# Fixing old PC, no video signal



## Solidify (May 12, 2011)

I'm trying to get an old computer working again. I was wondering if someone wouldn't mind walking me through the process.

This is the computer: HP Pavilion Media Center TV m7640n Desktop PC | HP® Support

The computer boots up but does not give a video feed. 

I tried:

resetting the CMOS battery
taking out the RAM modules
I also tried putting a video card that I know works for a fact and connecting to VGA cable through the video card but that didn't work also. 

What else can I try?

I have a small 4-pin motherboard speaker but I don't know why it doesn't make at POST beeps when I connect it.


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## sobeit (Nov 11, 2007)

if it doesn't matter if you are using a video card or not, check the back of the computer, there might be a black cover over an onboard video port, take off the cover, pull the video card, plug the vga cable there.


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## Solidify (May 12, 2011)

sorry I dont understand what you'd like me to try..


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## Solidify (May 12, 2011)

This is the board:









A8M2N-LA


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## sobeit (Nov 11, 2007)

I did not say motherboard. I said on the back of the computer. To be specific computer case.

1. See if there is a small black cover over a port
2. if so, take the black cover off
3. there should be an onboard video vga port there
4. plug in your monitor cable and see if your monitor works/


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## Solidify (May 12, 2011)

OK, I'm looking at the back of the computer case.


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## Solidify (May 12, 2011)

I don't mean to be a pain but I still don't understand what I need to do. My board only has one VGA port, even without the I/O plate, that's all I see. 

Maybe this will help?


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## sobeit (Nov 11, 2007)

as I said, there might be a black cover. since there ain't one, then my suggestion does not apply.

I had a very similar computer, very same case/motherboard, when my video card when out, I was able to use the onboard video by doing what I posted. Since you did not mention you were already using onboard video, my suggested true and tried suggestion does not apply.


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## Solidify (May 12, 2011)

> you did not mention you were already using onboard video


Sorry about that. 

Anything else I can do to find out the problem?


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## Solidify (May 12, 2011)

I think it might be the onboard video that crapped out but I dont understand why when I try putting a working on-add video card, that too still does not give me any feed...


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## Solidify (May 12, 2011)

I just tried with a different PSU but no luck.


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## Tyree (May 10, 2009)

When installing a dedicated GPU the Mobo "should" default to it but sometimes you need to boot to the Bios and select the GPU as the primary video source.


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## Solidify (May 12, 2011)

How can I boot to the BIOS if I don't get a video signal/feed? I tried with DVI, VGA, HDMI.. nothing.


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## Tyree (May 10, 2009)

Have you removed the GPU and connected the monitor to the Onboard connection?


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## Solidify (May 12, 2011)

Well the onboard video is what didn't work to begin with. SO i tried to use a dedicated(add-on) video card but that didnt work either


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## Rich-M (May 2, 2007)

Reset the bios by pulling the small watch battery on the motherboard and holding out for 2-5 minutes before resetting it back. Then see if you can boot to see the bios either way with the other video card in use or the onboard video.


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## Solidify (May 12, 2011)

Rich-M said:


> Reset the bios by pulling the small watch battery on the motherboard and holding out for 2-5 minutes before resetting it back. Then see if you can boot to see the bios either way with the other video card in use or the onboard video.





> I tried:
> 
> *resetting the CMOS battery*
> taking out the RAM modules
> I also tried putting a video card that I know works for a fact and connecting to VGA cable through the video card but that didn't work also.


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## Rich-M (May 2, 2007)

Look very closely at the board and see if you can see the cmos jumper...if you can move it from the pins it is on to the left or right, whichever you can do and then try to start pc again. When it does not start then try the video card again.
Out of curiosity when you try to start the system without the ram installed at all, do you hear any beeps from the system board?


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## Solidify (May 12, 2011)

No, no beeps at all, with or without the RAM modules installed.

I'll try that in a second.


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## The_Janitor (Sep 10, 2012)

No BIOS beeps means the problem is happening before the video even comes into play. Are all the fans spinning? Are you sure you are plugging in BOTH power cables?


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## Rich-M (May 2, 2007)

Oh well that means there is no speaker then. I am beginning to think this is a motherboard.


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## Solidify (May 12, 2011)

Which pin do I need to move?


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## Tyree (May 10, 2009)




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## Solidify (May 12, 2011)

Hm, if the cmos jumper in your image is correct, mine was was wrong this whole time, unless it varies according to motherboard type... I'll try the way you posted it, but if that doesn't work, anything else I can try? Just trying to minimize the time I have to spend waiting for you to suggest me things..


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## The_Janitor (Sep 10, 2012)

Solidify said:


> Hm, if the cmos jumper in your image is correct, mine was was wrong this whole time, unless it varies according to motherboard type... I'll try the way you posted it, but if that doesn't work, anything else I can try? Just trying to minimize the time I have to spend waiting for you to suggest me things..


The motherboard should have printing to explain the CMOS jumper, such as 1-2 normal, 2-3 clear.

What about having BOTH power cables plugged in to the motherboard.


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## Tyree (May 10, 2009)

CMOS jumper configuration is commonly on the 1 & 2 pin for normal operation. The pin is move from 1 & 2 to 2 & 3 for a few seconds to clear the CMOS and then moved back to 1 & 2.


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## Solidify (May 12, 2011)

Janitor, which two power cables are you talking about? 

Tyree, I tried every CMOS jumper configuration as well as the one specified in the board's manual, no luck.


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## Solidify (May 12, 2011)

What I have a hard time understanding is that even if I give myself the benefit of the doubt and assume that the onboard video no longer works, I still can't understand why I also have no feed when using the video card (for which I'm certain works since that's the one I'm using right now).


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## shawnpb (May 30, 2010)

Rich-M said:


> Oh well that means there is no speaker then. I am beginning to think this is a motherboard.



As mentioned here. The motherboard may be bad. Take the quarter size which is next to your hand in one of your imaged posts. Take the battery out wait 10 minutes. Put the battery in try starting up the pc and try to get into bios.


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## Solidify (May 12, 2011)

I tried that, I think I mentioned it in my first post. It didn't work.


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## Tyree (May 10, 2009)

The issue is looking more and more like a bad Mobo. OEM components are low quality and not made or intended to last so it's not a big shocker.


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## Solidify (May 12, 2011)

Is there a definitive way to confirm the board is done or would you say that's as clear as it'll get?


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## Rich-M (May 2, 2007)

Usually its process of elimination, especially if there is no speaker on the motherboard.


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## Solidify (May 12, 2011)

Well there is a speaker on the motherboard, it says "BUZZ" beside it, atleast I think that's a speaker.. not working though obviously. Look at the image in Post #4, you can see the black circle, the speaker right above the 20+4 pin motherboard power port.


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## Tyree (May 10, 2009)

Solidify said:


> Well there is a speaker on the motherboard, it says "BUZZ" beside it, atleast I think that's a speaker.. not working though obviously.


Or the Mobo is bad.......... so no beeps.


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## The_Janitor (Sep 10, 2012)

Solidify said:


> Janitor, which two power cables are you talking about?
> 
> Tyree, I tried every CMOS jumper configuration as well as the one specified in the board's manual, no luck.


There is the primary power cable (20/24 pins) and the "auxillary" power cable, what I call the "4-pack". I'm sure there are technically correct terms for these. They both must be fastened to the motherboard.


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## Solidify (May 12, 2011)

Yes, they both are.


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