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Author Topic: Monitor problem? Need computer guru's help  (Read 2003 times)
mouse
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« on: January 15, 2013, 06:26:08 PM »
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 Huh
THE SYSTEM:
Self assembled PC; cpu Intel core i7; Win7/64
Graphics card: ASUS EAH4670/DI/1GD3/V2
Monitor: HP LP2475w connected to card via HDMI cable.

THE PROBLEM:
System has been running without a single hiccup for 3+ years, until yesterday.
Yesterday I disconnected all inputs and opened the case to install a memory upgrade (6GB to 16GB).
Reconnected all inputs.  On attempting to boot the monitor firmware was unable to detect an active input and showed "CHECK VIDEO CABLE".   Boot failed.   Checked HDMI video cable at both ends and retry, several times.  No joy.

THE SOLUTION??
I had a spare DVI cable handy and connected this between monitor and graphics card.  Monitor recognized the DVI input and computer booted and ran without problem.  New memory recognized and active.

My first assumption was that both the graphics card and monitor were functioning OK.  The problem must be the HDMI cable itself.  Ran out and purchased a new HDMI cable (rather expensive).  Connected new cable to graphics card and monitor.  Same problem recurred.  "CHECK VIDEO CABLE"

THE QUESTION:
Since the connection between graphics card and monitor functions perfectly via DVI, what is causing the failure to connect when using HDMI?  Where should one look for a solution.

Thanks to anyone who can help.
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John McDermott
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« Reply #1 on: January 15, 2013, 07:31:37 PM »
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Try looking for a bent pin.
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mouse
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« Reply #2 on: January 15, 2013, 09:03:08 PM »
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Try looking for a bent pin.

Thanks for the suggestion.  It seems that HDMI connectors do not use pins.
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degrub
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« Reply #3 on: January 15, 2013, 09:30:49 PM »
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http://www.extron.com/download/files/whitepaper/HDMI-cablequality-inProAV.pdf
see if you can look into the connector to verify it is ok on both ends (card and monitor).

Did you force the monitor to the HDMI port ? It sounds like a handshake issue between the card and the monitor.

Frank
« Last Edit: January 15, 2013, 09:34:50 PM by degrub » Logged
aduke
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« Reply #4 on: January 15, 2013, 09:36:27 PM »
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It could be your HDMI cable. Try another to see if this is true.

It could also be a problem with the electronics at either of the HDMI cable. Try to connect the monitor to another computer via your hdmi cable, try to connect another hdmi monitor the existing cable.

Good luck,

Alan
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mouse
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« Reply #5 on: January 16, 2013, 04:45:14 PM »
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My thanks to all who have offered their help.

The following is the rest of the story.  I believe it is a clear proof of a postulate known to all physicists and allied scientists as:  The Law of the Perversity of Inanimate Objects.

I did not begin by re-opening the case to check the seating of the graphics card.  I simply could not believe that this was the problem since the DVI output of that card was functioning normally.  Since a brand new HDMI cable still failed to solve the problem, I reasoned that the fault must lie in the HDMI connector on either the graphics card or the monitor.  To sort this question I obtained a HDMI (male) to DVI (female) connector.  Using this with the known good DVI cable, I tested:

1.  monitor HDMI in to card DVI out.  Worked fine!
2.  monitor DVI in to card HDMI out.  Worked fine!

So apparently the HDMI connectors on both the monitor and card were in good order.

Next I re-tried HDMI to HDMI and, as before, the monitor onscreen display showed failure to detect an active connection and again suggested "CHECK CABLE".  I then made a second attempt; this time I delayed turning the monitor on until the computer finished its boot sequence (as advertised by Microsoft's dulcet tones).  This time the monitor found an active connection (identified as HDMI) and all was well.  Now in the past 3+ years of the use (same computer, same monitor)   such a kludge was never needed, and I find it  hard to believe that simply upgrading my RAM was responsible for this behavior. 

The moral of the story:  Not every malfunction has a legitimate cause; the machinery can simply have a change of heart. 
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degrub
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« Reply #6 on: January 16, 2013, 08:17:43 PM »
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Is the bios running a memory check during boot up ?
It almost sounds like the bios is not turning on the output soon enough and the handshake times out.
If you pull the new memory does it go back to the old behavior ?
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Pete_G
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« Reply #7 on: January 17, 2013, 08:32:32 AM »
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Is the bios running a memory check during boot up ?
It almost sounds like the bios is not turning on the output soon enough and the handshake times out.
If you pull the new memory does it go back to the old behavior ?

This sounds like a possible cause. If your BIOS supports it try enabling Quick power On Self-Test or whatever your BIOS calls it.
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mouse
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« Reply #8 on: January 18, 2013, 02:57:56 PM »
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Thanks for the replies.
The BIOS is running a memory test during post.
It may have caused a timeout of the monitor's auto-scan function.

I have found a simple solution to the problem.  Using the monitor's on-screen menu I have disabled the "auto-scan for input" and set HDMI as the default input.  Now working perfectly.

Again many thanks to all who offered their help.
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