Composite video port


12 posts
by recantha2 » Tue Nov 20, 2012 9:31 am
Hi.
I have two Pis: a Rev 1 and a Rev 2. Both 256mb versions.
The Rev 2 board does not output on it's composite video port (or at least nothing displays when plugging a screen in).
The Rev 1 board, with the same cable and same screen, does work.
Obviously, I'd want both boards working, so I did a little investigation. I measured the voltage across the composite port using the solder points for the port on the underside of the Pi.
The Rev 1 measured about 2.5v
The Rev 2 measured about 0.6v

Is this indicative of a problem, or is this just a difference between the two Revisions?
If it is a possible problem, what could I do to fix it? Any ideas?

Hope someone can help,
--
Mike
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by jamesh » Tue Nov 20, 2012 9:46 am
There shouldn't be any difference on the composite ports if they are both doing the same thing at time of measurement. Might be indicative of a fault. Any obvious signs of bad solder joints?

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by recantha2 » Tue Nov 20, 2012 9:56 am
The only thing I can see visually different is a slight discolouration on the solder of the pin nearest the edge of the board. I guess I'd call it yellowish/brownish? It's hardly more than a slight shadow, though.
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by redhawk » Tue Nov 20, 2012 10:05 am
Is your PI rev2 board working have you tested the video via HDMI, does your OK/ACT led blink etc??

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by recantha2 » Tue Nov 20, 2012 10:08 am
Oh, the Rev 2 works absolutely fine for everything else. The HDMI works for output, LEDs flashing away and it runs my latest project beautifully. It's just the composite port.
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by redhawk » Tue Nov 20, 2012 10:36 am
Sounds like you have a faulty board however just to make sure try starting the PI rev2 without the HDMI cable and then connect this to the TV.

Does your PI still show HDMI video??

The PI normally disables the composite port if a HDMI device is detect it's possible your PI is misreading this status.

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by recantha2 » Tue Nov 20, 2012 5:22 pm
If I start the Pi with the HDMI connected, once it's started I can plug and unplug to be heart's content and it still shows a picture.
If I start it without the HDMI and _then_ plug it in, I don't get a picture (which I _believe_ is the expected behaviour).
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by redhawk » Tue Nov 20, 2012 5:50 pm
In that case your PI rev2 board is more cetainly defected.

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by recantha2 » Tue Nov 20, 2012 6:00 pm
Oh... Jolly good. Nuts. Wonder if there's anything I can do about that myself?
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by redhawk » Tue Nov 20, 2012 9:55 pm
I guess that depends on how much you need the composite video output since you already have HDMI capable equipment.

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by recantha2 » Tue Nov 20, 2012 9:56 pm
I really could do with the composite. I have a 5" screen with composite, so it's portable.
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by redhawk » Tue Nov 20, 2012 9:59 pm
I guess you don't have much choice but to send it back. :?
If it's RS then use the info from this page: http://authenticate.rsdelivers.com/stat ... turns.aspx

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