HDMI Output Keeps Blacking out


9 posts
by AgentJR007 » Mon Jan 21, 2013 5:10 pm
My Raspberry Pi HDMI output keeps blacking out when I set the pi to do a demanding task such as the pre-installed python games on rasbian wheezy.

I am using a HDMI to VGA adaptor. Is that the problem?

Any Help would be appreciated.
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by drgeoff » Mon Jan 21, 2013 10:41 pm
1. Is it just the HDMI output that goes or the whole RPi?

2. Are you sure your power supply is OK? More demanding tasks can draw more current. PSU troubleshooting hints at http://elinux.org/R-Pi_Troubleshooting# ... r_problems.

3. All HDMI to VGA converters are not created equal. What one are you using?
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by johnbeetem » Mon Jan 21, 2013 11:58 pm
Definitely sounds like a power problem. I had similar behaviour when I was using an iffy power supply with RasPi. For example, when I started up gcc the screen would get little green dots and sometimes blank out, but would come back when the compile was done.

You may be able to fix the problem following the Troubleshooting Power Supplies advice drgeoff links to. The usual culprits are iffy Micro USB cables and sometimes polyfuse F3. However, if you're powering your HDMI to VGA converter from RasPi it could be that you're getting too much drop across a working polyfuse F3 when you add the current demands of RasPi plus the converter.

You might check out the RasPi Hardware Wiki for some HDMI to VGA converter lore: http://elinux.org/RPi_VerifiedPeriphera ... rter_boxes

Some people have hacked their HDMI to VGA converters to use external power so that it doesn't go through RasPi.

If you have a model 2.0 RasPi (or 1.0 with 0 Ohm jumpers in place of polyfuses F1 and F2) you might try back-powering RasPi from a powered hub instead of using the Micro USB plug. This avoids the voltage drop across F3, though it does lose the protection offered by F3.
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by AgentJR007 » Tue Jan 22, 2013 7:06 pm
I am using this:
http://www.amazon.com/Cable-Matters-Plated-Premium-Adapter/dp/B007Z0UBFW/ref=sr_1_5?ie=UTF8&qid=1358881516&sr=8-5&keywords=cable+matters+vga+to+hdmi

adaptor

The power supply came with a set from maplins so it should be fine however I will check.
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by AgentJR007 » Tue Jan 22, 2013 7:14 pm
Thanks sooooooo much. It was the power cable. Seems to work fine now when using a phone charger.
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by drgeoff » Tue Jan 22, 2013 7:17 pm
That adaptor does not have its own power supply. The RPi's HDMI output does not supply enough power for most of these adaptors. That is likely to be the cause of your problem.

http://elinux.org/RPi_VerifiedPeriphera ... rter_boxes

and

"Micro HDMI-VGA conversion may post compatibility issues under the following conditions
.......
The Micro HDMI output of source device does not supply 5V/500mA power "

from the Amazon page linked above.

There may even be a risk of damage to the RPi. viewtopic.php?f=28&t=9819.
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by AgentJR007 » Tue Jan 22, 2013 7:29 pm
Correction. I meant this one. [url]Cable Matters Gold Plated Premium HDMI to VGA Active M/F Adapter in White[/url]

is there any code that can emergency shutdown in case of an overload?
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by drgeoff » Tue Jan 22, 2013 8:09 pm
AgentJR007 wrote:Correction. I meant this one. [url]Cable Matters Gold Plated Premium HDMI to VGA Active M/F Adapter in White[/url]

is there any code that can emergency shutdown in case of an overload?


You haven't included a proper URL.

AFAIK the RPi does not have any hardware which can be configured to sense an overload. Without that, any code would be pointless.
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by AgentJR007 » Tue Jan 22, 2013 8:14 pm
thank you
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