off seconds after turning on...few things this could be if a traditional PC:
1 - the motherboard is attached to the case with little metal studs - if possible check that all your motherboard support holes are secured and tight. If you can remove the back of the case to see the underside of the motherboard, try to see if any "extra" studs are inserted in the case. If you can't it might be worth your time to unscrew the motherboard and to check the case for any extra studs. These can cause a variety of issues.
2 - the tower front panel (power button, usb ports, audio etc) has a series of wires that go to the motherboard. If any of these are frayed or loose or ungrounded it can cause the above symptom. On a fresh build recently, my USB cord would cause exactly where you're describing when the power was pressed. Disconnected the USB and boom it works perfect.
Good luck!
Believe me, your input is really appreciated. The motherboard is attached to the case with screws that go in holes, in several protuberances that raise it a bit. I believe these are the studs right? So I have to check if there are any studs that have no screws, and if so, put a screw in them?
I'll check those cables you mention, but how should I ground them? Is there any "grounding for dummies" guide I can check?
Yep, you're on the right track, the motherboard likely has 6-9 mounting points. Underneath the mounting points will be little gold studs that screw into your case and then on the top of the mobo, the screws would securely hold the mobo to the studs. If any of the mounting points are not safely secured OR there are extra studs on the PC case underneath the mobo, the motherboard can short out almost instantly.
For the wires coming from the tower, you might want to lookup the specific motherboard online and find the owner's manual (unless you have the manual). There is a diagram of where everything plugs into, and the wires themselves should be labeled. First just check that they are all securely connected to the pins on the motherboard, if any are not tight, it could cause the issues. Would be good to double check that they are on the right pins too. Then, you might want to only plug in the power button wire and unplug the rest. See what happens, you might get lucky!
This really sounds like what was happening with my last PC build - it drove me bonkers. I double checked the motherboard studs/screws many times, even took the motherboard out and ran it on my coffee table outside of the case, which is a "bench test". I would press the power button, it would power on and light up and then after 1-2 seconds would shut off cold. Finally figured out my USB wire must have been frayed or something and when I unplugged it, I haven't had a problem since. If I want my front USBs, I'll probably have to get a replacement wire or try to repair the cord if I can.